Effect of furosemide on cerebrospinal fluid composition

Abstract

Electrolyte composition of the cerebral spinal fluid (CSF) is important in central respiratory drive. The relationship between [Cl −] and [HCO 3 −] is of particular interest in maintenance of electrolyte balance. Therefore, the effect of furosemide, an inhibitor of sodium-coupled chloride transport, on CSF electrolyte homeostasis was studied under conditions of normocapnia and hypercapnia in anesthetized dogs. The drug was given intravenously (IV) or in the lateral cerebral ventricles (CV). With normocapnia, there was no change in CSF or arterial P CO 2 , pH, [K +], [Cl −], or [HCO 3 −], while CSF [Na +] decreased 1.7 mM in dogs receiving IV furosemide. With 5% CO 2 breathing and IV furosemide, CSF P CO 2 , pH, [K +], [Cl −], and [HCO 3 −] changed as has been reported for 5% CO 2 breathing alone. 5% CO 2 and CV furosemide, however, led to a greater reduction in CSF [Cl −] and no change in CSF [HCO 3 −]. Thus CV furosemide alters the CSF [Cl −] and [HCO 3 −] in hypercapnia, suggesting that sodium-coupled chloride transport plays a role in regulation of CSF acid-base homeostasis.