Effects of NH4Cl and dimethylamine on Cl- fluxes in resting and stimulated rat submandibular acinar cells.
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.
Seagrave
J C
JC
Center for Basic and Applied Medical Research, Lovelace Medical Foundation, Albuquerque, New Mexico 87108.
Barker
S
S
Curry
M
M
Martinez
J R
JR
D000109:Acetylcholine / Q000494:pharmacology; D000643:Ammonium Chloride / Q000494:pharmacology*; D000818:Animals; D000838:Anions / Q000037:antagonists & inhibitors / Q000378:metabolism; D002352:Carrier Proteins / Q000037:antagonists & inhibitors; D002712:Chlorides / Q000378:metabolism*; D004123:Dimethylamines / Q000494:pharmacology*; D005110:Extracellular Space / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007474:Ion Exchange; D007477:Ions; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012146:Rest; D028021:Sodium-Potassium-Chloride Symporters; D013363:Submandibular Gland / Q000166:cytology / Q000378:metabolism*
D000838:Anions; D002352:Carrier Proteins; D002712:Chlorides; D004123:Dimethylamines; D007477:Ions; D028021:Sodium-Potassium-Chloride Symporters; D000643:Ammonium Chloride; C034516:dimethylamine; D000109:Acetylcholine