Systemic and renal vasodilation after beta-adrenoceptor blockade with pindolol: a hemodynamic study on the onset and maintenance of its antihypertensive effect.

Pindolol, a beta blocker with considerable partial agonist activity (PAA), was studied in 10 hypertensive subjects. The maximal fall in mean arterial pressure (MAP) was seen 3 to 4 hours after oral dosing with 10 mg of pindolol (-15 +/- 3%, mean +/- SEM). This was caused by a reduction in total peripheral resistance (TPR), which amounted to 25 +/- 4% after 24 hours. Cardiac output increased by 16 +/- 5%. Cardiac filling pressures and pulmonary artery pressure did not change. Increasing the dose of pindolol, from 5 mg twice a day to 15 mg twice a day over a 3-week period, caused no further change in MAP. After 3 weeks, the fall in MAP (-11 +/- 2%) was maintained by reduced TPR (-26 +/- 6%), whereas cardiac output and stroke volume were increased by 16 +/- 6% and 26 +/- 6%. Renal blood flow and glomerular filtration rate did not change. Beta blockers devoid of PAA lower cardiac output, whereas the elevated TPR in hypertension is unchanged. The hemodynamic profile of pindolol essentially differs from that of beta blockers devoid of PAA.