Effect of amphotericin B and Cl- removal on basolateral membrane K+ conductance in frog corneal epithelium.
Increase in stromal K+ concentration from 4 to 79 mM in an in vitro preparation of the frog cornea, in Cl(-)-free solutions, did not change the apical membrane fractional resistance, fR0, or the transepithelial conductance, gt; it depolarized the intracellular potential, V0, by 38 mV and decreased the short-circuit current, Isc by 2.9 microA/cm2. These changes were similar to those observed for the same increase in stromal K+ in control solutions except for the increase in gt in the latter. When stromal K+ was increased with 10(-5) M amphotericin B, AmB, in the tear solution, fR0 increased by 0.27 in control solutions and by 0.08 in Cl(-)-free solutions; respectively, gt increased by 0.40 and by 0.17 mS/cm2; Isc decreased by 12 and by 11 mS/cm2; V0 depolarized by 9 and by 9.5 mV. These results support the concept that: (i) entrance of Cl- into the cell is responsible in part for the bioelectrical changes observed when stromal K+ is increased; and (ii) AmB decreases the partial K+ conductance in the basolateral membrane of the frog cornea epithelium by a decrease in intracellular K+.
Carrasquer
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Department of Medicine (Nephrology) and Physics, University of Louisville, KY 40292.
Wu
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Rehm
W S
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Schwartz
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M
Dinno
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MA
D000666:Amphotericin B / Q000494:pharmacology*; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D002712:Chlorides / Q000378:metabolism*; D003315:Cornea / Q000187:drug effects / Q000502:physiology*; D004553:Electric Conductivity; D004848:Epithelium / Q000187:drug effects / Q000502:physiology; D005110:Extracellular Space / Q000187:drug effects / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects* / Q000502:physiology; D009883:Ophthalmic Solutions; D009994:Osmolar Concentration; D011892:Rana catesbeiana; D013431:Sulfates / Q000494:pharmacology
D002712:Chlorides; D009883:Ophthalmic Solutions; D013431:Sulfates; D000666:Amphotericin B