The effect of purinergic blockers on outward current in isolated
smooth muscle cells of the sheep bladder.
Cotton, K. D., M. A. Hollywood, K. D. Thornbury, and N. G. McHale.
School of Biomedical Science, Queen's University, 97 Lisburn Road,
Belfast, BT9 7BL
APStracts 3:0023C, 1996.
Freshly dispersed cells from the sheep urinary bladder were voltage
-clamped using the whole-cell and inside-out patch clamp technique.
Cibacron and Basilen Blue increased outward current in a dose
-dependent manner with a half maximal response at 10-5 M. Suramin, in
concentrations up to 10-3 M, had no such effect. The Cibacron Blue
response was abolished in Ca2+-free physiological salt solution
suggesting that it was acting on a Ca2+ dependent current. Similarly
the Cibacron Blue-sensitive current was significantly attenuated by
charybotoxin. Cibacron Blue did not modulate inward current nor were
its effects modified by caffeine or heparin suggesting that its
effect on outward current was not secondary to an increase in
intracellular Ca2+. Application of 10-4?M Cibacron Blue to the inside
membrane of excised patches caused a rapid increase in open
probability of a large conductance (300pS) K+ channel. These results
suggest that Cibacron Blue is a potent activator of a Ca2+ dependent
outward current in bladder smooth muscle cells in addition to its
action as a purinergic blocker.
Received 23 August 1995; accepted in final form 29 November 1995.
APS Manuscript Number C522-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 25 January 96