Reconstitution of single potassium channels from bovine gall-bladder epithelium.
The study of molecular transport across gall-bladder epithelium may contribute to our understanding of the pathophysiology of gall-bladder disease. The aim of this study was to reconstitute and characterize single potassium ion channels in bovine gall-bladder epithelial mucosa - both apical and basolateral aspects. Standard subcellular fractionation techniques were used to form either apical or basolateral closed-membrane vesicles from the mucosal epithelium of fresh gall bladders from healthy young adult cattle. Vesicular ion channels were incorporated into voltage-clamped planar lipid bilayers under known ionic conditions and their conductances, reversal potentials, and voltages were characterized. Low-conductance voltage-insensitive apical membrane vesicle channels of at least four conductance levels were found (mean +/- SD): 12+/-4 pS, n = 10; 40+/-12 pS, n = 4; 273+/-31 pS, n = 3; and 151+/-24 pS, n = 5. Conductances of potassium ion channels in basolateral membrane vesicles were in the range 9 - 450 pS, and these channels included high-conductance calcium-activated potassium-ion channels 'K(Ca)' which were voltage- and calcium-dependent.
Kyriacou
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Department of Medicine, Royal Infirmary of Edinburgh, Scotland, UK.
D000818:Animals; D002417:Cattle; D004847:Epithelial Cells / Q000502:physiology*; D005704:Gallbladder / Q000502:physiology*; D015640:Ion Channel Gating; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000502:physiology*
D015221:Potassium Channels