Journal article

Publication year: 1999

Pages: 403-408

Journal: Acta physiologica Scandinavica

Volume number: 165

Issue number: 4

ISSN: 0001-6772

DOI Link: https://doi.org/10.1046/j.1365-201x.1999.00523.x

Publisher: Blackwell

Abstract: 
The protein tyrosine kinase inhibitor, genistein, is known to activate the cystic fibrosis transmembrane regulator (CFTR) Cl- channel and to inhibit K+ currents across the rat colonic epithelium. The aim of the present study is to answer the question whether these effects are involved in the regulation of transepithelial K+ transport. Therefore, the action of genistein on K+ transport in rat proximal and distal colon was studied by measuring unidirectional fluxes, uptake and efflux of Rb+ in mucosa-submucosa preparations. All effects of genistein (5 x 10(-5) mol L-1) were tested in the presence of a low concentration of forskolin (2 x 10(-7) mol L-1), because prestimulation of the cAMP pathway has been shown to be a prerequisite for a secretory action of genistein. Forskolin caused an increase in the serosa-to-mucosa flux of Rb+ (J(sm)(Rb)) thereby stimulating net K+ secretion in the proximal and distal colon. None of these effects was further enhanced after administration of genistein. Neither mucosal uptake of Rb+, representing mainly the activity of the H+-K+-ATPase in the distal colon, nor serosal Rb+ uptake, representing, e.g. the activity of the Na+-K+-2Cl(-) cotransporter, were affected by genistein. Also the efflux of Rb+ across the apical or the basolateral membrane, an indicator for the apical and basolateral K+ conductance, was unchanged in the presence of genistein. These results demonstrate that the K+ channels inhibited by genistein are not involved in transepithelial K+ transport.

Harvard Citation style: Heinke, B., Hörger, S. and Diener, M. (1999) The protein tyrosine kinase pathway is not involved in the regulation of K+ transport across the rat colon, Acta physiologica Scandinavica, 165(4), pp. 403-408. https://doi.org/10.1046/j.1365-201x.1999.00523.x

APA Citation style: Heinke, B., Hörger, S., & Diener, M. (1999). The protein tyrosine kinase pathway is not involved in the regulation of K+ transport across the rat colon. Acta physiologica Scandinavica. 165(4), 403-408. https://doi.org/10.1046/j.1365-201x.1999.00523.x