Metabolic and contractile changes in ischaemic rat hearts after isoproterenol administration: effect of reperfusion.

The effect of isoproterenol and of ischaemia followed by reperfusion was studied in isolated perfused rat heart. Whereas after an interval of 5 min of ischaemia the mechanical and biochemical responses to catecholamine were drastically reduced, reperfusion for 1 min normalized the cardiac reactivity. After prolonged ischaemia and reperfusion the hormone-induced rise in cyclic AMP and activation of cyclic AMP dependent protein kinase remains reduced. It is suggested that these changes might be of importance for cardiac protection during a transient ischaemic period.