Biomedical subjects

Cesario Bianchi

Publications and source records attributed to Cesario Bianchi.

At least 19 recordsLinked to original sources

PubMed2006

High-dose atorvastatin improves hypercholesterolemic coronary endothelial dysfunction without improving the angiogenic response.

BACKGROUND: Although 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) can restore endothelial function in coronary disease, in vitro and murine studies have shown their effects on myocardial angiogenesis to be biphasic and dose dependent. We investigated the functional and molecular effects of high-dose atorvastatin on the endogenous angiogenic response to chronic myocardial ischemia in hypercholesterolemic swine. METHODS AND RESULTS: Yucatan pigs were fed either a normal (NORM group; n=7) or high-cholesterol diet, with (CHOL-ATR group; n=7) or without (CHOL group; n=6) atorvastatin (3 mg/kg per day) for 13 weeks. Chronic ischemia was induced by ameroid constrictor placement around the circumflex artery. Seven weeks later, microvessel relaxation responses, myocardial perfusion, and myocardial protein expression were assessed. The CHOL group demonstrated impaired microvessel relaxation to adenosine diphosphate (29+/-3% versus 61+/-6%, CHOL versus NORM; P<0.05), which was normalized in the CHOL-ATR group (67+/-2%; P=NS versus NORM). Collateral-dependent myocardial perfusion, adjusted for baseline, was significantly reduced in the CHOL group (-0.27+/-0.07 mL/min per gram versus NORM; P<0.001) as well as the CHOL-ATR group (-0.35+/-0.07 mL/min per gram versus NORM; P<0.001). Atorvastatin treatment was associated with increased phosphorylation of Akt (5.7-fold increase versus NORM; P=0.001), decreased vascular endothelial growth factor expression (-68+/-8%; P<0.001 versus NORM), and increased expression of the antiangiogenic protein endostatin (210+/-48%; P=0.004 versus NORM). CONCLUSIONS: Atorvastatin improves hypercholesterolemia-induced endothelial dysfunction without appreciable changes in collateral-dependent perfusion. Increased myocardial expression of endostatin, decreased expression of vascular endothelial growth factor, and chronic Akt activation associated with atorvastatin treatment may account for the diminished angiogenic response.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

PubMed2006

Indices of apoptosis activation after blood cardioplegia and cardiopulmonary bypass.

BACKGROUND: Cardioplegic arrest (CA) using cold blood cardioplegia (CBC) has been reported to reduce ischemia-reperfusion (IR)-induced myocardial injury via apoptosis. We studied key apoptotic mediators via the caspase-dependent and intrinsic pathways as well as poly(ADP)-ribosylating protein (PARP) activity in myocardial and peripheral tissues after CA and cardiopulmonary bypass (CBP). METHODS AND RESULTS: Right atrial (RA) and skeletal muscle(SM) was harvested from cardiac surgical patients with similar baseline characteristics (N =6) before and after CPB and CBC. Total and modified caspase-3, Bcl-2, Bad, apoptosis-inducing factor (AIF), and PARP were quantified by immunoblotting. Terminal caspase-3 activity was assessed and immunohistochemistry was performed for PARP and AIF. TUNEL staining was used for identification of apoptotic cells. Microarray gene expression analysis was performed using Affymetrix U95 GeneChip. In RA tissue, CA with CBC significantly increased phosphorylation of Bcl-2 (Ser70), Bad (Ser112) (2.63+/-0.4 and 1.77+/-0.3-fold respectively; P<0.05), and cleavage of the downstream caspase 3 (1.45+/-0.1-fold; P<0.05). There was no significant change in total protein levels. Also, there was an increase in mature AIF (57 kDa) levels (1.22+/-0.01-fold; P<0.05) and a trend toward nuclear translocation on histological staining. Caspase 3 activity was increased 1.5+/-0.14-fold (P<0.05). The number of apoptotic cells in atrial tissue increased after compared with before CPB/CA using TUNEL staining (1.55+/-0.66 versus 0.325+/-0.05%, respectively; P=0.03). In contrast, SM samples did not show any of the changes observed in RA tissue after CPB. CONCLUSIONS: Despite optimal current surgical myocardial protection, we found that CA with CBC induced both programmed cell death and survival signaling in myocardial tissue.

Aged↗

PubMed2006

Role of stromal-derived factor-1alpha in the induction of circulating CD34+CXCR4+ progenitor cells after cardiac surgery.

BACKGROUND: Cardioplegia and cardiopulmonary bypass (CP/CPB) leads to an increase in circulating progenitor cells. The role of stromal-derived factor-1alpha (SDF-1alpha), a key regulator of progenitor cell mobilization, and other cytokines in this process is not clear. METHODS AND RESULTS: Peripheral blood (n=24), atrial and skeletal tissue (n=6) samples were taken from patients undergoing CP/CPB before (pre-CP/CPB), 4 hours (post-CP/CPB), and 4 days (POD4) after CP/CPB. The number of circulating CD34+CXCR4+ cells increased post-CP/CPB (442+/-53 versus 286+/-27; P=0.04 versus pre-CP/CPB), but not at POD4 (382+/-50; P=0.28 versus pre-CP/CPB). Plasma levels of SDF-1alpha increased post-CP/CPB as compared with pre-CP/CPB (3325+/-325 versus 2911+/-165 pg/mL; P=0.046) but returned to baseline at POD4 (2838+/-224 pg/mL; P=0.90). Plasma levels of vascular endothelial growth factor were similar post-CP/CPB (P=0.90 versus pre-CP/CPB) but increased at POD4 (220+/-40 pg/mL versus 134+/-26 pg/mL; P=0.04 versus pre-CP/CPB). Serum levels of granulocyte-colony stimulating factor (G-CSF) increased early after CP/CPB as compared with pre-CP/CPB (265.0+/-41.7 versus 11.1+/-1.1 pg/mL; P<0.001) and returned to baseline at POD4 (P=0.84 versus pre-CP/CPB). The circulating CD34+CXCR4+ cells were positively correlated with plasma levels of SDF-1alpha early after CP/CPB (r=0.56, P<0.01), but not at other times. Protein expression of SDF-1alpha was elevated in the atrial myocardium after CP/CPB (9.4-fold; P=0.03). CONCLUSIONS: Exposure to CP/CPB leads to an increase in circulating CD34+CXCR4+ progenitor cells, which is associated with increased myocardial SDF-1alpha expression. The numbers of CD34+CXCR4+ progenitor cells positively correlate with the plasma levels of SDF-1alpha post-CP/CPB, suggesting an important role of SDF-1alpha in progenitor cell mobilization.

Aged↗

PubMed2006

Hypercholesterolemia impairs the myocardial angiogenic response in a swine model of chronic ischemia: role of endostatin and oxidative stress.

BACKGROUND: Recent studies have shown that angiogenesis is regulated by a balance between activators and inhibitors. We investigated the effects of hypercholesterolemia on the functional angiogenic response and collateral formation induced by chronic myocardial ischemia and the expression of angiogenic mediators. METHODS: Twelve Yucatan miniswine, fed either a normal (NORM, n = 6) or high cholesterol (HCHO, n = 6) diet for 13 weeks, underwent ameroid constrictor placement around the circumflex artery. Three weeks later, myocardial perfusion was quantified using isotope-labeled microspheres. Seven weeks after ameroid placement, coronary microvascular responses and myocardial perfusion were assessed. Vascular density was evaluated by PECAM-1 (CD-31) staining, and vascular endothelial growth factor, endothelial nitric oxide synthase, endostatin, and angiostatin protein levels were determined. Myocardial protein oxidation was quantified. RESULTS: Coronary microvessels from HCHO pigs showed significant endothelial dysfunction. Baseline-adjusted myocardial flow at 7 weeks was significantly reduced in the HCHO animals (-0.002 +/- 0.06 versus +0.23 +/- 0.09 mL/min/g, HCHO versus NORM, p = 0.04). Endostatin expression was significantly increased in the HCHO pigs (2.2-fold, p = 0.001 versus NORM). There was a mild reduction in myocardial vascular endothelial growth factor expression (-29% +/- 14%, p = 0.09) in HCHO animals, but no difference in expression of endothelial nitric oxide synthase and angiostatin. The HCHO animals demonstrated increased myocardial protein oxidation compared with the NORM group (+155% +/- 21%, p = 0.03 versus NORM). CONCLUSIONS: Ischemia-induced angiogenesis is inhibited in hypercholesterolemic pigs with a concomitant increase in endostatin expression and oxidative stress. These findings suggest that under conditions of hypercholesterolemia, coronary collateral development may be regulated by endogenous angiogenesis inhibitors such as endostatin as well as reactive oxygen species.

Animals↗

PubMed2006

Human coronary microvascular effects of cardioplegia-induced stromal-derived factor-1alpha.

BACKGROUND: Stromal-derived factor-1alpha (SDF-1alpha) binds to its specific receptor, CXCR4, and plays an important role in ischemia-induced angiogenesis. Some of the effects of SDF-1alpha are likely due to effects on the microcirculation. Cardioplegia and cardiopulmonary bypass (CP/CPB) activate mitogen-activated protein kinase (MAPK) signaling pathways including p38, ERK1/2, and JNK. The purpose of the present study was to evaluate SDF-1alpha expression, and relationships between SDF-1alpha-mediated coronary microvessel response and MAPKs. METHODS: The atrial tissue of patients undergoing cardiac surgery was harvested before and after CP/CPB. Protein levels of SDF-1alpha and CXCR4 were measured by Western blot and immunohistochemistry, and plasma levels of SDF-1alpha were measured by enzyme-linked immunosorbent assay. Coronary microvessel responses to SDF-1alpha were assessed by videomicroscopy. To further elucidate SDF-1alpha/CXCR4 signaling, microvessel responses were evaluated in the presence of CXCR4 antagonist (AMD3100) and MAPK inhibitors, ERK1/2 inhibitor (UO126), p38 inhibitor (SB203580), and JNK inhibitor (ALX-159-600). RESULTS: Myocardial protein expression of SDF-1alpha was elevated after CP/CPB (9.5 +/- 3.5-fold, p = 0.03 versus before CP/CPB). Increases in SDF-1alpha spatially localized to endothelial cells, smooth muscle cells, and myocytes. Plasma levels of SDF-1alpha were increased after CP/CPB (3.2 +/- 2.8 versus 2.8 +/- 1.7 ng /mL, p = 0.03 versus before CP/CPB). Stromal-derived factor-1alpha induced coronary microvessel contraction after CP/CPB (p = 0.046 versus before CP/CPB), which was blocked by the CXCR4 antagonist. Furthermore, SDF-1alpha induced microvessel contraction was inhibited by MAPK inhibitors, ERK-1/2 (p = 0.046), p38 (p = 0.049), and JNK inhibition (p = 0.06). CONCLUSIONS: These results suggest that CP/CPB induces myocardial expression of SDF-1alpha and results in coronary microvessel contraction through MAPK signaling pathways.

Aged↗

PubMed2006

C-Reactive protein and inflammatory response associated to neurocognitive decline following cardiac surgery.

BACKGROUND: It has been recognized that neurocognitive decline (NCD) often occurs as a complication in cardiac surgery. The early inflammatory response and C-reactive protein (CRP) was examined in relation to NCD and to a marker of axonal central nervous system (CNS) injury after cardiopulmonary bypass. METHODS: A cohort of patients undergoing coronary artery bypass grafting and/or valve procedures using cardiopulmonary bypass were administered a neurocognitive battery preoperatively and postoperatively at 6 hours and day 4. CRP, interleukin 1 beta, and interleukin 10 were quantified from serum. Increase of serum tau protein after surgery was used as a marker of axonal CNS damage. RESULTS: The rate of NCD was found to be 40.5% in this group. Surprisingly, known predictors of NCD did not differ significantly between patients with/without NCD. Patients with NCD had an early increase of CRP of a significantly higher magnitude than those without NCD (38.01 +/- 11.4 vs 16.49 +/- 3.5 mg/L, P = .042), interleukin 1ss (2.35 +/- 0.3 vs 1.20 +/- 0.2 pg/mL, P = .002), and interleukin 10 (29.77 +/- 4.7 vs 12.94 +/- 2.2 pg/mL, P < .001). Increase in serum Tau protein was significantly correlated to NCD (r = 0.50, P = .02). CONCLUSION: Perioperative increases in CRP and inflammatory cytokines are associated with NCD in patients after cardiopulmonary bypass. Thus, it appears that inflammation plays a key role in NCD pathophysiology, likely via axonal CNS injury, and could become a target for prevention.

Aged↗

PubMed2006

Bradykinin induces microvascular preconditioning through the opening of calcium-activated potassium channels.

BACKGROUND: This study was designed to investigate whether the activation of calcium-activated potassium (K(Ca)) or adenosine triphosphate sensitive potassium (K(ATP)) channels are required for bradykinin-induced microvascular preconditioning. METHODS: Isolated rabbit hearts underwent retrograde perfusion with Krebs-Henseleit buffer (KHB) followed by 60 minutes of ischemic arrest with cold crystalloid cardioplegia (CCCP). Eight CCCP hearts received no pretreatment. Six bradykinin-preconditioned hearts received a 10-minute coronary infusion of 10(-8) mol/L bradykinin-enriched KHB followed by a 5-minute recovery period before CCCP. Six hearts received both 10(-8) mol/L charybdotoxin (a K(Ca) channel blocker) and bradykinin preconditioning. Finally, 6 other hearts received 10(-5 degrees ) mol/L glibenclamide (a K(ATP) channel blocker) to bradykinin-enriched KHB. All hearts were reperfused for 30 minutes with KHB. RESULTS: Bradykinin preconditioning significantly improved the recovery of left ventricular and microvascular function, as compared with control. On the other hand, bradykinin preconditioning significantly reduced the contractile responses to U46619, a thromboxane A2 analogue. Charybdotoxin significantly inhibited the improved recovery of bradykinin-induced left ventricular and microvascular function. Glibenclamide tended to diminish the bradykinin preconditioning-enhanced recovery of left ventricular function, but failed to affect bradykinin preconditioning-improved recovery of microvascular function. CONCLUSION: Both K(Ca) and K(ATP) channels were involved partially in bradykinin-induced myocardial preconditioning. However, bradykinin induces microvascular preconditioning through the opening of K(Ca) channels rather than K(ATP) channels.

Adenosine Triphosphate↗

PubMed2006

Aprotinin in cardiac surgery.

Aprotinin is a naturally occurring serine protease inhibitor that is being used with increasing frequency in cardiac surgery and beyond to reduce blood loss and the need for perioperative blood transfusion. Through inhibition of serine proteases such as plasmin, aprotinin significantly reduces fibrinolysis, thereby aiding hemostasis during surgical procedures. In addition, aprotinin interacts with other factors in the coagulation and fibrinolytic cascade, creating a hemostatic balance, without increasing the risk of thrombosis. These proven benefits are supplemented by the anti-inflammatory properties of aprotinin, which may help curb some of the deleterious effects of cardiopulmonary bypass. This article will review the discovery of aprotinin, its mechanism of action, dosing and adverse effects, and highlight the major recent trials demonstrating its efficacy.

Animals↗

PubMed2005

Bradykinin preconditioning improves the profile of cell survival proteins and limits apoptosis after cardioplegic arrest.

BACKGROUND: We hypothesized that preconditioning the heart with bradykinin (BK) would improve the profile of antiapoptotic proteins and inhibit myocardial apoptosis. METHODS AND RESULTS: Eighteen rabbit hearts were retrogradely perfused with Krebs-Henseleit buffer (KHB). Six control hearts were perfused with KHB for 90 minutes without cardioplegia ischemia. Six hearts were arrested for 30 minutes (37 degrees C) with crystalloid cardioplegia (CCP). Six BK preconditioning (BKPC) hearts received a 10-minute coronary infusion of 10(-8) M BK-enriched KHB followed by a 5-minute recovery period and were then arrested for 30 minutes with CCP. The hearts were reperfused for 30 minutes with KHB. BKPC significantly improved the recovery of left ventricular pressure (73+/-5 versus 51+/-4 mm Hg; P<0.05) and reduced the percentage of myocardial apoptosis (3.4+/-0.3% versus 1.2+/-0.2%; P<0.05) as compared with CCP. There were no significant differences in total protein levels of caspase 3, Bcl-2, Bad, and Bax, among the groups. Both BKPC and CCP induced phosphorylation of Bad at Ser112, but the BKPC group had higher phosphorylated Bad than CCP (4.4+/-0.5 versus 2.0+/-0.3; P<0.05). Both BKPC and CCP alone increased caspase 3 cleavage and activity as compared with controls (P<0.05 and P<0.01, respectively), but BKPC caused less cleavage and activation of caspase 3 than CCP alone (P<0.05). CONCLUSIONS: BKPC increased Bad phosphorylation, inhibited caspase 3 activation, and limited myocardial apoptosis, which were associated with improvement of left-ventricular performance. These results identify novel molecular mechanisms underlying the protective effects of BKPC during cardiac surgery.

Animals↗

PubMed2005

Aprotinin preserves cellular junctions and reduces myocardial edema after regional ischemia and cardioplegic arrest.

BACKGROUND: Cardiac surgery with cardiopulmonary bypass (CPB) and cardioplegic arrest has been associated with myocardial edema attributable to vascular permeability, which is regulated in part by thrombin-induced alterations in cellular junctions. Aprotinin has been demonstrated to prevent activation of the thrombin protease-activated receptor, and we hypothesized that aprotinin preserves myocardial cellular junctions and prevents myocardial edema in a porcine model of regional ischemia and cardioplegic arrest. METHODS AND RESULTS: Fourteen pigs were subjected to 30 minutes of regional ischemia, followed by 60 minutes of CPB, with 45 minutes of crystalloid cardioplegia, then 90 minutes of post-CPB reperfusion. The treatment group (n=7) was administered aprotinin (40,000 kallikrein inhibitor units [KIU]/kg loading dose, 40,000 KIU/kg pump prime, and 10,000 KIU/kg per hour continuous infusion). Control animals (n=7) received normal saline. Myocardial vascular endothelial (VE)-cadherin, beta-catenin and gamma-catenin, and associated mitogen-activated protein kinase (MAPK) pathways were assessed by immunoblot and immunoprecipitation. Histologic analysis of the cellular junctions was done by immunofluorescence. Myocardial tissue water content was measured. VE-cadherin, beta-catenin, and gamma-catenin levels were significantly greater in the aprotinin group (all P<0.05). Immunfluorescence confirmed that aprotinin prevented loss of coronary endothelial adherens junction continuity. Aprotinin reduced tyrosine phosphorylation in myocardial tissue sections. Phospho-p38 activity was approximately 30% lower in the aprotinin group (P=0.007). The aprotinin group demonstrated decreased myocardial tissue water content (81.2+/-0.5% versus 83.5+/-0.3%; P=0.01) and reduced intravenous fluid requirements (2.9+/-0.2 L versus 4.0+/-0.4 L; P=0.03). CONCLUSIONS: Aprotinin preserves adherens junctions after regional ischemia and cardioplegic arrest through a mechanism potentially involving the p38 MAPK pathway, resulting in preservation of the VE barrier and reduced myocardial tissue edema.

Adherens Junctions↗

PubMed2005

Molecular indices of apoptosis after intermittent blood and crystalloid cardioplegia.

BACKGROUND: We investigated whether intermittent blood and crystalloid cardioplegia differentially affect myocardial apoptosis and apoptosis gene-related proteins. METHODS AND RESULTS: Rabbit hearts were perfused with Krebs-Henseleit buffer on a Langendorff apparatus. Control hearts (n=6) were perfused for 120 minutes without cardioplegic ischemia. Hearts were arrested for 60 minutes with warm (37 degrees C) crystalloid cardioplegia (iW-CCP) (n=8) or with warm blood cardioplegia (iW-BCP) (n=8) administered intermittently. In cold (0 to 4 degrees C) groups, hearts were arrested for 60 minutes with cold crystalloid cardioplegia (iC-CCP; n=8) or with cold blood cardioplegia (iC-BCP; n=6) administered intermittently. The hearts were reperfused for 30 minutes with Krebs-Henseleit buffer. iC-BCP significantly preserved the recovery of left ventricular and microvascular function compared with the other 3 experimental groups. There were no significant differences in total protein levels of caspase 3, Bcl-2, Bad, and Bax among the groups. iC-BCP significantly induced greater phosphorylation of Bad (5.6+/-0.8-fold) as compared with the other 3 groups (3.4+/-0.6-fold in iC-CCP, P<0.05; 2.5+/-0.3 in iW-BCP, P<0.05; and 1.4+/-0.2 in iW-CCP, P<0.01). iC-BCP induced less caspase 3 activation and apoptosis than the other 3 groups. CONCLUSIONS: iC-BCP is superior to the other cardioplegic solutions in increasing the phosphorylation of Bad, inhibiting the activation of caspase 3, and preventing apoptosis. These effects of iC-BCP were associated with preserved left ventricular function and endothelium-dependent relaxation of coronary microvessels.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

PubMed2005

Effects of L-arginine on fibroblast growth factor 2-induced angiogenesis in a model of endothelial dysfunction.

BACKGROUND: Nitric oxide availability, which is decreased in advanced coronary artery disease associated with endothelial dysfunction, is an important mediator of fibroblast growth factor-2 (FGF-2)-induced angiogenesis. This could explain the disappointing results of FGF-2 therapy in clinical trials despite promising preclinical studies. We examined the influence of L-arginine supplementation to FGF-2 therapy on myocardial microvascular reactivity and perfusion in a porcine model of endothelial dysfunction. METHODS AND RESULTS: Eighteen pigs were fed either a normal (NORM, n=6) or high cholesterol diet, with (HICHOL-ARG, n=6) or without (HICHOL, n=6) L-arginine. All pigs underwent ameroid placement on the circumflex artery and 3 weeks later received surgical FGF-2 treatment. Four weeks after treatment, endothelial-dependent coronary microvascular responses and lateral myocardial perfusion were assessed. Endothelial cell density was determined by immunohistochemistry. FGF-2, fibroblast growth receptor-1, endothelial-derived nitric oxide synthase (eNOS), inducible nitric oxide synthase (iNOS), and syndecan-4 levels were determined by immunoblotting. Pigs from the HICHOL group showed endothelial dysfunction in the circumflex territory, which was normalized by L-arginine supplementation. FGF-2 treatment was ineffective in the HICHOL group (circumflex/left anterior descending blood flow ratios: 1.01 (rest) and 1.01 (pace), after and before treatment). Addition of L-arginine improved myocardial perfusion in response to FGF-2 at rest (ratio 1.13, P=0.02 versus HICHOL) but not during pacing (ratio 0.94, P=NS), and was associated with increased protein levels of iNOS and eNOS. CONCLUSIONS: L-arginine supplementation can partially restore the normal response to endothelium-dependent vasorelaxants and myocardial perfusion in response to FGF-2 treatment in a swine model of hypercholesterolemia-induced endothelial dysfunction. These findings suggest a role for L-arginine in combination with FGF-2 therapy for end-stage coronary artery disease.

Angiogenesis Inducing Agents↗

PubMed2005

Bradykinin preconditioning preserves coronary microvascular reactivity during cardioplegia-reperfusion.

BACKGROUND: Alterations of microvascular reactivity reduce myocardial perfusion after ischemic cardioplegia. We hypothesized that bradykinin preconditioning (BKPC) would preserve endothelium-dependent microvascular responses and improve myocardial function after cardioplegic ischemia-reperfusion. METHODS: Rabbit hearts were perfused with Krebs-Henseleit buffer (KHB). The hearts were arrested for 60 minutes with moderately cold (25 degrees C) crystalloid cardioplegia (MCCP, n = 8) or with cold (0 degrees to 4 degrees C) crystalloid cardioplegia (CCCP) (n = 6). The BKPC hearts received a 10-minute coronary infusion of 10(-8) M BK-enriched KHB, followed by a 5-minute recovery period, and then were arrested for 60 minutes with MCCP (BKPC + MCCP, n = 8) or with CCCP (BKPC + CCCP, n = 6). The hearts were reperfused for 30 minutes with KHB. Six control hearts were perfused with KHB for 90 minutes without cardioplegia-ischemia. Left ventricle performance was measured, and in vitro relaxation responses of precontracted coronary arterioles (internal diameter, 80 to 150 mum) were obtained in a pressurized no-flow state. RESULTS: Ischemic arrest with MCCP or CCCP markedly reduced endothelium-dependent relaxation to adenosine 5'-diphosphate, substance P, and calcium ionophore (A23187). Both MCCP and CCCP significantly enhanced contractile responses to U46619 (10(-7) M), a thromboxane A2 analogue, compared with control (p < 0.05). In contrast, BKPC significantly improved the recovery of endothelium-dependent relaxation to adenosine 5'-diphosphate, substance P, and A23187 compared with MCCP or CCCP, respectively. BKPC reduced the contractile responses to U46619 compared with MCCP or CCCP. BKPC also improved postischemic performance compared with MCCP or CCCP alone (p < 0.05). CONCLUSIONS: BKPC preserves endothelium-dependent microvascular responses and prevents the hypercontractility to U46619. These effects may provide increased coronary perfusion and prevent arteriolar spasm after open heart surgery. They suggest that BK preconditions the coronary microvasculature during cardiovascular surgery.

Animals↗

PubMed2005

Aprotinin inhibits protease-dependent platelet aggregation and thrombosis.

BACKGROUND: Hemostatic effects of the protease inhibitor aprotinin in cardiac surgery are well described, and recent evidence suggests an antithrombotic mechanism of aprotinin through inhibition of thrombin-mediated platelet activation. We hypothesized that aprotinin provides hemostasis while reducing vascular thrombosis by attenuating protease-dependent platelet function. METHODS: Rabbits (3 to 4 kg) underwent carotid artery thrombosis induced by electrical current. Treatment animals (n = 8) received aprotinin by a 100,000-KIU bolus followed by a continuous infusion (25,000 KIU/h). Control animals (n = 8) received crystalloid solution. Thrombus weight and time to thrombotic occlusion were determined. Platelet aggregation was examined in response to protease-dependent (thrombin) and protease-independent (adenosine diphosphate, ADP) platelet agonists. Platelet thrombin protease-activated receptor (PAR) expression was analyzed by Western blot. Ear bleeding time and abdominal incisional bleeding were measured at baseline and serially. RESULTS: Thrombus weight was decreased by aprotinin (6.1 +/- 1.1 mg versus 10.8 +/- 1.5 mg, aprotinin versus control, p < 0.05). Time to thrombotic occlusion was prolonged in the aprotinin group (17.4 +/- 1.0 minutes versus 8.3 +/- 1.3 minutes, p < 0.001). Rabbit platelet expression of thrombin PARs was demonstrated by Western blot analysis, and was not altered by aprotinin therapy. Platelet aggregation due to thrombin was decreased by aprotinin therapy (59.2% +/- 3.0% versus 95.8% +/- 1.5%, p < 0.001), whereas protease-independent, ADP-induced platelet aggregation was unchanged with aprotinin. Incisional bleeding was not different between groups. In the aprotinin group, bleeding time was unchanged at baseline and then reduced for the duration of the experiment (35.0 +/- 4.7 seconds versus 76.8 +/- 6.4 seconds, p < 0.05). CONCLUSIONS: While providing hemostatic effects, aprotinin attenuates vascular thrombosis in part by inhibition of PAR activation, resulting in the prevention of thrombin-induced platelet aggregation.

Animals↗

PubMed2005

Normalization of coronary microvascular reactivity and improvement in myocardial perfusion by surgical vascular endothelial growth factor therapy combined with oral supplementation of l-arginine in a porcine model of endothelial dysfunction.

OBJECTIVE: Vascular endothelial growth factor acts in part through nitric oxide release, the availability of which is decreased in endothelial dysfunction associated with advanced coronary artery disease. This could explain the relatively disappointing results of vascular endothelial growth factor therapy in clinical studies compared with animal studies. We examined the influence of L-arginine supplementation to vascular endothelial growth factor therapy on myocardial microvascular reactivity and perfusion in a porcine model of endothelial dysfunction. METHODS: Twenty-four pigs were fed either a normal (NORM, n = 8) or high-cholesterol diet with (CHOL-ARG, n = 8) or without (CHOL, n = 8) L-arginine. All pigs underwent ameroid placement on the circumflex artery and then 3 weeks later received surgical vascular endothelial growth factor treatment. Four weeks after treatment, endothelial-dependent coronary microvascular responses and lateral myocardial perfusion were assessed. Endothelial cell density was determined by means of immunohistochemistry. Vascular endothelial growth factor, endothelial nitric oxide synthase, and Akt levels were determined by means of immunoblotting. RESULTS: Pigs from the CHOL group showed endothelial dysfunction in the circumflex territory, which was normalized by L-arginine supplementation. Vascular endothelial growth factor treatment was ineffective in the CHOL group (circumflex/left anterior descending coronary artery blood flow ratios: 0.95 [rest] and 0.74 [pace] before-after treatment; P < .05 compared with the NORM group). Addition of L-arginine restored the angiogenic effect of vascular endothelial growth factor (ratios: 1.13 [rest] and 1.20 [pace]; P < .05) and was associated with increased endothelial cell density, as well as vascular endothelial growth factor, endothelial nitric oxide synthase, and Akt protein levels in the ischemic territory. CONCLUSIONS: L-Arginine supplementation can restore normal endothelium-dependent vasorelaxation and angiogenic response to vascular endothelial growth factor in a swine model of chronic myocardial ischemia with hypercholesterolemia-induced endothelial dysfunction. These findings suggest a putative role for L-arginine in combination with vascular endothelial growth factor therapy for end-stage coronary artery disease.

Administration, Oral↗

PubMed2005

Effects of L-arginine on the endogenous angiogenic response in a model of hypercholesterolemia.

BACKGROUND: The angiogenic properties of vascular endothelial growth factor and fibroblast growth factor-2 are mediated in part through nitric oxide release, whose availability is decreased in endothelial dysfunction associated with advanced coronary artery disease. We examined the influence of L-arginine supplementation on the endogenous angiogenic response to ischemia in a porcine model of hypercholesterolemia. METHODS: Eighteen Yucatan pigs were fed either a normal (NORM, n=6) or a high-cholesterol diet, with (CHOL-ARG, n=6) or without (CHOL, n=6) L-arginine (100 mg/kg/day), throughout the experiment. All pigs underwent ameroid constrictor placement on the circumflex artery (LCx). Seven weeks later, endothelium-dependent coronary microvascular responses to fibroblast growth factor-2 and vascular endothelial growth factor were assessed by videomicroscopy. Perfusion was assessed with radioactive microspheres; angiogenesis was evaluated by platelet-endothelial cell adhesion molecule-1 (CD-31) staining. Regional myocardial function was assessed by sonomicrometry. Expression of endothelial nitric oxide synthase and inducible nitric oxide synthase was measured by Western blot analyses. RESULTS: Pigs from the CHOL group showed significant endothelial dysfunction in the LCx territory. The dysfunction was normalized partially by L-arginine supplementation, which restored the response in the LCx territory to the level of the nonischemic anterior wall. L-arginine supplementation resulted in increases of perfusion, density of capillary endothelial, and level of endothelial nitric oxide synthase in the ischemic region. Despite these findings, no improvement in myocardial regional function was found. CONCLUSIONS: L-arginine supplementation can partially restore endothelium-dependent vasorelaxation and improve myocardial perfusion in a swine model of chronic myocardial ischemia with hypercholesterolemia-induced endothelial dysfunction. These findings suggest a putative role for L-arginine in combination with growth factor therapy for end-stage coronary artery disease.

Animals↗

PubMed2004

Differences in gene expression profiles of diabetic and nondiabetic patients undergoing cardiopulmonary bypass and cardioplegic arrest.

BACKGROUND: Diabetes mellitus is an independent risk factor for early postoperative mortality and complications after coronary artery bypass grafting (CABG). We sought to compare the cardiac gene expression responses to cardiopulmonary bypass (CPB) and cardioplegic arrest (C) in patients with and without diabetes. METHODS AND RESULTS: Twenty atrial myocardium samples were harvested from 5 type II insulin-dependent diabetic and 5 matched nondiabetic patients undergoing CABG, before and after CPB/C. Oligonucleotide microarray analyses of 12625 genes were performed on the 10 sample pairs using matched pre-CPB tissues as controls. Array results were validated with Northern blotting and immunoblotting. Compared with pre-CPB/C, post-CPB/C myocardial tissues revealed 851 upregulated and 480 downregulated genes with a threshold P< or =0.025 (signal-to-noise ratio, 4.04) in the diabetic group, compared with 480 upregulated and 626 downregulated genes (signal-to-noise ratio, 3.04) in the nondiabetic group (P<0.001). There were 18 genes that were upregulated >4-fold in diabetic and nondiabetic patients (including inflammatory/transcription activators FOS, CYR 61, and IL-6, apoptotic gene NR4A1, stress gene DUSP1, and glucose-transporter gene SLC2A3). However, 28 genes showed such marked upregulation in the diabetic group exclusively (including inflammatory/transcription activators MYC, IL8, IL-1beta, growth factor vascular endothelial growth factor, amphiregulin, and glucose metabolism-involved gene insulin receptor substrate 1), and 27 genes in the nondiabetic group only, including glycogen-binding subunit PPP1R3C. CONCLUSIONS: Gene expression profile after CPB/C is quantitatively and qualitatively different in patients with diabetes. These results have important implications for the design of tailored myocardial protection and operative strategies for diabetic patients undergoing CPB/C.

Actins↗

PubMed2004

Improved profile of bad phosphorylation and caspase 3 activation after blood versus crystalloid cardioplegia.

BACKGROUND: Expression of Bcl-2 family proteins and activation of terminal caspase 3 are important for ischemia-reperfusion-induced apoptosis. Bad and Bax are pro-apoptotic proteins, whereas, phosphorylation of Bad inhibits its binding to and inactivation of anti-apoptotic Bcl-2. Thus, decreases in phospho-Bad would be proapoptotic. We investigated if blood (BCP) or crystalloid cardioplegia (CCP) differentially affects apoptosis gene-related proteins. METHODS: Rabbit hearts were perfused with Krebs-Henseleit buffer (KHB) on a Langendorff apparatus. Control hearts (n = 6) were perfused for 90 minutes without cardioplegic ischemia. In the other two groups, hearts were arrested for 30 minutes (37 degrees C) with BCP (n = 6) or with CCP (n = 6) administered continuously (1.5 mL/min). The hearts were reperfused for 30 minutes with KHB. Left ventricle (LV) performance was measured before cardioplegic arrest and at 30 minutes of reperfusion. In vitro relaxation responses of precontracted microvessels (100-180 microm) were obtained in a pressurized no-flow state. Total and activated or phosphorylated caspase 3, Bcl-2, Bad, and Bax were measured by quantitative immunoblotting using specific antibodies. RESULTS: Blood cardioplegia significantly improved the recovery of LV developed pressure compared to CCP (p < 0.05). The endothelium-dependent relaxation in response to adenosine 5'-diphosphate was greater after BCP than after CCP (59.9 +/- 4% vs 26.9 +/- 6%, respectively; p < 0.05). There were no differences in total protein levels of caspase 3, Bcl-2, Bad, and Bax between the groups. Both BCP and CCP increased caspase 3 activity as compared with controls, but CCP caused more activation of caspase 3 than BCP (6.2 +/- 0.7 fold vs 3.1 +/- 0.4, p < 0.05). Both BCP and CCP induced phosphorylation of Bad at Ser(112), but BCP caused greater phosphorylation of Bad (3.5 +/- 0.2 fold vs 2.0 +/- 0.12 fold, respectively, p < 0.05) than CCP. CONCLUSIONS: Blood cardioplegia is superior to CCP in inhibiting the activation of caspase 3 and in increasing phospho-Bad. These actions of BCP were associated with improved LV function and endothelium-dependent relaxation of coronary microvessels. These results may provide molecular mechanisms by which to improve myocardial protection during cardiac surgery.

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