Takafumi Ishihara

Dopaminergic Receptors in the Coronary Arteries

ABSTRACT The purpose of the present study was to analyse the mechanisms of action of dopamine on the coronary circulation. Dopamine increased coronary blood flow in anesthetized dogs. The increase was not abolished by propranolol but enhanced by phentolamine. The dopamine-induced coronary vasodilatation under alpha and beta adrenoceptor blockade was significantly attenuated by haloperidol which did not affect the coronary vasodilator action of acetylcholine, adenosine and papaverine. When treated with indomethacin after both alpha and beta blockade the dopamine-induced increase in coronary blood flow was strongly inhibited. It was considered that dopamine stimulated alpha and beta adrenoceptors, and specific receptors as well in the coronary arteries. A possible involvement of prostaglandin El in the regulation of coronary circulation was also suggested.