Intracellular pH modulates the activity of chloride channels in isolated lacrimal gland acinar cells.
The effects of intracellular pH (pHi) on Ca(2+)-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 ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid. Increasing pH from 6.8 to 7.8 was found to increase whole cell currents. The currents observed exhibited time-dependent activation at depolarizing potentials and time-dependent inactivation at hyperpolarizing potentials (pH 7.8). This behavior is characteristic of Ca(2+)-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 maneuver caused a positive shift in the reversal potential, as expected for a Cl(-)-selective current. Thus increasing pHi appears to activate Ca(2+)-activated Cl- channels. The possibility that an increase in pHi may help sustain Cl- channel activity during secretory activity is discussed.
Park
K
K
School of Biological Sciences, University of Manchester, United Kingdom.
Brown
P D
PD
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D018118:Chloride Channels / Q000187:drug effects / Q000502:physiology*; D004553:Electric Conductivity; D006863:Hydrogen-Ion Concentration; D007765:Lacrimal Apparatus / Q000502:physiology*; D051381:Rats
D018118:Chloride Channels; D000109:Acetylcholine; D002118:Calcium