[Primary postural hypotension. Physiopathological study of 8 cases (author's transl)].

Physiological tests showed that both branches of the baroreflex arc-vagal cardiomoderator and, predominantly, sympathetic vasoconstrictor--were affected. There was no rise in serum and urinary noradrenaline levels in standing position, and adrenaline concentrations were rarely increased under induced hypoglycaemia. Dopamine beta-hydroxylase activity and reactivity of the renin-angiotensin-aldosterone system remained normal in most cases. Physiopathologically, the two clinical forms described (i.e. with and without central nervous symptoms) cannot be differentiated.