Halothane inhibits calcium accumulation following myocardial ischemia and calcium paradox in guinea pig hearts.

This study was performed to test the hypothesis that halothane inhibits calcium accumulation associated with myocardial ischemia and calcium paradox. Using a Langendorff preparation in isolated guinea pig hearts, tissue 45Ca was measured after 40 and 60 min of loading with 45Ca, followed by 20 min of washout period. Myocardial ischemia was produced by a 30-min occlusion of the left anterior descending coronary artery (LAD). LAD occlusion caused an increase in 45Ca content in the anterior left ventricular muscle (ischemic area) of 215% compared to that of the posterior left ventricular muscle (normal myocardium). The increase in 45Ca content in the ischemic area was significantly less (P less than 0.05) in the presence of halothane (1%) compared to the non-halothane group. Halothane did not significantly alter 45Ca content in the non-ischemic myocardium. Myocardial injury associated with calcium paradox, which was produced by a 10-min perfusion of the heart with calcium-free Krebs solution followed by normal calcium repletion, caused a significant increase (P less than 0.05) in the 45Ca content compared to control. Addition of halothane (1%) significantly depressed (P less than 0.05) the increase in 45Ca content caused by calcium paradox. It is suggested that halothane might inhibit calcium accumulation associated with myocardial ischemia and calcium paradox under certain experimental situations. The inhibitory effect of halothane on calcium accumulation may be beneficial for the ischemic heart during halothane anesthesia.