Journal article

Publication year: 2001

Pages: 445-458

Journal: Acta physiologica Scandinavica

Volume number: 171

Issue number: 4

ISSN: 0001-6772

DOI Link: https://doi.org/10.1046/j.1365-201X.2001.00806.x

Publisher: Blackwell

Abstract: 
The effect of cell swelling and cell shrinkage on K+ transport across the rat colonic epithelium was studied by measuring unidirectional fluxes, uptake and efflux of Rb-86(+), a marker for K+. Exposure to a hypotonic medium stimulated the secretory, serosa-to-mucosa flux of K+, whereas exposure to a hypertonic medium inhibited the absorptive, mucosa-to-serosa flux of K+ in the distal, but not in the proximal colon. Neither manoeuvre had any effect on the uptake of K+ across the apical or the basolateral membrane. Cell swelling induced a sustained increase in the apical and basolateral K+ efflux from both colonic segments, whereas cell shrinkage reduced the efflux. Ba2+ (10(-2) mol l(-1)) inhibited the swelling-induced stimulation of the apical, quinine (10(-3) mol l(-1)) that of the basolateral K+ efflux in the distal colon. Incubation of the tissue in Ca2+-free buffer or La3+, which blocks Ca2+-influx into the epithelium, strongly reduced the basal K+ efflux across the basolateral membrane. The same was observed with brefeldin A, a blocker of the transport of newly synthesized proteins out of the endoplasmatic reticulum. Swelling-induced K+ efflux, however, was not reduced. In the presence of colchicine, an inhibitor of the polymerization of microtubules, swelling evoked only a transient increase in mucosal efflux, which, especially in the proximal colon, fell after 6 min to the level of the isotonic control period. These results demonstrate that the cell volume is involved in the regulation of transepithelial K+ transport across the rat colonic epithelium and suggest a role of the cytoskeleton in the control of a part of the volume-sensitive K+ channels.

Harvard Citation style: Ribeiro, R., Heinke, B. and Diener, M. (2001) Cell volume-induced changes in K+ transport across the rat colon, Acta physiologica Scandinavica, 171(4), pp. 445-458. https://doi.org/10.1046/j.1365-201X.2001.00806.x

APA Citation style: Ribeiro, R., Heinke, B., & Diener, M. (2001). Cell volume-induced changes in K+ transport across the rat colon. Acta physiologica Scandinavica. 171(4), 445-458. https://doi.org/10.1046/j.1365-201X.2001.00806.x