Use of the isolated perfused heart for evaluation of cardiac toxicity.

The isolated perfused rat heart model can be used to evaluate cardiotoxicity, and is especially useful in distinguishing direct vs indirect cardiac injury. Various perfusion systems can be used to characterize the pathophysiologic as well as morphologic changes induced by drugs or chemicals of interest. The isolated perfused heart was used in the studies described herein to characterize the mechanism of allylamine cardiotoxicity. Rat hearts were perfused with Krebs-Henseleit buffer containing 10 mM allylamine and a latex balloon was inserted into the left ventricle to monitor pressure. Coronary flow in hearts perfused with 10 mM allylamine was similar to control hearts at 5, 10, and 30 min, but was reduced by 1 hr (11.5 +/- 0.6 ml/min/g wet heart weight vs 16.0 +/- 0.7, p less than 0.01). Peak left ventricular systolic pressure increased in hearts perfused with allylamine for 5 min (156 +/- 8 mm Hg vs 103 +/- 9, p less than 0.01), but by 2 hr was decreased compared to controls (89 +/- 6 vs 105 +/- 5, p less than 0.05). End diastolic pressure was markedly increased at 2 hr (58 +/- 3 vs 4 +/- 0.8, p less than 0.01). Morphologically, allylamine perfused hearts exhibited significant contraction band changes as well as numerous cells with marked swelling of the sarcoplasmic reticulum. The findings in this study suggest that allylamine produces direct myocardial damage that appears to be independent of coronary flow. These studies demonstrate that the isolated perfused rat heart model can be used to evaluate mechanisms of acute cardiotoxicity.