A new approach to measuring transepithelial potentials in the bovine lens reveals a chloride-dependent component.
A new approach was used to measure anterior and posterior potentials and resistances of the bovine lens. Segments of the anterior, central and posterior lens were studied by mounting a disc of tissue from either the front or the back of the lens in a double chamber. At 35 degrees C the isolated anterior epithelial preparation exhibited a high potential of 9 mV and a low resistance of 279 omega cm2. The lens epithelium can therefore be classified as a 'leaky' or low resistance epithelium. Amiloride, benzamil and furosemide (frusemide) all reduced the anterior transepithelial potential and increased the resistance, amphotericin B (aqueous side) abolished the potential, whereas SITS (4-acetamido-4'-isothiocyanatostilbene-2,2'-disulphonic acid) had no effect. The posterior lens preparation was found to have a 'transepithelial' of -4 mV. This potential and a proportion of the anterior potential were not sensitive to ouabain, amiloride, furosemide, Na+ removal or raised K+, but were abolished by lowering [Cl-] and reduced by the Cl- channel blocker NPPB. We conclude that chloride plays a significant role in the maintenance of transepithelial potentials at both the anterior and posterior surfaces of the lens.
Zhang
J J
JJ
Department of Physiology, University of Wales College of Cardiff.
Jacob
T J
TJ
D000818:Animals; D002417:Cattle; D002463:Cell Membrane Permeability / Q000187:drug effects; D018118:Chloride Channels / Q000037:antagonists & inhibitors / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism*; D004848:Epithelium / Q000187:drug effects / Q000502:physiology; D066298:In Vitro Techniques; D007424:Intracellular Fluid / Q000378:metabolism; D017136:Ion Transport / Q000187:drug effects; D007908:Lens, Crystalline / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009579:Nitrobenzoates / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D018118:Chloride Channels; D002712:Chlorides; D009579:Nitrobenzoates; C058176:5-nitro-2-(3-phenylpropylamino)benzoic acid; D010042:Ouabain; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium