HYDROCEPHALUS DECREASES CHLORIDE EFFLUX FROM THE CHOROID-PLEXUS EPITHELIUM

To explore the novel concept of intrinsic brain regulation of the chor oid plexus (CP), we studied the function of the CP exposed to increase d intracranial pressure (ICP). The function of the CP was evaluated by in vitro chloride (C! ) efflux from isolated CP 21 days after kaolin induced hydrocephalus. The Cl- efflux was significantly decreased in a nimals with elevated intracranial pressure (rate constant, K = 0.024 /- 0.001 s-1) and enlarged ventricles (K = 0.023 +/- 0.001 s-1) compar ed to sham animals (K = 0.031 +/- 0.001 s-1). In contrast, the Cl- eff lux of CP from animals with normal ICP and ventricular size did not di ffer from sham animals. These results illustrate the first demonstrati on of regulation of the CP epithelial function with elevated ICP; they also suggest a brain-CP regulatory mechanism that alters CP function.