APStracts 2:0188N, 1995.

Addition of Carbonic Anhydrase Augments Extracellular pH Buffering in Rat Cerebral Cortex. Huang, W., S.E. Smith and M. Chesler. Dept. of Physiology and Neuroscience and Dept. of Neurosurgery, N.Y.U. Medical Center, 550 First Avenue, New York, N.Y. 10016.

APStracts 2:0188N, 1995.

Summary and Conclusions 1. The ability of the extracellular space to buffer rapid alkaline shifts was studied in rat cortex in vitro and in vivo. Alkaline shifts were generated by iontophoresis of OH- or were evoked by pressure ejection of a-amino-3- hydroxy-5-methylisoxazole-4-propionic acid (AMPA). 2. In cortical slices, alkaline shifts induced by OH- were enhanced by the carbonic anhydrase (CA) inhibitor benzolamide (83 16%), and were decreased by superfusion of 10 mg/L CA (-59 4%). CA had no effect at 1 mg/L, and no additional effect at 100 mg/L. 3. In slices, and in vivo, alkaline shifts induced by AMPA were similarly enhanced by benzolamide and decreased by superfusion of CA. 4. These data indicate that extracellular CA activity is less than that required for maximum buffering. This suggests that equilibrium between CO2 and bicarbonate may not be attained during rapid extracellular pH shifts.

Received 6 June 1995; accepted in final form 6 July 1995.
APS Manuscript Number J362-5.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 18 July 1995.