PRESSURE NATRIURESIS FOLLOWING THERAPY FOR ONE-CLIP ONE-KIDNEY HYPERTENSION IN MAN

Decreased renal tubular reabsorption of sodium in response to increase d renal artery perfusion pressure, or ''pressure natriuresis'', has be en demonstrated directly in animal experiments but not in man. In bila teral or single-kidney renovascular hypertension, hypertension has bee n attributed to reduced pressure natriuresis, and a similar mechanism may operate in chronic renal failure. We report a patient who presente d with bilateral renovascular disease and was treated initially by uni lateral nephrectomy. At a second operation the remaining ischemic kidn ey was revascularised. There followed a dramatic natriuresis, sufficie nt to cause clinical and biochemical features of hypovolemia. However, despite the natriuresis, systemic blood pressure remained elevated in the few weeks following surgery. We attribute the natriuresis to incr eased renal artery perfusion pressure, and conclude that acute pressur e natriuresis sufficient to over-ride neurohormonal antinatriuretic me chanisms does occur in man. However, the failure to normalize blood pr essure acutely following the natriuresis suggests that decreased sodiu m excretion is not the only mechanism which maintains hypertension in this unusual syndrome.