Effect of Intraventricular Infusions of Artificial Cerebrospinal Fluid on Serum Renin Activity, Aldosterone, Corticosterone, and Prolactin

Renal sodium excretion has been noted to increase with intraventricular infusion of hypernatremic fluid and to decrease with infusion of hyponatremic fluid. To further explore the mechanism of these changes, serum renin activity and serum al-dosterone, corticosterone, and prolactin concentration were measured after 1-hr infusion of artificial cerebrospinal fluid of varying sodium concentration and osmolal-ity into the lateral ventricles of unanesthe-tized rats which had been consuming regular-sodium or low-sodium diets. Serum al-dosterone and prolactin concentrations did not change significantly. Serum renin activity increased with infusion of iso-osmotic, hyponatremic fluid during regular-sodium diet. Serum corticosterone concentration increased during low-sodium diet with infusion of iso-osmotic, hyponatremic and hyper-osmotic, hypernatremic fluid. The failure of serum aldosterone concentration to increase concomitant with increases in serum renin activity and corticosterone concentration suggests that an additional central nervous system factor(s) may influence aldosterone secretion. The mechanism for the changes in renal sodium excretion during intraventricular infusion remains uncertain, but it does not appear to be mediated through aldosterone or prolactin. This research was supported by grants from the American Heart Association, Texas Affiliate; NIH Grant No. RO1-HL18730; and by an institutional grant.