The Renal Circulation

THERE are few vascular beds with such unique anatomic and physiological characteristics as the renal circulation. Although our knowledge has advanced greatly in the past decade, it seems that we may need a man with the imagination and vision of Harvey to explain the multiplicity of unresolved issues in this area. It appears likely that alterations in renal hemodynamics may play a role in the regulation of sodium and water balance and in the maintenance of arterial blood pressure. In addition, the level of renal blood flow may be an important factor in various pathophysiological states. We summarize certain physiological and pathophysiological aspects of the renal circulation.

REGULATION OF RENAL BLOOD FLOW

Approximately 20% of the cardiac output perfuses the renal circulation, an extraordinary amount when one considers that the total weight of both kidneys in man is only 300 g. The maintenance of this blood flow is controlled by