Postconditioning Improves Postischemic Cardiac Dysfunction Independently of Norepinephrine Overflow After Reperfusion in Rat Hearts: Comparison With Preconditioning

作者：Tawa Masashi; Fukumoto Taiki; Yamashita Naoto; Ohkita Mamoru; Ayajiki Kazuhide; Okamura Tomio; Matsumura Yasuo^*

来源：Journal of Cardiovascular Pharmacology, 2010, 55(1): 6-13.

• postconditioning
• preconditioning
• ischemia/reperfusion
• cardiac sympathetic nerve
• norepinephrine
• nitric oxide

We investigated whether the cardioprotective effect of ischemic postconditioning (postC) against ischemia/reperfusion (I/R)-induced cardiac dysfunction is associated with the negative control of I/R-enhanced norepinephrine (NE) overflow, an aggravating factor of I/R injury, in comparison with the effects induced by ischemic preconditioning (preC). According to the Langendorff technique, isolated rat hearts were subjected to 40-minute global ischemia followed by 30-minute reperfusion. PostC, consisting of three cycles of 30-second reperfusion followed by 30-second ischemia at the end of the 40-minute ischemia, improved I/R-induced cardiac dysfunction. However, the potency of this postC-induced improvement was somewhat weaker than that produced by preC, consisting of three cycles of 5-minute ischemia followed by 5-minute reperfusion before 40-minute ischemia. The preC treatment markedly Suppressed I/R-enhanced NE overflow, whereas postC had no apparent effect. A nonselective nitric oxide synthase inhibitor, N(G)-nitro-L-arginine, almost completely abolished postC-induced cardiac protection without affecting NE overflow, whereas the effect of preC on I/R-induced cardiac dysfunction and NE overflow was only partially inhibited by N(G)-nitro-L-arginine. These findings indicate that the beneficial effect of postC on I/R-induced cardiac dysfunction depends on nitric oxide and is irrelevant to NE overflow after reperfusion in contrast to the preC effect.

• 出版日期2010-1