Effects of postconditioning of adenosine and acetylcholine on the ischemic isolated rat ventricular myocytes

In this study, protective effects of adenosine and acetylcholine-induced postconditioning were investigated on the contractile function of the ischemic isolated rat ventricular myocytes. A video-based edge-detection system was used to monitor single ventricular myocytes contraction. Adenosine and acetylcholine were administrated for 6 min before ischemia as preconditioning, or 15 min after ischemia as postconditioning. Adenosine and acetylcholine receptor antagonists and mitoK(ATP) inhibitor were used to analyze pathways underlying the effects on postconditioning. Results: (1) The peak shortening of ischemic heart cells was improved by both adenosine and acetylcholine during preconditioning (84.72 +/- 5.34% and 68.61 +/- 8.10% vs. control: 8.43 +/- 5.35% of the pre-ischemia value), as well as postconditioning (76.47 +/- 7.87% and 57.48 +/- 6.97% vs. control: 8.43 +/- 5.35% of the pre-ischemia value) and the effects of preconditioning and postconditioning were comparable. More datum in the normal text. (2) Observed effects of adenosine and acetylcholine postconditioning were missing in the presence of adenosine A, receptor and muscarinic M-2 receptor antagonists, respectively. (3) Adenosine and acetylcholine-induced postconditioning was also blocked by mitoK(ATP) antagonist. These results suggest that both adenosine and acetylcholine protect the contractile function of ischemic heart cells to a similar extent during preconditioning and postconditioning. The postconditioning of adenosine and acetylcholine is relative to the adenosine A(1) and muscarinic M-2 receptors, respectively. MitoK(ATP) is implicated in the postconditioning of both acetylcholine and adenosine. (c) 2006 Elsevier B.V. All rights reserved.