PERIPHERAL BETA-RECEPTOR RESPONSIVENESS IN PATIENTS WITH ESSENTIAL HYPERTENSION

Peripheral .beta.-adrenergic receptor sensitivity was characterized in 24 patients with essential hypertension and in 13 age-matched normotensive subjects using an isoproterenol hydrochloride bolus dose-response technique. Decreased .beta.-receptor responsiveness to this exogenously administered .beta.-agonist was observed in hypertensive patients; for an equivalent chronotropic effect, higher doses of isoproterenol were required in hypertensive subjects than in normal subjects. Among normal-renin hypertensive patients, .beta.-receptor responsiveness was directly related to furosemide-stimulated plasma renin activity (PRA), suggesting that independently stimulated PRA may provide an indirect estimate of endogenous .beta.-receptor sensitivity. Hypertensive patients whose mean arterial pressure fell at least 10 mm Hg after 4 wk of treatment with hydrochlorothiazide had even further depression in .beta.-receptor responsiveness, and receptor sensitivity was unchanged in patients whose blood pressure was unaffected. It is unlikely that this decreased receptor responsiveness in patients with untreated essential hypertension is a direct consequence of elevated arterial pressure.