Factors influencing left ventricular function and oxygen usage in the normal and ischaemic perfused rat heart

Current disagreements regarding the choice of substrates for optimum recovery of mechanical performance in the oxygen deprived myocardium partly results from the failure to adequately distinguish between oxygen deprivation in a region of myocardium (ischaemia) and total oxygen deprivation (hypoxia). Attempting to solve this problem, the perfused isolated rat heart, contracting auxotonically, was used to examine the effects of glucose, lactate and acetate on mechanical recoverability and oxygen usage following hypoxia or ischaemia. With glucose administration to ischaemic preparations, mechanical parameters and oxygen usage had almost recovered to their initial resting values. Similar recoverability, but to a lesser extent, occurred with lactate or acetate. However in hypoxic preparations, initial recovery was shown only with glucose, while introduction of lactate or acetate resulted in continued deterioration. This study suggests that aerobic and anaerobic metabolized substrates may serve equally well in hearts suffering ischaemic injury whereas the mechanical performance of the hypoxic heart can be only maintained through energy derived anaerobically