Rapid Publication to the Journal of Neurophysiology Benzolamide Inhibits
Low-Threshold Calcium Currents in Hippocampal Pyramidal Neurons.
Gottfried, J.A. and M. Chesler.
Dept. of Physiology and Neuroscience and Dept. of Neurosurgery, NYU Medical
Center, 550 First Avenue, New York, NY 10016.
APStracts 2:0291N, 1995.
SUMMARY AND CONCLUSIONS
1. Benzolamide is a poorly-permeant sulfonamide inhibitor of the enzyme
carbonic anhydrase. We studied the effect of benzolamide on low-threshold (LT)
Ca currents in neonatal hippocampal CA1 neurons. 2. In hippocampal slices,
benzolamide (2-10 mM) inhibited the LT current 30 - 75 percent in voltage-
clamped CA1 pyramidal cells (n=6). In slices bathed in HEPES-buffered Ringer,
benzolamide also reduced the LT current, indicating that the action of the
drug was not bicarbonate-dependent. 3. Benzolamide inhibited LT Ca currents 20
- 75 percent in acutely dissociated CA1 neurons in HEPES (n = 18): inhibition
was 36 8 percent (n = 7) and 50 8 percent (n = 7) at 10 and 50 mM
benzolamide, respectively. By contrast, high-threshold (HT) calcium currents
recorded in CA1 pyramidal cells (n = 18) and dorsal root ganglion(DRG) neurons
(n = 4) were virtually unaffected by benzolamide. 4. These results indicate
that benzolamide inhibits LT Ca channels in central neurons, and suggest
caution in the use of this agent to inhibit extracellular carbonic anhydrase
in excitable tissues.
Received 30 August 1995; accepted in final form 26 September 1995.
APS Manuscript Number J575-5.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95