Role of the kidney in long-term control of blood pressure

In the central nervous system the afferents signalling either volume in the low pressure system ("cardiopulmonary afferents") or pressure in the arterial system (arterial baroreceptors) interact in a sense of a nonadditive attenuation, and only a complete denervation of both groups of afferents induces a chronic hypertension. Pressure natriuresis seems to contribute significantly in avoiding excessive hypertension in many states of chronic sodium and water retention. The variables threshold pressure and slope of the "renal baroreceptor"--mechanism of renin release serve different physiological functions: changes in slope (sensitivity) counteract short term changes in sodium balance whereas threshold pressure ensures a minimal systemic blood pressure associated with normal glomerular filtration. Sympathetic "resetting" of threshold pressure may play a pathophysiological role in some forms of hypertension and in the sodium retention of early congestive heart failure.