Abstract
Our aim was to test the hypothesis that cardioprotection achieved with ischemic preconditioning (PC) involves increased activity of p38 mitogen-activated protein kinase (MAPK) early during sustained coronary artery occlusion. Using the isolated buffer-perfused rabbit heart model of regional ischemia, we quantified p38 MAPK activity (pmol/min/mg protein: by biochemical assay) at 5 and 10 min into coronary occlusion in hearts that first received PC ischemia or no intervention (controls), and in non-ischemic shams. Control hearts exhibited significant increases in p38 MAPK activity, averaging 883+/-142 and 1135+/-179 at 5 and 10 min of occlusion, v 144+/-49 in shams (P<0.05 and P<0.01). p38 MAPK activity was not, however, augmented with PC; rather, at 5 min into occlusion, activity was attenuated, averaging 432+/-72 (P=N.S. v sham). This early, modest reduction in p38 MAPK activity may be physiologically relevant: in additional hearts subjected to 30 min of sustained coronary occlusion and 2 h of reperfusion, infarct size (by tetrazolium staining: expressed as a % of the risk region) was 54+/-5% in hearts treated with SB 203580 (confirmed in our study to inhibit p38 MAPK activity at 5 min into occlusion) v 70+/-5% in vehicle controls (P<0.05). Thus, cardioprotection achieved with ischemic preconditioning in rabbit heart does not involve augmentation of p38 MAPK activity early during sustained coronary occlusion.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have