Efflux of chloride from the rat lens: influence of membrane potential and intracellular acidification.
The efflux of 36C1 from perifused rat lenses consisted of two components: a fast (extracellular) component and a slow (cellular) component. The 36C1 efflux rate constant of the cellular component was 5.7 X 10(-3) min-1. The 36C1- efflux was sensitive to changes in lens potential induced by treatment with high-K+ solutions. The decrease in the 36C1- efflux rate constant caused by high-K+ solutions was consistent with the Goldman model, indicating that, under normal conditions, the majority of the 36C1 efflux is by diffusion. The 36C1- efflux rate constant corresponds to a C1 permeability of 1.3 X 10(8) ms 1. The C1- channel inhibitor anthracene-9-carboxylate (A-9-C), however, caused a relatively small reduction in the efflux rate constant. The anion-exchange inhibitor 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulphonate (SITS) has little effect on the 36C1 efflux under control conditions. Intracellular acidification, induced by pre-treatment with NH1+, leads to a rapid stimulation of 36C1- efflux. This increased 36C1- efflux is blocked by SITS. Thus, it appears that at low intracellular pH (pH), a normally quiescent, SITS-sensitive, anion-exchange mechanism is activated. The possible role of this exchange mechanism in regulating pH, is discussed.
Bassnett
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S
School of Biological Sciences, University of East Anglia, Norwich.
Stewart
S
S
Duncan
G
G
Croghan
P C
PC
D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000494:pharmacology; D000818:Animals; D000873:Anthracenes / Q000494:pharmacology; D001693:Biological Transport, Active / Q000187:drug effects; D002712:Chlorides / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007424:Intracellular Fluid / Q000378:metabolism; D007473:Ion Channels / Q000378:metabolism; D007474:Ion Exchange; D007908:Lens, Crystalline / Q000378:metabolism*; D008564:Membrane Potentials; D010477:Perfusion; D051381:Rats; D011919:Rats, Inbred Strains
D000873:Anthracenes; D002712:Chlorides; D007473:Ion Channels; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; C010030:9-anthroic acid