Sevoflurane-induced Preconditioning Impact of Protocol and Aprotinin Administration on Infarct Size and Endothelial Nitric-Oxide Synthase Phosphorylation in the Rat Heart In Vivo

Background Sevoflurane induces preconditioning (SevoPC) 1 he effect of aprotinin and the involvement of endothelial nitric-oxide synthase (NOS) on SevoPC are unknown We investigated (1) whether SevoPC is strengthened by multiple preconditioning cycles (2) whether SevoPC is blocked by aprotinin, and (3) whether endothelial NOS plays a crucial role in SevoPC Methods Anesthetized male Wistar rats were randomized to 15 groups (each n = 6) and underwent 25-min regional myocardial ischemia and 2-h reperfusion Controls were not treated further Preconditioning groups inhaled 1 minimum alveolar concentration of sevoflurane for 5 min (SEVO-I), twice for 5 min each (SEVO-II), three times for 5 min each (SEVO-III), or six times for 5 min each (SEVO-VI) Aprotinin was administered with and without sevoflurane Involvement of endothelial NOS was determined with the nonspecific NOS blocker w-nitro-I-arginine-methyl-ester, the specific neuronal NOS blocker 7-nitroindazole, and the specific inducible NOS blocker aminoguanidine Results SevoPC reduced infarct size in all protocols (SEVO-I, 42 +/- 6% SEVO-II 33 +/- 4%, SEVO-III, 11 +/- 5% SEVO-VI, 16 4%, all P <0 001 vs control, 67 +/- 3%) and was least after three and six cycles of sevoflurane (P <0 001 vs SEVO-II and -I, respectively) Aprotinin alone had no effect on infarct size but blocked SevoPC N-nitro-L-arginine-methyl-ester abolished SevoPC (67 +/- 4%, P <0 05 vs SEVO-III) Aminoguanidine and 7-nitroindazole blocked SevoPC only partially (25 +/- 6 and 31 +/- 6%, respectively, P <0 05 vs SEVO-III and control) SevoPC induced endothelial NOS phosphorylation, which was abrogated by apron n in Conclusion SevoPC is strengthened by multiple preconditioning cycles, and phosphorylation of endothelial NOS is a crucial step in mediating SevoPC These effects are abolished by aprotinin