Infarct size-limiting effect of calcium preconditioning in rabbit hearts.
Recent studies demonstrated that brief period of Ca2+ depletion and repletion (Ca2+ preconditioning, CPC) has strong protective effects against ischemia in a rat heart. CPC and classic preconditioning (IPC) were compared in relation with infarct size and protein kinase C (PKC) isozymes. Isolated Langendorff-perfused rabbit hearts were subjected to 45-min ischemia (Isc) followed by 120-min reperfusion (R) with or without IPC, induced by 5-min Isc and 10-min R. In the CPC hearts, 5-min Ca2+ depletion and 10-min repletion (CPC) were given before 45-min Isc, with or without concurrent PKC inhibition (calphostin C, 200 nmol/L). IPC enhanced recovery of LV function, while CPC did not. Infarct size was significantly reduced by both CPC and IPC (p < 0.05 vs. ischemic control). Membrane PKC was significantly increased from 2.53 +/- 0.07 (baseline, nmol/g tissue) to 3.11+/-0.07, 3.34 +/- 0.11, 3.15 +/- 0.09, and 3.06 +/- 0.08 by IPC, IPC and 45-min Isc, CPC and 45-min Isc, respectively (p < 0.01). Immunoblots of membrane PKC were increased by IPC, IPC and 45-min Isc, and CPC. These effects were abolished by PKC inhibition. Thus, activation of PKC may have trigger role in the mechanism of cardioprotective effect by CPC.
Kim
Ho-dirk
HD
Department of Anatomy and Cell Biology, Sungkyunkwan University School of Medicine, Suwon, Korea. hdkim@med.skku.ac.kr
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002316:Cardiotonic Agents / Q000494:pharmacology*; D066298:In Vitro Techniques; D019157:Ischemic Preconditioning, Myocardial; D007527:Isoenzymes / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008297:Male; D009203:Myocardial Infarction / Q000473:pathology*; D009206:Myocardium / Q000201:enzymology / Q000473:pathology; D011493:Protein Kinase C / Q000378:metabolism; D051744:Protein Kinase C-epsilon; D011817:Rabbits
D002316:Cardiotonic Agents; D007527:Isoenzymes; D007770:L-Lactate Dehydrogenase; D011493:Protein Kinase C; D051744:Protein Kinase C-epsilon; D002118:Calcium