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 < 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 < 0.05) in the ⁴⁵Ca content compared to control. Addition of halothane (1%) significantly depressed (P < 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 ischemia heart during halothane anesthesia.