The Effects of a Beta1‐Blocking Agent, Atenolol, on Blood Pressure, Plasma Renin Activity and Prostaglandin F2α Excretion in Patients with Essential Hypertension

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Abstract
The antihypertensive action of .beta.-blocking agents was suggested to be associated with the decrease in plasma renin activity (PRA) and can be antagonized by indomethacin, a prostaglandin (PG) synthesis inhibitor. The acute and long-term effects of a .beta.1-blocking agent, atenolol (50 mg b.i.d. [twice daily]) on blood pressure (BP), PRA and urinary PGF2.alpha. excretion was studied in 12 male patients (40 yr old) with essential hypertension. BP was measured by a brachial cuff. PRA and PGF2.alpha. were estimated radioimmunologically. One day after the initiation of atenolol treatment, BP fell significantly: the supine values, from 159/114 to 143/104 mmHg and the erect from 158/118 to 140/106 mmHg. In 6 wk BP decreased to 135/94 and 134/96 mmHg, respectively. After the cessation of atenolol for 3 wk BP rose to the pre-atenolol level. When the dose was readjusted (25-150 mg daily for 26 wk) diastolic BP remained at 100 mmHg or higher in 2 patients. During the atenolol treatment PRA declined to 1/3 of the preatenolol level in 1 day and to 1/2 in 6 wk. The urinary excretion of PGF2.alpha. was not affected by atenolol. The antihypertensive action of atenolol and the reduction of PRA apparently are substantial already in 1 day and the decrease in BP or PRA evidently is not associated with PGF2.alpha. production.