Role of active transport of chloride in formation of dogfish cerebrospinal fluid.

Abstract

A significant steady state or d.c. potential difference exists between the cerebrospinal and extracellular fluids of the anesthetized dogfish. Since the cerebrospinal fluid is negative with respect to the extracellular fluid and the chloride concentration is greater in cerebrospinal fluid, the formation of cerebrospinal fluid must involve at least one process: active transport of Cl–. While acetazolamide abolishes the gradient of chloride between dogfish cerebrospinal fluid and plasma, its administration did not demonstrably change the potential difference. Though the active transport of Cl– is clearly part of the process of cerebrospinal fluid formation, it is probably only part of the process. No potential difference was observed between dogfish aqueous humor and extracellular fluid.