Effects of anion exchange on intracellular ph and tension in
basilar artery of dogs.
Yu, J., B. Y. Ong, J. Zheng, E. J. Cragoe, D. Bose, and R. Bose.
Departments of Pharmacology and Anesthesia, University of Manitoba,
Winnipeg, MB, R3E 0W3, Canada, P.O. Box 1548, Nacogdoches, TX,
USA
APStracts 3:0206H, 1996.
We simultaneously measured intracellular pH (pHi) and isometric
tension in canine basilar arteries. pHi was calculated from the ratio
of fluorescence intensities at 540 nm of exciting wavelengths of 500
and 440 nm in the presence of BCECF (2', 7'- bis - (carboxyethyl)-5,
(6)-carboxyfluorescein). pHi was 7.33 + 0.02 in Krebs-Henseleit
solution (pH of 7.4 and at 37oC). Application of the anion exchange
blocker, 4- acetamido -4' - iso-thiocyanostilbene -2, 2'-disulfonic
acid (SITS) decreased the resting pHi by 0.25 pH units. Increasing
pHo (by decreasing PCO2) from 7.4 to 7.8 increased pHi by 0.38 pH
units and increased the tension by 2.28 + 0.21 mN. Decreasing
extracellular pH (pHo) from 7.8 to 7.4 (by increasing PCO2) restored
the pHi and muscle tension to their baseline levels. SITS inhibited
the increase in pHi and isometric tension in response to the increase
in pHo, in an endothelium-independent fashion. The Na+-H+ exchange
blockers, amiloride or MGCMA (5- (N- methyl- N-
guanidocarbonylmethyl) - amiloride) did not affect the pHo or tension
changes. The results suggest that in the range of pH tested, anion
exchange is more important than Na+-H+ exchange in the regulation of
pHi and mechanical tone in the basilar artery.
Received 31 March 1994; accepted in final form 26 April 1996.
APS Manuscript Number H299-4.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 19 May 96