Biomedical subjects

L Minutoli

Publications and source records attributed to L Minutoli.

14 recordsLinked to original sources

PubMed2001

Oxidative stress causes nuclear factor-kappaB activation in acute hypovolemic hemorrhagic shock.

Nuclear Factor kappaB (NFkappaB) is an ubiquitous rapid response transcription factor involved in inflammatory reactions and exerts its action by expressing cytokines, chemokines, and cell adhesion molecules. We investigated the role of NF-kappaB in acute hypovolemic hemorrhagic (Hem) shock. Hem shock was induced in male anesthetized rats by intermittently withdrawing blood from an iliac catheter over a period of 20 min (bleeding period) until mean arterial blood pressure (MAP) fell and stabilized within the range of 20-30 mmHg. Hemorrhagic shocked rats died in 26.3 +/- 2.1 min following the discontinuance of bleeding, experienced a marked hypotension (mean arterial blood pressure = 20-30 mmHg) and had enhanced plasma levels of Tumor Necrosis Factor-alpha (200 +/- 15 pg/ml, 20 min after the end of bleeding). Furthermore, aortas taken 20 min after bleeding from hemorrhagic shocked rats showed a marked hypo-reactivity to phenylephrine (PE; 1nM to 10 microM) compared with aortas harvested from sham shocked rats. Hem shocked rats also had increased levels of TNF-alpha mRNA in the liver (15-20 min after the end of bleeding) and enhanced plasma levels of 2,5-dihydroxybenzoic acid (2,5-DHBA; 6 +/- 2.2 microm), 2,3-dihydroxybenzoic acid (2,3-DHBA; 13 +/- 2.1 microm), both studied to evaluate OH(*) production. Electrophoretic mobility shift assay showed that liver NF-kappaB binding activity increased in the nucleus 10 min after the end of hemorrhage and remained elevated until the death of animals. Western blot analysis suggested that the levels of inhibitory IkappaBalpha protein in the cytoplasm became decreased at 5 min after the end of bleeding. IRFI-042, a vitamin E analogue (20 mg/kg intraperitoneally 2 min after the end of bleeding), inhibited the loss of IkappaBalpha protein from the cytoplasm and blunted the increase in NF-kappaB binding activity. Furthermore IRFI-042 increased survival time (117.8 +/- 6.51 min; p <.01) and survival rate (vehicle = 0% and IRFI-042 = 80%, at 120 min after the end of bleeding), reverted the marked hypotension, decreased liver mRNA for TNF-alpha, reduced plasma TNF-alpha (21 +/- 4.3 pg/ml), and restored to control values the hypo-reactivity to PE. Our results suggest that acute blood loss (50% of the estimated total blood volume over a period of 20 min) causes early activation of NF-kappaB, likely through an increased production of reactive oxygen species. This experiment indicates that NF-kappaB-triggered inflammatory cascade becomes early activated during acute hemorrhage even in the absence of resuscitation procedures.

Animals↗

PubMed2001

The phytoestrogen alpha-zearalenol reverses endothelial dysfunction induced by oophorectomy in rats.

It has been shown recently that alpha-zearalenol, a resorcyclic acid lactone, prevents bone loss in a rat model of postmenopausal bone loss. We have therefore investigated the effects of this phytoestrogen on endothelial dysfunction induced by estrogen deficiency in rats. Female mature Sprague-Dawley rats underwent a bilateral oophorectomy (OVX rats). Sham-operated animals (sham OVX rats) were used as controls. Three weeks after surgery, animals were randomized to the following treatments: alpha-zearalenol (1 mg/kg/day, i.m., for 4 weeks), 17beta-estradiol (20 microg/kg/day, i.m., for 4 weeks), or their vehicle (100 microl, i.m., of cottonseed oil). Two other groups of rats were treated with alpha-zearalenol or 17beta-estradiol plus the pure estrogen receptor antagonist ICI 182780 (2.5 mg/kg/day, i.m., for 4 weeks). Mean arterial blood pressure (MAP), heart rate (HR), total plasma cholesterol, plasma estradiol, and plasma alpha-zearalenol were studied. We also investigated endothelial-dependent (acetylcholine, 10 nM to 10 microM) and endothelial-independent (sodium nitroprusside, 15 nM to 30 nM) relaxation of aortic rings, as well as N(G)-methyl-L-arginine (L-NMA: 10 to 100 microM)-induced vasoconstriction and calcium-dependent nitric oxide synthase (cNOS) activity in homogenates of lungs taken from both sham OVX rats and OVX rats. Untreated OVX rats had, compared with sham OVX animals, unchanged body weight, MAP, HR, and plasma cholesterol. In contrast oophorectomy reduced plasma estradiol levels (OVX, 2 +/- 0.5 pg/ml; sham OVX, 35 +/- 6 pg/ml), impaired endothelial-dependent relaxation and blunted L-NMA-induced contraction (L-NMA 100 microM: sham OVX, 2.7 +/- 0.3 g/mg tissue; OVX, 1.3 +/- 0.1 g/mg tissue). Moreover OVX rats showed a reduced calcium-dependent NO synthase (cNOS) activity. Treatment with alpha-zearalenol or with 17beta-estradiol reverted the endothelial dysfunction and increased cNOS activity in lung homogenates. These effects were abolished by the pure estrogen receptor antagonist ICI 182780. Our data suggest that alpha-zearalenol improves endothelial-dependent relaxation in OVX rats through an estrogen receptor-mediated effect.

Acetylcholine↗

PubMed2001

Cardiovascular effects of raloxifene hydrochloride.

Raloxifene hydrochloride binds to the estrogen receptor and shows tissue-selective effects; thus, it belongs to a class of drugs recently described as selective estrogen receptor modulators (SERMs). Tissue selectivity of raloxifene may be achieved through several mechanisms: the ligand structure, interaction of the ligand with different receptor subtypes in various tissues, and intracellular events after ligand binding. Raloxifene has estrogen-agonist effects on bone and lipids and estrogen antagonist effects on the breast and uterus. In addition to its well established effects on osteoporosis, recent preclinical and clinical findings suggest that raloxifene also possesses beneficial effects on the cardiovascular system. These findings indicated that raloxifene may have cardioprotective properties without an increased risk of cancer or other side effects. Raloxifene has been shown to reduce total and low-density lipoprotein cholesterol concentrations in plasma, an effect similar to that produced by estrogens. Unlike estrogens, however, raloxifene does not increase high-density lipoprotein cholesterol and triglyceride levels in plasma. Endothelium is thought to play an important role in the genesis of atherosclerosis. Several lines of evidence suggest that an intervention with endothelial function might influence the progression of coronary disease and the incidence of cardiovascular events. Raloxifene increases the nitric oxide/endothelin-1 ratio, and improves endothelium-dependent vasomotion in post-menopausal women to the same extent as estrogens. Furthermore, in two randomized trials on post-menopausal women raloxifene reduced homocysteine levels, another independent risk factor for the development of cardiovascular disease. Although estrogens remain the drugs of choice in the hormonal therapy of most postmenopausal women, raloxifene may represent and alternative in women who are at risk of coronary artery disease.

Animals↗

PubMed2000

The reduction of myocardial damage and leukocyte polymorphonuclear accumulation following coronary artery occlusion by the tyrosine kinase inhibitor tyrphostin AG 556.

We investigated the effects of tyrophostin AG 556, a tyrosine kinase inhibitor, on the phenomenon of leukocyte accumulation during ischaemia and reperfusion of the myocardium. Male anaesthetized rats were subjected to total occlusion (45 min) of the left main coronary artery followed by 5 h reperfusion (MI/R). Sham myocardial ischaemia-reperfusion rats (Sham MI/R) were used as controls. Myocardial necrosis, myocardial myeloperoxidase activity (MPO), serum creatinine phosphokinase activity (CPK) serum Tumor Necrosis Factor (TNF-alpha) and Interleukin 6 (IL-6), cardiac intercellular adhesion molecule-1 (ICAM-1) and TNF-alpha expression and myocardial contractility (left ventricle dP/dt(max)) were evaluated. Myocardial ischaemia plus reperfusion in untreated rats produced marked myocardial necrosis, increased serum CPK activity (196.5 +/- 19 U/100 ml, at the end of reperfusion) and myeloperoxidase activity (MPO, a marker of leukocyte accumulation) both in the area-at-risk (4.5 +/- 0.5 U/g/tissue) and in necrotic area (8.2 +/- 1.2 U/g/tissue), reduced myocardial contractility (1,706 +/- 52 mmHg/s, at the end of reperfusion) and induced a marked increase in the serum levels of TNF-alpha (1,950 +/- 97 pg/ml, at 1 h of reperfusion) and IL-6 (998 +/- 16 U/ml, at the end of reperfusion). Finally, myocardial ischaemia-reperfusion injury also increased cardiac mRNA for TNF-alpha and ICAM-1 in the myocardium-at risk. Tyrphostin AG 556 (0.5, 1 and 2 mg/kg subcutaneously 5 min after the onset of reperfusion) lowered myocardial necrosis and myeloperoxidase activity in the area-at-risk (1.5 +/- 0.2 U/g/tissue, following the highest dose) and in necrotic area (2.9 +/- 0.3 U/g/tissue following the highest dose), decreased serum CPK activity (96 +/- 9 U/100 ml, at the end of reperfusion), lowered serum TNF-alpha and IL-6, increased myocardial contractility (2,096 +/- 88 mmHg s, at the end of reperfusion) and reduced cardiac mRNA levels for TNF-alpha and ICAM-1. The present data suggest that tyrosine kinase inhibitors protect against myocardial ischaemia-reperfusion injury by reducing leukocyte accumulation to the ischaemic myocardium.

Animals↗

PubMed2000

IRFI 042, a novel dual vitamin E-like antioxidant, inhibits activation of nuclear factor-kappaB and reduces the inflammatory response in myocardial ischemia-reperfusion injury.

BACKGROUND: Nuclear factor-kappaB (NF-kappaB) is a ubiquitous rapid response transcription factor involved in inflammatory reactions which exerts its effect by expressing cytokines, chemokines, and cell adhesion molecules. Oxidative stress causes NF-kappaB activation. IRFI 042 is a novel dual vitamin E-like antioxidant and we, therefore, investigated its ability to protect the heart from oxidative stress and to halt the inflammatory response in a model of myocardial ischaemia-reperfusion injury. METHODS: Anaesthetized rats were subjected to total occlusion (45 min) of the left main coronary artery followed by 5-h reperfusion (MI/R). Sham myocardial ischaemia rats (sham-operated rats) were used as controls. Myocardial necrosis, cardiac output, cardiac and plasma vitamin E levels, myocardial malondialdehyde (MAL), cardiac SOD activity and elastase content (an index of leukocyte infiltration), hydroxyl radical (OH&z.ccirf;) formation, cardiac amount of mRNA codifying for ICAM-1 (evaluated by the means of reverse transcriptase polymerase chain reaction) and ICAM-1 immunostaining in the at-risk myocardium were investigated. NF-kappaB activation and the inhibitory protein of NF-kappaB, I-kappaBalpha, were also studied in at-risk myocardium by using electrophoretic mobility shift assay (EMSA) and Western blot analysis, respectively. RESULTS: The ischaemia-reperfusion model produced wide heart necrosis (area at risk-necrotic area=52+/-5%; necrotic area-left ventricle=28+/-3%), increased cardiac MAL, an index of lipid peroxidation (area at risk=62.5+/-3.9 nmol/g tissue; necrotic area=80.3+/-5.1 nmol/g tissue), induced tissue neutrophil infiltration, and caused a marked decrease in endogenous antioxidants. Furthermore, myocardial ischaemia plus reperfusion caused in the area at risk peak message for ICAM-1 at 3 h of reperfusion and increased cardiac ICAM-1 immunostaining at 5 h of reperfusion. NF-kappaB activation was also evident at 0.5 h of reperfusion and reached its maximum at 2 h of reperfusion. I-kappaBalpha was markedly decreased at 45 min of occlusion; peak reduction was observed at 1 h of reperfusion and thereafter it was gradually restored. Intraperitoneal administration of IRFI 042 (5, 10, 20 mg/kg, 5 min after reperfusion) reduced myocardial necrosis expressed as a percentage either of the area at risk (18+/-4%) or the total left ventricle (11+/-2%), and improved cardiac output. This treatment also limited membrane lipid peroxidation in the area at risk (MAL=14.3+/-2.5 nmol/g tissue) and in the necrotic area (MAL=26.5+/-3.7 nmol/g tissue), restored the endogenous antioxidants vitamin E and superoxide dismutase, and inhibited detrimental hydroxyl radical formation. Finally, IRFI 042 blocked the activation of NF-kappaB, reduced cardiac ICAM-1 expression, and blunted tissue elastase content, an index of leukocytes accumulation at the site of injury. CONCLUSIONS: Our data suggest that IRFI 042 is cardioprotective during myocardial infarction by limiting reperfusion-induced oxidative stress and by halting the inflammatory response.

Analysis of Variance↗

PubMed2000

Genistein supplementation and estrogen replacement therapy improve endothelial dysfunction induced by ovariectomy in rats.

BACKGROUND: We investigated the effect of genistein, a phytoestrogen derived from a soy diet with a flavonoid chemical structure, on endothelial dysfunction induced by estrogen deficiency in rats. METHODS: Female mature Sprague-Dawley rats were subjected to a bilateral ovariectomy (OVX rats). Sham-operated animals (Sham OVX rats) were used as controls. Three weeks after surgery animals were randomized to the following treatments: genistein (0.2 mg/kg/day, s.c. for 4 weeks), 17 beta-estradiol (20 micrograms/kg/day, s.c. for 4 weeks) or their respective vehicles. Mean arterial blood pressure (MAP), heart rate (HR), total plasma cholesterol, plasma estradiol, plasma genistein levels and uterine weights were studied. Furthermore, we investigated acetylcholine (ACh 10 nM-10 microM) and sodium nitroprusside: (SN 15-30 nM) induced relaxation of aortic rings as well as NG-L-arginine (L-NMA: 10-100 microM) induced vasoconstriction in phenylephrine precontracted aortic segments and calcium-dependent nitric oxide synthase (cNOS) activity in homogenates of lungs taken from both sham OVX and OVX rats. RESULTS: Untreated OVX rats had, compared with sham OVX animals, unchanged body weight, MAP, HR and plasma cholesterol. In contrast ovariectomy impaired endothelial responses, blunted L-NMA induced contraction (L-NMA 100 microM: Sham OVX = 2.1 +/- 0.2 g/mg tissue; OVX = 1.7 +/- 0.4 g/mg tissue) and reduced cNOS activity. Treatment with 17 beta-estradiol increased the hormone plasma levels, reverted the endothelial dysfunction and increased cNOS activity in lung homogenates. Genistein supplementation enhanced the circulating levels of the phytoestrogen and affected NOS activity and endothelial dysfunction to the same extent. CONCLUSIONS: Our data suggest that genistein and 17 beta-estradiol show overlapping effects on experimental endothelial dysfunction.

Acetylcholine↗

PubMed2000

Tacrolimus limits polymorphonuclear leucocyte accumulation and protects against myocardial ischaemia- reperfusion injury.

Intercellular adhesion molecule-1 (ICAM-1) plays an important role in the pathogenesis of either human and experimental myocardial ischaemia. Tacrolimus, formerly known as FK506, has been previously shown to display cardioprotective effects on experimental ischaemia/reperfusion-induced myocardial damage. This study investigated whether cardioprotection induced by tacrolimus in myocardial ischaemia-reperfusion (MI/R) injury might be due to inhibition of the nuclear factor kappa B (NF- kappaB) that in turn causes reduced cardiac ICAM-1 expression and blunted polymorphonuclear leukocyte accumulation. Anaesthetized rats were subjected to total occlusion (45 min) of the left main coronary artery followed by 5 h reperfusion (MI/R). Sham myocardial ischaemia-reperfusion rats (Sham MI/R) were used as controls. Myocardial necrosis, myocardial myeloperoxidase activity, serum creatine kinase (CK) activity, cardiac mRNA for ICAM-1 reverse-transcriptase polymerase chain reaction, the inhibitory protein of NF- kappaB I kappaB alpha (Western blot analysis) in the myocardium-at-risk, and left ventricle d P/d t(max)were evaluated. Myocardial ischaemia plus reperfusion in untreated rats produced marked myocardial necrosis, increased serum CK activity and myeloperoxidase activity (MPO, a marker of leukocyte accumulation) both in the area at risk and in the necrotic area, and reduced the left ventricle dP/d t(max). Furthermore, inhibitory protein I kappaB alpha levels decreased, and cardiac mRNA for ICAM-1 increased, after 0.5 and 5 h of reperfusion, respectively. Administration of tacrolimus (25, 50 and 100microg/kg as an i.v. infusion 5 min after reperfusion) lowered myocardial necrosis and myeloperoxidase activity in the area at risk and in necrotic area, decreased serum CK activity, increased left ventricle dP/d t(max), reduced the loss the of inhibitory protein I kappaB alpha and blunted the message for ICAM-1. The present data suggest that tacrolimus blocks the early activation of the transcription factor NF- kappaB, suppresses ICAM-1 gene activation, reduces leukocyte accumulation and protects against myocardial ischaemia-reperfusion injury.

Animals↗

PubMed2000

Protective effects of cyclosporin-A in splanchnic artery occlusion shock.

Cyclosporin A (CsA) is an immunosuppressant drug that inhibits nitric oxide (NO) synthase induction in vascular smooth muscle cells. Splanchnic artery occlusion (SAO) shock is a lethal type of shock characterized by a marked vascular dysfunction in which the L-arginine/nitric oxide pathway plays an important role. We investigated whether CsA exerts protective effects in SAO shock by interfering with the L-arginine/nitric oxide pathway. Male anaesthetized rats (n=156) were subjected to clamping of the splanchnic arteries for 45 min. This surgical procedure resulted in an irreversible state of shock (SAO shock). Sham operated animals were used as controls. SAO shocked rats had a decreased survival (86+/-6 min, while sham shocked rats survived more than 240 min), marked hypotension, increased serum levels of TNF-alpha, enhanced plasma nitrite/nitrate concentrations (75+/-7.1 microM; sham shocked rats=1.6+/-0.5 microM) and enhanced inducible NO synthase (iNOS) protein induction and activity in the aorta. Moreover aortic rings from shocked rats showed a marked hyporeactivity to phenylephrine (PE, 1 nM - 10 microM). CsA (0.25, 0.5 and 1 mg kg(-1), 5 min after reperfusion) increased survival rate (SAO+CsA=236+/-9 min following the highest dose), reverted the marked hypotension, reduced plasma nitrite/nitrate concentration (11+/-5.2 microM following the highest dose), restored to control values the hyporeactivity to PE, and blunted iNOS protein induction and activity in aortic rings. The present data indicate that in an experimental rat model CsA may have antishock properties related to inhibition of L-arginine/nitric oxide pathway.

Animals↗

PubMed1999

Effect of sulfatide on acute lung injury during endotoxemia in rats.

Experimental studies have shown that intrapulmonary leukocyte sequestration and activation is implicated in the pathogenesis of acute lung injury during endotoxemia. Selectins are involved in the adhesion of leukocyte to the endothelium. Sulfatide is recognized by P selectin and blocks this adhesion molecule. We studied the effects of sulfatide on endotoxin-induced lung damage in rats. Endotoxin shock was produced in male rats by a single intravenous (i.v.) injection of 20 mg/kg of Salmonella enteritidis lipopolysaccharide (LPS). LPS administration reduced survival rate (0%, 72 h after endotoxin challenge) decreased mean arterial blood pressure (MAP), produced leukopenia (Controls = 11,234+/-231 cells/mL, LPS = 4,567+/-123 cells/mL) and increased lung myeloperoxidase activity (MPO; a marker of leukocyte accumulation) in the lung (Controls = 0.35+/-0.1 U/g/tissue; LPS = 10+/-1.2 U/g/tissue). Furthermore LPS administration markedly impaired the concentration-response curves for acetylcholine and sodium nitroprusside in isolated pulmonary arterial rings. There was also an increased staining for P-selectin in the pulmonary arteries. Sulfatide treatment (10 mg/kg, 30 min. after LPS challenge), significantly protected against LPS-induced lethality (90% survival rate and 70% survival rate 24 h and 72 h after LPS injection), reduced LPS induced hypotension, reverted leukopenia (8,895+/-234 cells/ml) and lowered lung MPO activity (1.7+/-0.9 U/g/tissue). Furthermore sulfatide restored to control values the LPS-induced impairment in arterial pulmonary vasorelaxation and reduced P-selectin immunostaining. Our data indicate that sulfatide attenuates LPS-induced lung injury and protects against endotoxin shock.

Acute Disease↗

PubMed1999

Cardioprotection by the phytoestrogen genistein in experimental myocardial ischaemia-reperfusion injury.

1. Soybean phytoestrogens have no oestrogen agonist effects on the reproductive system and therefore it is reasonable to explore the potential of these naturally occurring plant oestrogens in the cardiovascular pathology. We therefore investigated the effects of genistein in a rat model of myocardial ischaemia-reperfusion injury. 2. Anaesthetized rats were subjected to total occlusion (45 min) of the left main coronary artery followed by 5 h reperfusion (MI/R). Sham operated rats were used as controls. Myocardial necrosis, myocardial myeloperoxidase activity (MPO), serum creatinine phosphokinase activity (CPK), serum and macrophage Tumour Necrosis Factor-alpha (TNF-alpha), cardiac intercellular adhesion molecule-1 (ICAM-1) immunostaining, cardiac mRNA for ICAM-1 evaluated by the means of reverse transcriptase polymerase chain reaction (RT - PCR), ventricular arrhythmias and myocardial contractility (left ventricle dP/dt(max)) were evaluated. 3. Myocardial ischaemia and reperfusion in untreated rats produced marked myocardial necrosis, increased serum CPK activity and MPO activity both in the area-at-risk and in the necrotic area, reduced myocardial contractility, caused ventricular arrhythmias and induced a marked increase in serum and macrophage TNF-alpha. Furthermore myocardial ischaemia-reperfusion injury increased ICAM-1 expression in the myocardium. 4. Administration of genistein (1 mg kg(-1), i.v., 5 min after coronary artery occlusion) lowered myocardial necrosis and MPO activity in the area-at-risk and in the necrotic area, decreased serum CPK activity, increased myocardial contractility, decreased the occurrence of ventricular arrhythmias, reduced serum and macrophages levels of TNF-alpha and blunted ICAM-1 expression in the injured myocardium. Finally genistein added in vitro to peritoneal macrophages collected from untreated rats subjected to myocardial ischaemia-reperfusion injury significantly reduced TNF-alpha production. 5. Our data suggest that genistein limits the inflammatory response and protects against myocardial ischaemia-reperfusion injury.

Animals↗

PubMed1998

Sulfatide reduces leucocyte accumulation and reverts vascular failure in splanchnic artery occlusion shock.

Selectin-mediated leucocyte accumulation is implicated in the pathogenesis of splanchnic artery occlusion. Sulfatide is recognized by P-selectin and blocks this adhesion molecule. We investigated the effects of sulfatide in rats subjected to splanchnic artery occlusion shock. Anaesthetized rats, subjected to total occlusion of the superior mesenteric artery and the coeliac trunk for 45 min developed severe shock resulting in death within 85-90 min after the release of occlusion. Sham operated animals were used as controls. Splanchnic artery occlusion shocked rats had marked hypotension, enhanced levels of tumor necrosis factor-alpha (TNF-alpha) in serum and macrophages, leucopenia and increased ileal leucocyte accumulation, studied by the means of myeloperoxidase activity. Furthermore, aortae from shocked rats showed marked hyporeactivity to phenylephrine (1 nM-10 microM), reduced responsiveness to acetylcholine (10 nM-10 microM) and an increased staining for P-selectin in the vasculature. In vivo administration of sulfatide (10 mg/kg, i.v., 5 min after occlusion of the splanchnic arteries) increased survival rate (90%, 4 h after splanchnic artery occlusion shock), enhanced mean arterial blood pressure, reduced serum TNF-alpha (37 +/- 11 U/ml vs. 398 +/- 18 U/ml), ameliorated leucopenia and reduced ileal myeloproxidase activity (1.2 +/- 0.4 U/g tissue vs. 8.2 +/- 0.8 U/g tissue). Aortae from splanchnic artery occlusion shocked rats treated with sulfatide exhibited a greater contractile response to phenylephrine and improved responsiveness to acetylcholine. Moreover sulfatide-treated rats showed a reduced staining for P-selectin in the aorta and in the superior mesenteric artery. Finally, passive immunization with specific monoclonal antibodies raised against P-selectin significantly protected from the lethality induced by splanchnic artery occlusion shock. Our results suggest that sulfatide protects against splanchnic artery occlusion shock.

Acetylcholine↗

PubMed1997

17Beta-oestradiol reduces cardiac leukocyte accumulation in myocardial ischaemia reperfusion injury in rat.

We investigated whether oestrogens modulate the phenomenon of leukocyte accumulation during ischaemia and reperfusion of the myocardium. Anaesthetized rats were subjected to total occlusion (1 h) of the left main coronary artery followed by 1 h reperfusion. Sham myocardial ischaemia-reperfusion rats (Sham) were used as controls. Myocardial necrosis, myocardial myeloperoxidase activity, serum creatinine phosphokinase activity, serum and macrophages tumour necrosis factor (TNF-alpha) and the myocardial staining of intercellular adhesion molecule-1 (ICAM-1) were evaluated. Myocardial ischaemia plus reperfusion in untreated rats produced marked myocardial necrosis, increased serum creatinine phosphokinase activity (348 +/- 38 U/ml) and cardiac myeloperoxidase activity, a marker of polymorphonuclear leukocyte accumulation, both in the area at risk and in the necrotic area (MPO 9 +/- 1.1 mU/g tissue and 8.2 +/- 1 mU/g tissue, respectively), and induced a marked increase in the macrophage (156 +/- 14 U/ml at the end of reperfusion) and serum (344 +/- 12 U/ml, at the end of reperfusion) levels of TNF-alpha. Finally, myocardial ischaemia-reperfusion injury increased ICAM-1 staining in the myocardium. Administration of 17beta-oestradiol (5, 10 and 20 microg/kg, i.m. 5 min after induction of myocardial ischaemia-reperfusion injury), lowered myocardial necrosis and myeloperoxidase activity in the area at risk and in the necrotic area, reduced serum and macrophages TNF-alpha (20 +/- 3 U/ml and 9 +/- 3 U/ml, respectively) and decreased serum creatinine phosphokinase activity (67 +/- 3 U/ml). Oestrogen treatment also blunted the increased staining of ICAM-1 in the injured myocardium. Finally, 17beta-oestradiol added in vitro to peritoneal macrophages collected from untreated rats subjected to myocardial ischaemia-reperfusion injury, significantly reduced TNF-alpha production. Our results suggest that 17beta-oestradiol, by inhibiting TNF-alpha production, limits the deleterious ICAM-1-mediated binding of leukocytes to injured myocardium and protects against myocardial ischaemia-reperfusion injury.

Animals↗

PubMed1997

The involvement of tumour necrosis factor-alpha in the protective effects of 17 beta oestradiol in splanchnic ischaemia-reperfusion injury.

1. Tumour necrosis factor-alpha (TNF-alpha) is a cytokine that is implicated in the pathogenesis of ischaemic states and atherosclerosis. We tested the hypothesis that the vasoprotective effects of the oestrogens may be mediated in vivo by inhibition of the formation of TNF-alpha. 2. Anaesthetized rats, subjected to total occlusion of the superior mesenteric artery and the coeliac trunk for 45 min developed a severe shock state resulting in a fatal outcome within 75-90 min after the release of occlusion. Sham-operated animals were used as controls. 3. Splanchnic artery occlusion (SAO) shocked rats had a marked hypotension, enhanced levels of TNF-alpha in serum and macrophages, leukopenia and increased ileal leukocyte accumulation, studied by means of myeloperoxidase activity (MPO). Furthermore, aortae from SAO rats showed a marked hyporeactivity to phenylephrine (PE, 1 nM-10 microM), reduced responsiveness to acetylcholine (ACh, 10 nM-10 microM) and an increased staining for intercellular adhesion molecule-1 (ICAM-1). 4. In vivo administration of 17 beta oestradiol (500 micrograms kg-1, i.m., three hours before the induction of SAO) increased survival rate (100%, 4 h after SAO), enhanced mean arterial blood pressure; reduced serum TNF-alpha (25 +/- 5 u ml-1 vs 379 +/- 16 u ml-1), ameliorated leukopaenia and reduced ileal MPO (0.7 +/- 0.02 u 10(-3) g-1 tissue vs 4.2 +/- 0.4 u 10(-3) g-1 tissue). Furthermore aortae from SAO rats treated with 17 beta oestradiol exhibited a greater contractile response to phenylephrine, improved responsiveness to ACh and a blunted staining of ICAM-1. Finally 17 beta oestradiol, added in vitro to peritoneal macrophages collected from untreated SAO rats, significantly reduced TNF-alpha production. 5. Our results suggest that inhibition of TNF-alpha in vivo may explain, at least in part, the vasoprotective effects of oestrogens.

Animals↗

PubMedDate not supplied

Recombinant human granulocyte colony-stimulating factor reverts vascular dysfunction.

The aim of our study was to investigate the vascular effects of recombinant human granulocyte colony-stimulating factor (rh G-CSF) in a rat model of irreversible vascular failure. Male anesthetized rats were subjected to the clamping of the splanchnic arteries for 45 min. This surgical procedure resulted in an irreversible state of shock (splanchnic artery occlusion shock) characterized by high mortality rate (0% survival, 120 min following the release of clamps), a profound hypotension and vascular dysfunction consisting of a marked hyporeactivity to phenylephrine (PE 1 nM-10 microM) of aortic rings. Administration of recombinant human granulocyte colony-stimulating factor (20 micrograms/kg i.v. 5 min after the release of occlusion) increased survival rate (90% 4 h after the release of occlusion), blunted the profound hypotension and reverted the marked vascular dysfunction. Finally, rh G-CSF inhibited the activity of inducible nitric oxide synthase in peritoneal macrophages activated with endotoxin. Our data suggest that rh G-CSF may influence vascular function when low-flow states occur.

Acute Disease↗