Acute hemodynamic effects of an alpha- and beta-receptor blocking agent (AH 5158) on the systemic and pulmonary circulation at rest and during exercise in hypertensive patients.

The acute hemodynamic effects of 50 mg. of the alpha- and beta-receptor blocking agent AH 5158, administered intravenously, on the systemic and pulmonary circulation were studied in 13 hypertensive patients at rest in the supine and erect positions, and during exercise, with right heart and brachial artery catheterization. AH 5158 induced a significant fall of systemic blooc pressures under all conditions, whereas the pulmonary systolic and mean pressures were lower at rest and unaltered during exercise. The left ventricular filling pressure largely remained unchanged. Blood pressure was lowered predominantly by a reduction in systemic vascular resistance together with a reduction in cardiac output. These effects were particularly pronounced in the erect position and during exercise. Cardiac output was lowered solely by the reduction of heart rate; stroke volume was unchanged or even increased. The arterial-mixed venous oxygen difference increased in the erect position and during exercise. The pattern of AH 5158-induced hemodynamic adaptation comprising a reduction of both vascular resistance and cardiac output, without evidence of significant negative inotropic action, offers a novel basis for treating hypertension with a single drug. Its pharmacological and hemodynamic profile suggests considerable potential in the treatment of hypertensive patients.