© 1999 by European Society of Cardiology
Copyright © 1999, European Society of Cardiology
Ischemic preconditioning limits infarct size following regional ischemia–reperfusion in in situ mouse hearts
aDepartment of Anesthesiology, Oregon Health Sciences University, Portland, OR, USA
bResearch and Anesthesiology Services, P-8-ANES VA Medical Center 3710 SW US Veterans Hospital Road, Portland, OR 97201 USA
vanwinkd{at}ohsu.edu
* Corresponding author. Tel.: +1-503-220-8262, ex 57404; fax: +1-503-721-7956
Objective: Ischemic preconditioning has been demonstrated in a wide variety of animals, from dogs to rats. Experimentally-induced murine myocardial ischemia–reperfusion has been described, but ischemic preconditioning has not been reported in mouse hearts. To test the hypothesis that mouse hearts exhibit preconditioning-induced protection, experiments were conducted in anesthetized open chest mice subjected to regional myocardial ischemia–reperfusion. Methods: Following barbiturate anesthesia the FVB and C57BL/6J mice underwent a tracheostomy and were mechanically ventilated. The heart was exposed via a left thoracotomy performed with the aid of a dissecting microscope. A 7-0 silk suture on a curved taper needle was passed under the proximal left anterior descending coronary artery to form a snare. Mice were then randomly assigned to receive either no preconditioning or preconditioning. All mice were subjected to 60 min regional myocardial ischemia followed by 2.5 h of reperfusion. Ischemic preconditioning (IP) was induced with two (FVB mice) or three (C57BL/6J mice) cycles of 5 min coronary occlusion and 5 min reperfusion. Control animals did not receive preconditioning ischemia. Area-at-risk was assessed with fluorescent particles. Infarct size was assessed with triphenyl tetrazolium chloride, and is expressed below as a percentage of the area-at-risk. Results: In FVB mice preconditioning reduced infarct size 49%, from 36.7±4.5% to 18.9±2.8% (P<0.05). In C57BL/6J mice preconditioning reduced infarct size by 66%, from 56.4±8.3% to 18.9±4.2% (P<0.05). Conclusion: From these data we conclude that the infarct limiting effect of ischemic preconditioning is demonstrable in murine hearts.
KEYWORDS Ischemic preconditioning; Myocardial infarct size; Mice