Further Evidence for the Importance of CSF Na+ Concentration in Central Control of Fluid Balance

Slow (0.05 ml/min) infusions of hypo‐, iso‐, and hypertonic solutions of d‐glucose, fructose and sucrose into the CSF of the lateral cerebral ventricle of the goat were found to repress the dipsogenic, antidiuretic and natriuretic responses to intracarotid infusions of hypertonic NaCl. Corresponding intraventricular infusions of slightly hypotonic (0.14 M) NaCl, and of 0.3 M d‐glucose in 0.14 M NaCl did not have this repressive effect. The results are taken as support for the idea that a central receptor system, which is sensitive to variations in the Na+ concentration of the CSF, plays an important role in the control of body fluid homeostasis.