Normothermic ischaemic cardiac arrest of isolated working rat heart: effects of reserpine and propranolol on functional, metabolic and morphological recovery.

The ability to preserve myocardial structural and functional integrity during extended periods of total ischaemia has practical clinical significance. The role of endogenous catecholamines in the onset of irreversible damage in global ischaemia of the isolated rat heart was assessed by beta-blockade or catecholamine depletion. The effects of propranolol and reserpine pretreatment on myocardial ultrastructure, function and metabolism were studied during normothermic ischaemic arrest (NICA) and reperfusion of the isolated working rat heart. beta-Blockade as well as catecholamine depletion resulted in an increase in the percentage of totally ischaemic hearts which recovered mechanically upon reperfusion. In these studies mechanical recovery during reperfusion was associated with reversal of ultrastructural ischaemic alterations, but without an improvement in mitochondrial function. These findings support the concept that failure of mitochondria to recover functionally upon reperfusion is not the cause of either irreversible mechanical failure or ultrastructural damage of the ischaemic myocardium.