[Effect of a beta 1-receptor blocker on the plasma level of atrial natriuretic peptide in patients with essential hypertension in the exercise test].

In order to investigate the behaviour of atrial natriuretic peptide (ANP) in untreated mild to moderate essential hypertension and the influence of blood pressure normalisation by a beta 1-receptor blocker a study was conducted in groups of normotensive and hypertensive middle aged subjects. 10 normal subjects and 10 patients with essential hypertension (WHO I-II) without any medication and on betaxolol monotherapy were studied at rest and during graded exercise. In addition the response of ANP, cyclic guanosine monophosphate (cGMP) and the renin-aldosterone-system was investigated. Normal subjects and hypertensive patients did not differ in ANP levels at rest and also responded with a comparable exercise dependent increase at all workload levels. A steady decrease of ANP was noticed during the recovery period in both groups. After beta-blocker treatment in the hypertensive patients ANP concentrations significantly rose, both at rest and more pronounced during exercise. cGMP reacted in a similar way but showed a more inert response. A counter-regulatory behaviour between ANP and PRA or aldosterone, as seen under volume shifts, could not be detected. These findings demonstrate that plasma ANP is not altered in untreated essential hypertension. Increased ANP levels in beta 1-blocker treatment may contribute to its blood lowering effect.