[Effect of betaxolol on atrial natriuretic peptide regulation in patients with essential hypertension].

Plasma levels of human atrial natriuretic peptide (ANP) were measured in 10 patients with mild essential hypertension (EH) (WHO I). The renin-angiotensin-aldosterone-(RAA) system and ANP were investigated in a sequential study without treatment and under administration of a cardioselective beta-blocker (betaxolol). We analyzed the RAA system and ANP under conditions of volume loading induced by 2000 ml saline and volume depletion induced by 40 mg furosemide iv. Volume depletion induced a stimulation of the RAA-system but the ANP levels decreased from 87 +/- 13.6 to 55 +/- 7.6 pg/ml. Volume loading induced a suppression of the RAA-system but caused a rise of ANP from 47 +/- 12 pg/ml to 133 +/- 30 pg/ml. Under application of betaxolol the RAA system was suppressed and ANP levels were increased, but physiological volume regulation was maintained. Although blood pressure and heart rate were lowered under administration of betablockers, the ANP levels were increased. These results suggest that increased ANP in plasma under administration of betaxolol may play a role in compensatory mechanisms in response to beta-adrenergic blockade.