Cftr-independent atp release from epithelial cells triggered by
mechanical stimuli.
Grygorczyk, Ryszard, and John W. Hanrahan.
Department of Physiology, McGill University, Montr[theta]al,
Qu[theta]bec H3G 1Y6 Canada
APStracts 3:0393C, 1996.
Cystic fibrosis transmembrane conductance regulator (CFTR)-mediated
ATP efflux has been proposed as an autocrine mechanism for regulating
chloride secretion through other types of chloride channels. Although
we found in previous studies that wild type CFTR channels bathed with
high-ATP solutions do not conduct ATP at rates that can be measured
using the patch clamp technique, those experiments would not have
detected very small or electroneutral ATP fluxes through CFTR, or ATP
efflux through other pathways that might be regulated by CFTR. To
examine these possibilities we have now used a sensitive luciferase
luminometric assay to measure ATP efflux from epithelial and
nonepithelial cell lines. cAMP stimulation did not raise external ATP
concentration above the background noise in any of the cell lines
tested; T84, Calu-3, 9HTEo- and SCFTE29o- (colonic and airway human
epithelial cells, respectively), NIH 3T3 fibroblasts and CHO cells,
nor were variations in ATP release correlated with CFTR expression.
The rate of ATP release was unaffected by cAMP but was exquisitely
sensitive to mechanical perturbations in both CFTR expressing and
non-expressing cells. Mechanically-induced, CFTR-independent ATP
release may be a physiologically relevant mechanism of epithelial
regulation, which has not previously been fully appreciated.
Received 18 October 1996; accepted in final form 22 November
1996.
APS Manuscript Number C598-6.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996