[Microangiopathy and arterial hypertension in scleroderma and periarteritis nodosa].

The mechanisms of blood pressure regulation in periarteritis nodosa and systemic sclerodermia are discussed in the light of results of personal studies. Hypertension during PAN may be divided into two groups: hypertension related to renal microangiopathy responsible for stimulation of the renin-angiotensin-aldosterone system which often runs a severe course, sometimes accompanied by renal insufficiency and requiring treatment with beta-blocking agents or angiotensin conversion enzyme inhibitors; secondly, hypertension may not be linked to the renin-angiotensin-aldosterone system and the prognosis is then better. In systemic sclerodermia, a similar pattern may be found but it would also seem that the renin-angiotensin-aldosterone system may be stimulated in the absence of any hypertension. This rise in plasma renin activity and aldosterone preceding the onset of an acute sclerodermic renal episode has a very poor prognosis. Corticosteroid therapy may favour such a process. Other regulation mechanisms are also discussed: prostaglandins, bradykinin system.