Sensors for antidiuresis and thirst-osmoreceptors or CSF sodium detectors?

Abstract

Change in sodium concentration of lateral ventricle CSF caused by intracarotid infusion of hypertonic solutions was measured in conscious sheep. Intracarotid infusion (1.6 ml/min) of 1 M NaCl, 2 M sucrose or 4.6 M or 2 M urea caused progressive increase of CSF sodium concentration, whereas 2 M glucose, 2 M galactose or 0.15 M NaCl did not. Of these solutions, only intracarotid 1 M NaCl or 2 M sucrose caused rapid water intake or rapid decrease in free water clearance. 2 M urea caused relatively slow antidiuresis and no water intake. 4.6 M urea which produced the largest rise of CSF[Na] caused slow antidiuresis and inconsistent small water intake. Infusion into a lateral ventricle (0.05 ml/mi..