Sodium and hypertension. Still a controversy in 1986.

Interpopulation studies support the hypothesis of a causal relationship between sodium consumption and arterial hypertension. However, although this association has been contradicted by intrapopulation studies, the correlation between sodium and hypertension appears to be genetically determined, as there are both sodium-sensitive and sodium-resistant individuals. Sodium is essential for the maintenance of extracellular and plasma volume equilibrium. It is controlled metabolically by the interaction of several biological systems such as the renin-angiotensin-aldosterone system, the sympathetic nervous system and the kallikrein-kinin and prostaglandin systems. Thus, sodium has a definite role in the mechanism involved in the pathophysiology of the predominantly volume-dependent forms of arterial hypertension. Recently, different structural substances with natriuretic effects have been identified. Natriuretic hormone is a non-peptide substance which inhibits the Na,K-ATPase in response to extracellular volume increase. This hormone acts on the renal tubular cells reducing sodium reabsorption, and at an arteriolar level elevating peripheral resistance by increasing smooth muscle tension. Mammalian atria contain various precursors of biologically active peptides, with potent natriuretic and diuretic effects. They are released in response to volume loading and atrial stretch. Although some data suggest an important role for these natriuretic substances in fluid volume and blood pressure control, their place in physiology and in abnormal clinical states should be more definitively clarified in the next few years.