ACUTE EFFECTS OF ALPHA-ADRENOCEPTOR AND BETA-ADRENOCEPTOR BLOCKADE ON PLASMA ATRIAL NATRIURETIC PEPTIDES DURING EXERCISE IN ELDERLY PATIENTS WITH MILD HYPERTENSION

In a randomized study in 26 elderly patients with mild essential hypertension, acute effects of alpha- and beta-adrenoceptor blockade on plasma ANP levels were examined at rest and during ergometric exercise. Plasma ANP level and LVEF were measured before and after administration of prazosin (an alpha-1-adrenergic blocker), atenolol (a cardioselective beta-adrenergic blocker), or carteolol (a nonselective beta-adrenergic blocker). Plasma ANP level was increased by exercise. Carteolol and atenolol increased plasma ANP levels at rest and during exercise, but the effect of atenolol was not statistically significant. Prazosin significantly suppressed the ANP values at rest and during exercise. The LVEF was increased by prazosin and decreased by beta-blockers, especially by carteolol. Multivariate regression analysis showed that LVEF was the most significant predictor of the plasma ANP level at maximal exercise; the resting blood pressure and heart rate were not predictors of this value. The results showed that single administrations of an alpha-blocker and a nonselective beta-blocker had opposite effects on the plasma ANP level both at rest and during exercise in elderly patients with mild essential hypertension. The observed difference in the ANP response seems to be related to changes in left ventricular function rather than changes in blood pressure or heart rate.