CYCLIC-AMP ALTERATION OF CHLORIDE TRANSPORT INTO THE CHOROID-PLEXUS CEREBROSPINAL-FLUID SYSTEM

The permeation of Cl-36 from blood into choroid plexus (CP) and cerebrospinal fluid (CSF) was studied in adult rats intraventricularly injected with either dibutyryl (db)-cAMP, theophylline with db-cAMP, or forskolin. All 3 treatments significantly enhanced the 15-min distribution (V(d)) of Cl-36 into CSF, by an average of 17-33%. In contrast, ouabain and acetazolamide (inhibitors of CSF production) reduced Cl-36 uptake into CSF by 34% and 13%, respectively. A correlative analysis of the various treatments revealed that the volume of distribution of Cl-36 in CSF varied inversely with that in the choroid plexus. This inverse relationship suggests drug effects on Cl movement across the apical (CSF-facing) membrane of CP.