DELETERIOUS EFFECTS OF ENDOGENOUS CATECHOLAMINES ON HYPOXIC MYOCARDIAL-CELLS FOLLOWING RE-OXYGENATION

The ability of endogenous myocardial catecholamines to modify biochemical alterations during conditions of severe myocardial hypoxia and subsequent reoxygenation was studied in isolated, Langendorff-perfused, potassium-arrested, rat heart preparations. Hearts depleted of endogenous catecholamines (induced by reserpine pretreatment) exhibited higher levels of ATP, creatine phosphate and glycogen and a lesser amount of lactate dehydrogenase release following 100 min of hypoxia (95% N2: 5% CO2). The large amount of myocardial lactate dehydrogenase release normally present during reoxygenation of the hypoxic heart (oxygen paradox) was abolished by reserpine pretreatment. These biochemical changes in reserpinized hearts reflect a diminution of myocardial cell damage. Glucagon administration reversed all the beneficial effects of catecholamine depletion in conditions of both severe hypoxia and reoxygenation. It is concluded that endogenous myocardial catecholamines exert harmful effects on the evolution of hypoxic myocardial cell damage in the rat. © 1979.