Cyclic AMP alteration of chloride transport into the choroid plexus-cerebrospinal fluid system

The permeation of 36Cl 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 (Vd) of 36Cl into CSF, by an average of 17-33%. In contrast, ouabain and acetazolamide (inhibitors of CSF production) reduced 36Cl uptake into CSF by 34% and 13%, respectively. A correlative analysis of the various treatments revealed that the volume of distribution of 36Cl 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.