Intracellular ph modulates the activity of chloride channels in isolated lacrimal gland acinar cells. Park, Kyungpyo, and Peter D. Brown. Cell Physiology Group, School of Biological Sciences, University of Manchester, Manchester M13 9PT, U.K.
APStracts 2:0005C, 1995.
The effects of intracellular pH (pHi) on Ca2+-activated Cl- currents in rat lacrimal gland acinar cells were examined. Cl- currents were recorded by conventional whole-cell patch clamp methods using K+-free and Na+-free solutions. pHi was varied by using electrode solutions with pH at 6.8, 7.3 or 7.8, and Ca2+ activity was buffered at 100 nM with EGTA. Increasing pH from 6.8 to 7.8 was found to increase whole-cell currents. The currents observed exhibited time-dependent activation at depolarising potentials, and time -dependent inactivation at hyperpolarising potentials (pH 7.8). This behaviour is characteristic of Ca2+-activated Cl- channels in lacrimal gland cells. The selectivity of the current was examined at pH 7.8 by removing Cl- from the bath solution. This manoeuvre caused a positive shift in the reversal potential, as expected for a Cl--selective current. Thus, increasing pHi appears to activate Ca2+-activated Cl- channels. The possibility that an increase in pHi may help sustain Cl- channel activity during secretory activity is discussed. 

Received 21 August 1994; accepted in final form 7 November 1994
APS Manuscript Number C0568-4.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1994 The American Physiological Society.
Published in APStracts on 27 February 1995.