Cardiovascular effects of short-term selective alpha 1-adrenergic blockade with terazosin in patients with essential hypertension.

The effects of selective alpha 1-adrenergic blockade with the agent terazosin on blood pressure and cardiovascular pressor responsiveness as related to major pressor factors were assessed in 17 patients with mild to moderate essential hypertension (mean age +/- s.e.m. 48 +/- 2 years). As compared with a 2-week placebo period, terazosin, given during 8 weeks at a maximal daily dose of 10.5 +/- 1.7 mg, caused a fall of supine arterial pressure (from 153/103 +/- 3/2 to 143/96 +/- 4/2 mmHg; P < 0.05), and a marked blunting of cardiovascular pressor responsiveness to norepinephrine (NE) as judged from the pressor dose (from 0.43 +/- 0.05 to 12.74 +/- 2.93 mmol/kg per min, P < 0.05) and from the shift to the right (P < 0.01) of the correlation relating NE-induced increments of arterial pressure to the corresponding increases of plasma NE during NE infusion. Heart rate, body weight, exchangeable sodium, blood volume, NE plasma clearance, plasma epinephrine, renin, angiotensin (ANG) II and aldosterone levels, the relationships between the ANG II-induced increases in arterial pressure or plasma aldosterone and the concomitant increments of plasma ANG II during ANG II infusion as well as the heart rate responsiveness to isoproterenol did not change significantly after terazosin. The findings of the present study suggest that the fall of arterial pressure induced by selective alpha 1-adrenergic blockade in patients with essential hypertension is associated and probably explained by inhibition of alpha 1-mediated, noradrenergic-dependent vasoconstriction.