The Kidneys, Volume and Blood Pressure Regulation, and Hypertension

Abstract

Control of blood pressure is complex and time-dependent and involves the integration of numerous physiological factors that contribute to short- and long-term regulations. Experimental studies support a central role for the kidneys in the long-term regulation of arterial pressure and in the pathogenesis of hypertension. A pivotal part of the renal-body fluid feedback control system for long-term volume and pressure regulation is the renal-pressure natriuresis mechanism. Renal-pressure natriuresis is abnormal in all types of experimental and clinical hypertension. Chronically elevated blood pressure or hypertension is an important compensatory mechanism that allows maintenance of sodium balance when renal-pressure natriuresis is impaired. A shift of pressure natriuresis may occur as a result of intrarenal abnormalities such as enhanced formation of angiotensin II, reactive oxygen species, and endothelin (via ETA receptor activation) or decreased synthesis of nitric oxide or natriuretic prostanoids. In other instances, the altered kidney function is caused by extrarenal disturbances, such as increased renal sympathetic nervous activity or excessive formation of antinatriuretic hormones, such as aldosterone. This brief review focuses on the importance of the kidneys in the long-term regulation of blood pressure and briefly summarizes the various intra- and extrarenal factors that contribute to abnormal pressure natriuresis in hypertension.