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Biomedical subjects

R Hattori

Publications and source records attributed to R Hattori.

At least 19 recordsLinked to original sources
PubMed2004

Long time follow up of CD28- CD4+ T cells in living kidney transplant patients.

We previously reported that the CD28(-) CD4(+) T cell subpopulation was expanded in the kidney allograft patients with long graft survival, although these T cells were rarely found in patients with graft survival <5 yr. To understand the CD28(-) CD4(+) T cells in the long-term acceptance of kidney allografts, we examined functions of this population and performed a 4 yr follow up study. Peripheral blood mononuclear cells (PBMC) were obtained from 47 long-term living related kidney allograft recipients. CD28(+) CD4(+) and CD28(-) CD4(+) T cells purified by cell sorting were analyzed for expression of V(beta) repertoire. Donor-specific response was examined in mixed lymphocyte reaction (MLR). A follow up study with long-term kidney allograft patients was performed for 4 yr about the rate of CD28(-) CD4(+) T cells. Eleven patients were examined by MLRs against donors and third party. Four patients with a marked increase of CD28(-) CD4(+) T cells showed the donor-specific responses appeared to be lower when compared with third party-specific responses. Freshly sorted CD28(-) CD4(+) T cells showed a restricted V(beta) repertoire, whereas the V(beta) usage of CD28(+) CD4(+) T cells from the same patients was much diversified. Such difference in V(beta) repertoire was not evident between the two populations from healthy control. A follow up study showed the ratio of CD28(-) CD4(+) T cells appeared to be lower in patients who were suspected of chronic rejection. These unusual CD4(+) T cells might be related to the long-term acceptance of human transplant allografts.

Adult↗
PubMed2003

Laparoscopic radical nephrectomy for renal cell carcinoma.

PURPOSE: To estimate the efficacy of the laparoscopic radical nephrectomy we analyzed the clinical data of our series. PATIENTS AND METHODS: One hundred eighty five patients were enrolled in our laparoscopic radical nephrectomy program between July, 1992 and July, 2001. Of the 185 patients, 146 had small renal tumors (smaller than 5 cm in diameter) and 39 had large tumors (equal to or more than, 5 cm in diameter). Under a laparoscope the kidney, adrenal gland, and perirenal fatty tissue were dissected in an en bloc fashion. In case of taking out a small tumor, the specimen was fractionated within the sack to avoid an additional skin incision after entrapping in the laparoscopy sack in the working space. In case of a large tumor, regional lymph nodes dissection was done and the specimen was taken out intact in the sack through an enlarged incision. RESULTS: Our laparoscopic procedure was successful in 171 of the 185 cases; 14 patients required open surgery because of bleeding from an injured vessels or treatment for other injured organs. The mean operative time was 4.7 hours for both small and large tumors. Estimated blood loss was between 237 and 380 ml on average for small and large tumors, respectively. Full convalescence was achieved around 3 weeks after operation in both groups. Only one patient who had large tumor was found to have micrometastasis in 1 of 5 regional lymph nodes. Recurrences were observed in 4 cases of the small tumor group and in 2 cases of the large tumor group during 1 to 108 months of follow-up. CONCLUSION: Laparoscopic radical nephrectomy is a very useful and safe surgical procedure for renal cell carcinoma.

Carcinoma, Renal Cell↗
PubMed2003

Neuronal ceroid-lipofuscinosis and hydrocephalus in a chihuahua.

A two-year-old, female chihuahua presented with a six-month history of visual dysfunction. Computed tomography revealed dilation of the lateral ventricles in the central nervous system (CNS). The dog was tentatively diagnosed as having hydrocephalus and a month later was euthanased at the owner's request. The skull was expanded and dome-like in shape and an open fontanelle was observed on postmortem examination. Histologically, swollen neurons possessing yellowish pigment granules in the cytoplasm were observed throughout the CNS. These storage materials stained positively with periodic acid Schiff, Schmorl method for lipofuscin and oil red O for lipid, and showed autofluorescence under fluorescence microscopy. Ultrastructurally, the storage materials consisted of dense lamellar structures. This case was unique in having ceroid-lipofuscinosis in association with hydrocephalus.

Animals↗
PubMed2001

Use of marginal organs from non-heart-beating cadaveric kidney donors.

BACKGROUND: The severe shortage of cadaver donor kidneys for transplantation has prompted many centers to utilize older donor kidneys, which have been associated with lower graft survival rates. The aim of the present study was to examine the availability and feasibility of considering kidneys from donors over the age of 60. METHOD: We studied 252 cadaveric renal transplant recipients (156 males, 96 females) who received kidneys from uncontrolled non-heart-beating donors between 1987 and 1997. We performed in situ cooling with especially designed double-balloon catheters to minimize warm ischemic kidney damage. Recipients were classified according to donor age ( age 60), and we examined graft survival rates. All patients were followed for a minimum of 1 year after transplantation. RESULTS: Graft survival rates for recipients of kidneys from the older donor group at 1, 5, and 10 years after transplantation were 77%, 37%, and 30%, respectively. Corresponding values for the younger donor kidney recipients were 87%, 64%, and 47%, respectively (P=0.0011). Improved survival rates were noted when older kidneys were used for lighter weight recipients (<54 kg). No other significant factors impacted on older donor graft survival rates. CONCLUSION: Older donor kidneys are associated with poorer graft survival rates. However, kidney transplants from older donors can be quite effective in lighter weight recipients (<54 kg).

Adult↗
PubMed2001

Diastereoselective inter- and intramolecular pinacol coupling of aldehydes promoted by monomeric titanocene(II) complex Cp(2)TiPh.

A monomeric titanocene(III) derivative, Cp(2)TiPh, effectively promoted the pinacol coupling of both an aromatic aldehyde, benzaldehyde, and an aliphatic aldehyde, 3-phenylpropionaldehyde. The same reactive complex was successfully generated by a catalytic amount of a precursor, Cp(2)Ti(Ph)Cl, and its stoichiometric amount of Zn. The Cp(2)TiPh-catalyzed pinacol coupling of benzaldehyde derivatives and aliphatic aldehydes afforded the corresponding 1,2-diols in high yields with moderate to good threo-selectivity. On the other hand, Cp(2)TiPh-catalyzed pinacol cyclization of dials gave cyclic 1,2-diols with excellent diastereoselectivity. The extension of this protocol to chiral dials demonstrated that the phenyltitanium complex catalytically transmitted an axial chirality or a central chirality of the starting dials to the central chirality of the resultant 1,2-diols.

Journal Article↗
PubMed2001

Role of STAT3 in ischemic preconditioning.

We recently demonstrated that ischemic preconditioning (IPC) induced by cyclic episodes of short durations of ischemia and reperfusion potentiates a signal transduction cascade involving protein tyrosine kinases and MAP kinases. A rapid activation of janus kinase (JAK) and several signal transducers and activators of the transcription (STATs) including STAT3, STAT5A and STAT6 has been shown to occur during myocardial ischemia and reperfusion. This study sought to examine if JAK/STAT signaling pathway play any role in classical early phase of IPC. Isolated working rat hearts were perfused for 15 min with KHB buffer in the absence or presence of a JAK kinase inhibitor tyrphostin AG490 (5 microm) followed by IPC, 30 min global ischemia and 2 h of reperfusion. The results demonstrated extensive phosphorylation of JAK2 and STAT3 in the IPC hearts which was almost completely abolished by an inhibitor of JAK2, AG490. IPC displayed cardioprotection as evidenced by improved post-ischemic contractile recovery, decreased myocardial infarct size and reduced number of apoptotic cardiomyocytes. AG490 blocked IPC-mediated cardioprotection by altering the IPC-mediated survival signal into death signal. Thus, IPC-induced upregulation of antiapoptotic gene bcl-2 and downregulation of pro-apoptotic gene bax are decreased and increased, respectively, in the AG490 treated hearts. The results suggest that early phase of IPC potentiates JAK/STAT signaling by activating STAT3 which transmits a survival signal to the myocardium.

Animals↗
PubMed2001

Experimental study of pulmonary artery infusion with cisplatin in a solitary pulmonary tumor model using a rat colorectal adenocarcinoma cell line.

OBJECTIVES: We assessed a tumor model prepared by open lung injection to study metastatic lung tumors, and evaluated the efficacy of pulmonary artery infusion. METHODS: Subjects were 30 male F344 rats. In experiment 1, we evaluated chemosensitivity of a rat colorectal adenocarcinoma cell line (RCN-9) using a colorimetric [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. In experiment 2, we injected RCN-9 cells into the left lung on day 0; on day 10, we measured tumor tissue blood flow before and after pulmonary arterial occlusion. In experiment 3, we injected RCN-9 cells into the left lung and conducted no further procedures in controls. The pulmonary artery infusion group underwent pulmonary artery infusion with 0.1 mg of cisplatin on day 3 and the sham group injection with saline solution alone. On day 10, rats were sacrificed and maximum tumor cross-section measured. RESULTS: In experiment 1, the drug concentration required to inhibit cell growth 50% was 2.45 x 10(-6) M. In experiment 2, tumor tissue blood flow decreased significantly after arterial occlusion (p = 0.003). In experiment 3, the maximum tumor cross-section in the pulmonary artery infusion group was significantly smaller than in shams (p = 0.0027) and controls (p = 0.0019). CONCLUSIONS: The pulmonary artery supplies tumors with blood, so this model appears useful in studying metastatic lung tumors, whose size was reduced significantly by pulmonary artery infusion with cisplatin. Pulmonary artery infusion is thus a promising modality in metastatic lung tumor treatment.

Adenocarcinoma↗
PubMed2001

Characterization of CD28(-)CD4(+) T cells in living kidney transplant patients with long-term allograft acceptance.

CD28(-)CD4(+) T-cell subpopulation is expanded in kidney allograft patients with long graft survival. To seek for the roles of CD28(-)CD4(+) T cells in the long-term acceptance of kidney allografts, we characterized this population by analyzing cell surface molecules, TCR V(beta) repertoire, mixed lymphocyte reaction (MLR), and cytokine production. The number of CD28(-)CD4(+) T cells increased correlatively with time after transplantation in this group of patients. The CD28(-)CD4(+) T cells did not express detectable levels of CD25, CD69, V(alpha)24, or CTLA-4 but expressed heterogeneous amounts of CD45 RA on the surface. Freshly sorted CD28(-)CD4(+) T cells revealed a restricted V(beta) repertoire, whereas the V(beta) usage of CD28(+)CD4(+) T cells from the same patients was much diversified. Expression levels of TGF-beta and IFNgamma gene were significantly higher in the CD28(-) CD4(+) T cells than in the CD28(+)CD4(+) T cells from the kidney allograft patients. These findings suggest that an oligoclonal CD28(-) CD4(+) T-cell population is continuously activated in patients with long allograft survival, which may be linked with the long-term acceptance.

Adult↗
PubMed2001

Protein kinase C isoform-dependent myocardial protection by ischemic preconditioning and potassium cardioplegia.

OBJECTIVE: Ischemic preconditioning combined with potassium cardioplegia does not always confer additive myocardial protection. This study tested the hypothesis that the efficacy of ischemic preconditioning under potassium cardioplegia is dependent on protein kinase C isoform. METHODS: Isolated and crystalloid-perfused rat hearts underwent 5 cycles of 1 minute of ischemia and 5 minutes of reperfusion (low-grade ischemic preconditioning) or 3 cycles of 5 minutes of ischemia and 5 minutes of reperfusion (high-grade ischemic preconditioning) or time-matched continuous perfusion. These hearts received a further 5 minutes of infusion of normal buffer or oxygenated potassium cardioplegic solution. The isoform nonselective protein kinase C inhibitor chelerythrine (5 micromol/L) was administered throughout the preischemic period. All hearts underwent 35 minutes of normothermic global ischemia followed by 30 minutes of reperfusion. Isovolumic left ventricular function and creatine kinase release were measured as the end points of myocardial protection. Distribution of protein kinase C alpha, delta, and epsilon in the cytosol and the membrane fractions were analyzed by Western blotting and quantified by a densitometric assay. RESULTS: Low-grade ischemic preconditioning was almost as beneficial as potassium cardioplegia in improving functional recovery; left ventricular developed pressure 30 minutes after reperfusion was 70 +/- 15 mm Hg (P <.01) in low-grade ischemic preconditioning and 77 +/- 14 mm Hg (P <.001) in potassium cardioplegia compared with values found in unprotected control hearts (39 +/- 12 mm Hg). Creatine kinase release during reperfusion was also equally inhibited by low-grade ischemic preconditioning (18.2 +/- 10.6 IU/g dry weight, P <.05) and potassium cardioplegia (17.6 +/- 6.7 IU/g, P <.01) compared with control values. However, low-grade ischemic preconditioning in combination with potassium cardioplegia conferred no significant additional myocardial protection; left ventricular developed pressure was 80 +/- 17 mm Hg, and creatine kinase release was 14.8 +/- 11.0 IU/g. In contrast, high-grade ischemic preconditioning with potassium cardioplegia conferred better myocardial protection than potassium cardioplegia alone; left ventricular developed pressure was 121 +/- 16 mm Hg (P <.001), and creatine kinase release was 8.3 +/- 5.8 IU/g (P <.05). Chelerythrine itself had no significant effect on functional recovery and creatine kinase release in the control hearts, but it did inhibit the salutary effects not only of low-grade and high-grade ischemic preconditioning but also those of potassium cardioplegia. Low-grade ischemic preconditioning and potassium cardioplegia enhanced translocation of protein kinase C alpha to the membrane, whereas high-grade ischemic preconditioning also enhanced translocation of protein kinase C delta and epsilon. Chelerythrine inhibited translocation of all 3 protein kinase C isoforms. CONCLUSIONS: These results suggest that myocardial protection by low-grade ischemic preconditioning and potassium cardioplegia are mediated through enhanced translocation of protein kinase C alpha to the membrane. It is therefore suggested that activation of the novel protein kinase C isoforms is necessary to potentiate myocardial protection under potassium cardioplegia.

Animals↗
PubMed2001

Insulin-like growth factor 1 prevents neuronal cell death and paraplegia in the rabbit model of spinal cord ischemia.

OBJECTIVE: Insulin-like growth factor 1 has been shown to be cytoprotective against ischemia-reperfusion injury in various organs. However, spinal cord protection by insulin-like growth factor 1 has not been tested. We have therefore examined the effect of insulin-like growth factor 1 on neuronal cell death and motor function after spinal cord ischemia. METHODS: Japanese white rabbits were subjected to spinal cord ischemia by clamping the abdominal aorta for 15 minutes. Insulin-like growth factor 1 (0.3 mg/kg) at a dose equipotent to insulin (0.3 IU/kg) in lowering blood glucose level or the control (phosphate-buffered saline solution as a vehicle) was administered intravenously 30 minutes before the aortic clamp. RESULTS: Hind-limb motor function had recovered normally 48 hours after the operation in all the rabbits (n = 8) treated with insulin-like growth factor 1. In contrast, all the control-treated (n = 8) and all but one of the insulin-treated (n = 6) rabbits had deteriorated to paraplegia by 48 hours after the operation. Histopathologic sections in the involved spinal cord segment showed that a significantly (P <.0001) greater number of motor neuron cells were preserved in the rabbits treated with insulin-like growth factor 1 (17.9 +/- 4.8 per section) than in those treated with the control (8.0 +/- 2.1). Although insulin was equipotent to insulin-like growth factor 1 in preserving the number of motor neuron cells (18.5 +/- 2.7), the percentage of motor neuron cells positive for terminal deoxynucleotidyltransferase-mediated deoxyuridine triphosphate-biotin nick-end labeling were significantly (P <.01) smaller in the rabbits treated with insulin-like growth factor 1 (6.0 +/- 4.6) compared with those treated with the control (54.6 +/- 33.8) and insulin (26.2 +/- 11.7). Immunohistochemical studies revealed that insulin-like growth factor 1 increased expression of the antiapoptotic Bcl-xL protein and inhibited expression of the proapoptotic Bax protein in motor neuron cells 24 and 48 hours after the operation. In contrast, expression of only Bax was increased after the operation in other groups of rabbits subjected to spinal cord ischemia. CONCLUSIONS: These results suggest that insulin-like growth factor 1, but not insulin with a conventional dose, protects motor neuron cells from ischemic spinal cord injury associated with differential regulation of Bcl-xL and Bax protein.

Animals↗
PubMed2001

An essential role of the antioxidant gene Bcl-2 in myocardial adaptation to ischemia: an insight with antisense Bcl-2 therapy.

Reperfusion of ischemic myocardium results in apoptotic cell death, which can be blocked by adapting the heart to ischemic stress induced by cyclic episodes of brief periods of ischemia and reperfusion. In concert, the antiapoptotic gene bcl-2 is decreased by ischemia/reperfusion, but increased in the ischemically adapted myocardium. To examine if bcl-2 plays a crucial role in cardioprotection, adaptive cardioprotection was further examined in the hearts treated with antisense bcl-2 oligodeoxynucleotides (ODN). Isolated Langendorff-perfused rat hearts were divided into three groups: control (perfused with Krebs-Henseleit bicarbonate buffer for 210 min); 30-min ischemia followed by 2-h reperfusion; ischemic adaptation followed by 30-min ischemia and 2-h reperfusion. The last (adapted heart) group was subdivided into another two groups: one was transfected 48 h earlier with antisense bcl-2 ODN, whereas the other group was transfected with sense bcl-2 ODN. Cardioprotection was examined by determining cardiomyocyte death due to necrosis and apoptosis. Antisense gene therapy almost completely abolished bcl-2 protein expression in the hearts. Bcl-2 mRNA was down-regulated in the ischemic/reperfused heart, but up-regulated in the adapted myocardium. Adapted myocardium showed decreased infarct size and reduced number of apoptotic cardiomyocytes. Ischemia/reperfusion resulted in increased oxidative stress as evidenced by increased malonaldehyde formation. Adapted myocardium had a reduced amount of malonaldehyde. Antisense bcl-2 ODN completely abolished the cardioprotective effects of adaptation by eliminating the antideath signal of bcl-2. In concert, reduced oxidative stress in the adapted myocardium no longer persisted. The results suggest an antioxidant role of bcl-2 that appeared to be essential for the cardioprotection achieved by ischemic adaptation.

Adaptation, Physiological↗
PubMed2001

Dual involvement of coenzyme Q10 in redox signaling and inhibition of death signaling in the rat heart mitochondria.

Coenzyme Q10 (CoQ) has long been utilized as a cardioprotective agent in various heart diseases. One of the most important mechanisms by which CoQ exerts cardioprotection is aerobic ATP production as a mobile electron carrier in the mitochondrial electron transfer chain. The ability of CoQ to afford myocardial protection is also attributed to its antioxidant property. However, CoQ may also act as a pro-oxidant through the generation of reactive oxygen species. Although excess oxidative stress is known to induce death signaling via cytochrome c release from mitochondria, it is now apparent that a brief exposure to oxidative stress stimulates redox signaling for acquisition of tolerance to oxidative stress. Therefore, we have investigated dual involvement of CoQ in redox signaling generation through enhanced production of reactive oxygen species and death signaling inhibition through antioxidation. Mitochondria were isolated from the rat heart and incubated with CoQ (10 or 100 microM) or its vehicle HCO 60 for 1 h. H2O2 and cytochrome c release from respiring mitochondria were increased by antimycin A (2 microM), an inhibitor of complex III respiratory chain, or by high Ca2+ (10 microM). This enhanced release of H2O2 was associated with an increase in lipid peroxidation as measured with 4-hydroxy-2-nonenal-modified proteins and with large amplitude swelling of mitochondria. CoQ potentiated H2O2 release from antimycin A- or high Ca(2+)-treated mitochondria, but was capable of inhibiting lipid peroxidation and large amplitude swelling, and attenuated cytochrome c release from the mitochondria. In addition, CoQ increased ATP synthesis by mitochondria. These results suggest that CoQ plays dual roles in mitochondrial generation of intracellular signaling. CoQ acts as a pro-oxidant that participates in redox signaling. CoQ also acts as an antioxidant that inhibits permeability transition and cytochrome c release, and increases ATP synthesis, thereby attenuating death signaling toward apoptosis and necrosis.

Adenosine Triphosphate↗
PubMed2001

The long-term outcome of laparoscopic radical nephrectomy for small renal cell carcinoma.

PURPOSE: To evaluate the efficacy of laparoscopic radical nephrectomy in patients with small renal cell carcinoma, we analyzed the long-term results in those treated with laparoscopy and those undergoing open surgery. MATERIALS AND METHODS: A total of 149 patients with tumors less than 5 cm. in diameter enrolled in a radical nephrectomy program between January 1992 and March 2000. Of these patients 103 were treated laparoscopically and the remaining 46 underwent open surgery. Patient followup was until June 30, 2000. RESULTS: Laparoscopy followup was from 3 to 95 months (median 29). A total of 100 patients survived, 2 died without any recurrent disease in months 34 and 45, respectively, and 1 dropped out in postoperative month 3. Seeding of the port sites did not develop in any of the patients. There were 3 patients who had metastatic disease in months 3, 19 and 61, respectively, and 1 had local recurrence in postoperative month 43. The 5-year disease-free and patient survival rates were 95.1%, and 95.0%, respectively. Except for 2 patients who dropped out in months 10 and 16, respectively, 44 who underwent open surgery were followed from 11 to 101 months (median). Of the 44 patients 41 survived without any recurrent disease, 1 also survived with metastasis and 2 died of metastatic disease in months 7 and 11, respectively. The 5-year disease-free and patient survival rates were 89.7% and 95.6%, respectively. CONCLUSIONS: Laparoscopic radical nephrectomy can be an alternative to open nephrectomy in patients with localized small renal cell carcinoma.

Adult↗
PubMed2001

IGF-I differentially regulates Bcl-xL and Bax and confers myocardial protection in the rat heart.

Bcl-2 family proteins play a crucial role in the cytoprotective action of insulin-like growth factor-I (IGF-I) by regulating cell death signaling at the mitochondrial level. The present study examined the effect of IGF-I on the expression of Bcl-2 family proteins in the rat heart mitochondria in relation to myocardial protection against ischemia-reperfusion injury. Systemic IGF-I (1 mg) treatment in the rat increased Bcl-xL and attenuated Bax 12-24 h later in the heart mitochondria fraction. Permeability transition and cytochrome c release occurred in a Ca(2+) concentration-dependent manner in the vehicle-treated mitochondria. This was significantly inhibited by the IGF-I-pretreatment. Moreover, ATP synthesis was significantly greater in the IGF-I-pretreated mitochondria. IGF-I pretreatment 24 h before 25 min of global ischemia in the isolated rat heart model significantly improved recovery of isovolumic left ventricular function and inhibited creatine kinase release during reperfusion. This was associated with a significantly less number of terminal transferase labeling-positive myocytes and nonmyocytes 2 h after reperfusion. These results suggest that IGF-1 differentially regulates Bcl-xL and Bax in heart mitochondria, which may be causally related to myocardial protection against ischemia-reperfusion injury.

Adenosine Triphosphate↗
PubMed2001

NHE and ICAM-1 expression in hypoxic/reoxygenated coronary microvascular endothelial cells.

Although Na+/H+ exchange (NHE) has been implicated in myocardial reperfusion injury, participation of coronary microvascular endothelial cells (CMECs) in this pathogenesis has been poorly understood. NHE-induced intracellular Ca2+ concentration ([Ca2+]i) overload in CMECs may increase the synthesis of intercellular adhesion molecules (ICAM), which is potentially involved in myocardial reperfusion injury. The present study tested the hypothesis that NHE plays a crucial role in [Ca2+]i overload and ICAM-1 synthesis in CMECs. Primary cultures of CMECs isolated from adult rat hearts were subjected to acidic hypoxia for 30 min followed by reoxygenation. Two structurally distinct NHE inhibitors, cariporide and 5-(N-N-dimethyl)-amiloride (DMA), had no significant effect on the acidic hypoxia-induced decrease in intracellular pH (pH(i)) of CMECs but significantly retarded pH(i) recovery after reoxygenation. These NHE inhibitors abolished the hypoxia- and reoxygenation-induced increase in [Ca2+]i. Expression of ICAM-1 mRNA was markedly increased in the vehicle-treated CMECs 3 h after reoxygenation, and this was significantly inhibited by treatment with cariporide, DMA, or Ca2+-free buffer. In addition, enhanced ICAM-I protein expression on the cell surface of CMECs 8 h after reoxygenation was attenuated by treatment with cariporide, DMA, or Ca2+-free buffer. These results suggest that NHE plays a crucial role in the rise of [Ca2+]i and ICAM-1 expression during acidic hypoxia/reoxygenation in CMECs. We propose that inhibition of ICAM-1 expression in CMECs may represent a novel mechanism of action of NHE inhibitors against ischemia-reperfusion injury.

Amiloride↗
PubMed2001

Src tyrosine kinase is the trigger but not the mediator of ischemic preconditioning.

The signal cascade that triggers and mediates ischemic preconditioning (IPC) remains unclear. The present study investigated the role of the Src family of tyrosine kinases in IPC. Isolated and buffer-perfused rat hearts underwent IPC with three cycles of 5-min ischemia and 5-min reperfusion, followed by 30-min ischemia and 120-min reperfusion. The Src tyrosine kinase family-selective inhibitor PP1 was administered between 45 and 30 min before ischemia (early PP1 treatment) or for 15 min before IPC [early PP1-preconditioning (PC) treatment]. PP1 was also administered for 5 min before the sustained ischemia (late PP1 treatment) or after IPC (late PP1-PC treatment). Src kinase was activated after 30 min of ischemia in both the membrane and cytosolic fractions. Src kinase was also activated by IPC but was attenuated after the sustained ischemia. Early and late PP1 treatment inhibited Src activation after the sustained ischemia and reduced infarct size. Early PP1-PC inhibited Src activation after IPC but not after the sustained ischemia and blocked cardioprotection afforded by IPC. Late PP1-PC treatment abrogated IPC-induced activation of Src and protein kinase C (PKC)-epsilon in the membrane but not in the cytosolic fraction. This treatment modality abrogated Src activation after the sustained ischemia and failed to block cardioprotection afforded by IPC. These results suggest that Src kinase activation mediates ischemic injury but triggers IPC in the position either upstream of or parallel to membrane-associated PKC-epsilon.

Animals↗