Factors affecting myocardial storage and release of catecholamines.

IN A PREVIOUS publication from this laboratory, it was shown that the addition of Dopa to the perfusion fluid of the heartlung preparation elevated the catecholamine concentration in the isolated heart without preventing the decline in cardiac work. Previous investigators had already demonstrated that various organs, including the heart, contained catecholamines." The concentration of these substances in heart muscle could be increased by previous administration of Dopa, a precursor of dopamine, norepinephrine, and epinephrine.' 10 Carlsson and Hillarp reported in 1956 that reserpine induced the complete liberation of catecholamines from the adrenal medulla of rabbits, and in the same year Bertler, Carlsson, and Rosengren described a similar effect on the heart. This communication will report on the storage and release of catecholamines in and from heart muscle. The influence of Dopa, iproniazid, reserpine, or nicotine will be described, as well as the effect of ventricular tachycardia and fibrillation. Methods Dogs anesthetized with sodium pentobarbital (30 nig. per Kg.) were used. Iproniazid* was injected 24 hours prior to these experiments (50 mg. per Kg. intraporitoneally). Dopat (40 mg.