Cardioprotection in pigs by exogenous norepinephrine but not by cerebral ischemia-induced release of endogenous norepinephrine

BACKGROUND AND PURPOSE: Endogenous norepinephrine release induced by cerebral ischemia may lead to small areas of necrosis in normal hearts. Conversely, norepinephrine may be one of the mediators that limit myocardial infarct size by ischemic preconditioning. Because brief ischemia in kidneys or skeletal muscle limits infarct size produced by coronary artery occlusion, we investigated whether cardiac norepinephrine release during transient cerebral ischemia also elicits remote myocardial preconditioning. METHODS: Forty-one crossbred pigs of either sex were assigned to 1 of 7 experimental groups, of which in 6 groups myocardial infarct size was determined after a 60-minute coronary occlusion and 12