Regulation of β-Adrenergic Receptors

Publisher Website
Google Scholar
Abstract
The cardinal hemodynamic disturbance in established essential hypertension is an increased total peripheral resistance. Monotherapy with conventional p-blockers lowers blood pressure usually without any significant fall in total peripheral resistance. Generally, cardiac output is reduced at rest as well as during exercise. In recent years, p-blockers with vasodilating activity have been developed. Labetalol induces nonselective p-blockade and in addition reduction in vascular resistance mainly through a-blockade. Long-term hemodynamic data indicate gradual normalization of cardiac output, stroke volume, and total peripheral resistance-possibly due to regression of structural changes in the left ventricle and in the arterioles. Prizidilol is a nonselective p-blocker with a direct vasodilator effect. One year results showed a very marked fall in blood pressure and total peripheral resistance and dramatic increase in posttreatment exercise stroke volume. Cardiac output was unchanged in spite of a reduction in heart rate. Due to side effects, the drug has been withdrawn. Dilevalol, which is the R-R‘ isomer of labetalol, is also a nonselective p-blocker, but its vasodilating activity seems to be mainly due to partial p2-agonist activity. Preliminary data indicate a reduction in blood pressure-mainly due to a fall in total peripheral resistance. Studies in elderly patients or in patients with reduced left ventricular function seem to indicate that the drug might be used without deterioration of the heart pump function. Although antihypertensive properties of dilevalol have been extensively studied and are defined, the exact position of dilevalol among antihypertensive drugs will be more precisely determined in future studies.

This publication has 0 references indexed in Scilit: