AJP - Gastrointestinal and Liver Physiology, Vol 263, Issue 4 558-G565, Copyright © 1992 by American Physiological Society
Effects of NH4Cl and dimethylamine on Cl- fluxes in resting and stimulated rat submandibular acinar cells
J. C. Seagrave, S. Barker, M. Curry and J. R. Martinez
Center for Basic and Applied Medical Research, Lovelace Medical Foundation, Albuquerque, New Mexico 87108.
Transmembrane movements of K+ and Cl- in salivary acinar cells are
important in the formation of saliva, and may be affected by changes in
intracellular pH (pHi). Exposure to NH4Cl increases pHi transiently, but
NH4+ may have effects independent of pHi. To investigate how Cl- transport
may be altered under these conditions, rat submandibular acini were exposed
to NH4Cl, and transmembrane Cl- transport was studied with 36Cl-. NH4Cl
increased intracellular Cl- in these cells. The initial phase of this
increase was partially HCO(3-)-dependent and was inhibited by 1 mM
4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), while the
sustained phase was inhibited by 0.1 mM bumetanide. NH4Cl also inhibited
acetylcholine-induced Cl- efflux from tracer preloaded cells. Changes in pH
did not always correlate in time or extent with those of Cl- transport. We
conclude that 1) exposure to NH4Cl increases Cl-uptake primarily by a
bumetanide-sensitive transport system that did not reach steady state
during the experiment, 2) exposure to NH4Cl also stimulates Cl- uptake by a
DIDS-sensitive mechanism, and 3) only the latter is pHi sensitive.
