The autonomic nervous system and pressure-natriuresis in cardiovascular-renal interactions in response to salt.

The maintenance of cardiovascular homeostasis represents a balance of activities between of the heart, vascular system and the kidneys in the control of extracellular fluid volume and ultimately blood pressure. Any disturbance in the function of these organs can lead to hypertension and heart failure. Interaction between the cardiovascular and renal systems is exerted dynamically by the autonomic nervous system and humoral factors which together determine the slope of the pressure-natriuresis relationship. This allows the body to ensure that dietary sodium intake can be excreted efficiently without causing major changes in blood pressure. Autonomic control of the kidney is exerted via the renal sympathetic nerves modulating renin release, sodium reabsorption and renal haemodynamics. Epidemiological studies have suggested a weak relationship between the level of dietary sodium intake and the development of hypertension, the underlying mechanisms are uncertain. It is evident from experimental studies that an elevation in dietary sodium intake during the growing phase heightens neural control of blood pressure and the kidney partly due to an enhanced role of the brain renin-angiotensin system. The relationship between dietary sodium and the autonomic regulation of blood pressure and the kidney is increasingly recognised as important but is only poorly understood.