Abstract
In young males with essential hypertension, propranolol and pindolol in small doses caused significant expansion of plasma volume (PV) after one month which did not prevent a reduction in BP. With higher doses, changes in PV were inconsistent and reductions in plasma renin activity (PRA) and 24- hour aldosterone excretion (AE) not closely related to BP changes. The effects of β-adrenoreceptor blocking drugs on PV, PRA and AE do not appear to be important components of their anti-hypertensive action