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Influence of the dietary potassium content on transepithelial potassium transport in rat jejunum
Author(s) -
Cermak R.,
Evelgünne A.,
Scharrer E.
Publication year - 2000
Publication title -
journal of animal physiology and animal nutrition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.651
H-Index - 56
eISSN - 1439-0396
pISSN - 0931-2439
DOI - 10.1046/j.1439-0396.2000.00260.x
Subject(s) - jejunum , medicine , endocrinology , potassium , small intestine , homeostasis , chemistry , ileum , ussing chamber , transcellular , secretion , transepithelial potential difference , biology , ion transporter , biochemistry , organic chemistry , membrane
Summary In a recent study, we found that the distal rat jejunum is able to secrete K + under in vitro conditions. The question therefore arises as to whether the small intestine might participate in K + homeostasis. Consequently, this study examined the influence of the dietary K + content on transepithelial K + transport in rat jejunum. Rats were fed two diets differing in K + content (control diet 4.0 g K + /kg, low K + diet (LK) 0.27 g K + /kg). After a minimal feeding period of 7 days, distal jejunal sheets were mounted in Ussing chambers and unidirectional 86 Rb + fluxes (as a marker for K + transport) were measured under short‐circuit conditions. Jejunum obtained from rats fed the control diet showed a net K + secretion of 200 nmol Rb + /h/cm 2 . Unidirectional Rb + fluxes were smaller in distal jejunum from rats fed the LK diet. In these tissues, glucose‐induced short‐circuit current and tissue conductance were also smaller than in controls. However, net Rb + fluxes were not significantly different in small intestine from K + ‐restricted rats compared with jejunum from control animals. Based on the observation that the dietary K + content does not affect transepithelial net K + transport, we conclude that transcellular K + secretion by the small intestine is not involved in K + homeostasis.