[The effect of captopril on the coronary circulation in a clinical and experimental study]

Taking into account the well-known angiotensin II-induced coronary constriction, in a first series of experiments the effects of captopril were studied upon the rabbit, guinea pig and rat coronary circulation during perfusion with oxygenated Krebs-Henseleit solution at 37 degrees C under constant pressure and variable flow according to the Langendorf technique. The inhibition of angiotensin I to angiotensin II conversion enzyme with captopril (5-500 microgr./ml) resulted in a coronary dose dependent dilation as a consequence of a reduction in the basal coronary tonus. Testing the coronary distensibility by using pressure and flow variations revealed a significantly increased distensibility when the conversion enzyme was specifically blocked with captopril. The anginal threshold of the atrial electrostimulation was increased after captopril (25-50 mg i.v.) in 15 out of 18 patients with coronary insufficiency by a mean value of 17%, white the systolic dynamics was significantly better. The obtained results bring new arguments in favour of the intrinsic renin-angiotensin system participation in maintaining the basal vascular tonus and of the increased coronary distensibility in the presence of captopril as an inhibitor of the local synthesis of the vasoconstrictor angiotensin II.