On central control of body fluid homeostasis

The paper is a discussion of the manners in which cerebral receptor systems may perceive the changes in the internal environment which arise in consequence of deviations from fluid balance. Arguments are presented against the current osmoreceptor theory which implies that receptors in the hypothalamic region are stimulated directly by blood hypertonicity. Recent studies are reviewed which indicate that a possible alternative to hypothalamic osmoreceptors may be receptors in the close vicinity of the third ventricle which are influenced by the Na⁺ concentration of the cerebrospinal fluid. Evidence is presented that a sodium sensitive receptor system of this kind participates, not only in the control of water balance, but also in the regulation of the renal Na⁺ excretion and of the arterial blood pressure. The demonstration of a striking central sodium-angiotensin interaction implies that periventricular sodium sensitive receptors also may be a final link in a volumetric regulation of thirst and ADH release which is mediated by the reninangiotensin system.