Characteristics of two basolateral potassium channel populations in human colonic crypts. Issue 2 (February 1996)

• Record Type: Journal Article
• Authors: Lomax, R B; Warhurst, G; Sandle, G I
• Is Part Of: Gut. Volume 38:Issue 2(1996)
• Page Start: 243
• Page End: 247
• Publication Date: 1996-02
• Subjects: Gastroenterology -- Periodicals; 616.33
• DOI: 10.1136/gut.38.2.243
• Languages: English
• ISSNs: 0017-5749

Abstract

Abstract : The basolateral membrane of human colonic crypt cells contains Ca2+ and cAMP activated, Ba2+ blockable, low conductance (23 pS) K+ channels, which probably play an important part in intestinal Cl- secretion. This study has defined more clearly the basolateral K+ conductive properties of human colonic crypts using patch clamp recording techniques. High conductance (138 pS) K+ channels were seen in 25% of patches (one or two channels per patch), and significantly inhibited by the addition of 5 mM Ba2+, 1 mM quinidine or 20 mM tetraethylammonium chloride (TEA) to the cytosolic side of excised inside-out patches, whereas 1 mM diphenylamine-2-carboxylic acid (DPC) had no effect. In contrast, clusters of the 23 pS K+ channel (two to six channels per patch) were present in > 75% of patches, and channel activity was inhibited by quinidine and DPC, but not by TEA. Activity of the 138 pS K+ channel in inside-out patches was abolished almost completely by removal of bath Ca2+, but in contrast with its effect on the 23 pS K+ channel, addition of 0.1 mM carbachol had no effect on the 138 pS K+ channel in cell attached patches. It is concluded that human colonic crypt cells possess two discrete basolateral K+ channel populations, which can be distinguished by their responses to K+ channel blockers, and their different sensitivities to changes in intracellular Ca2+ concentration.