Localization of cAMP‐ and aldosterone‐induced K⁺ secretion in rat distal colon by conductance scanning

• I. Grotjohann

• A. H. Gitter

• A. Köckerling

• M. Bertog

• J. D. Schulzke

• M. Fromm

抄録

<jats:list list-type="explicit-label"> Aldosterone‐ and adrenaline‐induced K + secretion were investigated in rat late distal colon using conductance scanning and Ussing chamber techniques. K + secretion was unmasked by the K + channel blocker tetraethylammonium (TEA). Electrogenic Na + absorption was inhibited by amiloride. Rb + net fluxes consistently measured about 80 % of K + secretion estimated using change in short‐circuit current (Δ I SC ) measurements. Partial block of K + absorption by mucosal ouabain did not change TEA‐sensitive K + secretion. Thus, K + absorption and K + secretion are not coupled. Additivity of Rb + fluxes as well as Δ I SC caused by 3 nM aldosterone (6 h in vitro incubation) and, subsequently, adrenaline suggested additivity of aldosterone‐induced and cAMP‐mediated K + secretion in the presence of amiloride. Conductance scanning under control conditions revealed a small TEA‐sensitive K + conductivity in surface epithelium (0.3 ± 0.2 mS cm −2 ) but not in crypts, as well as a small basal K + secretion in surface epithelium (Δ I SC = 0.3 μ m ol h −1 cm −2 ), which increased during sham incubation. Aldosterone (3 nM, 6 h in vitro incubation) resulted, after correction for the basal K + secretion, in a K + secretion of Δ I SC = 0.9 μ m ol h −1 cm −2 . Aldosterone induced a TEA‐sensitive conductivity of 1.1 ± 0.3 mS cm −2 in surface epithelium, but not in crypts. Adrenaline (5 μ m ) caused, in fresh tissue, a K + secretion of Δ I SC = 1.2 μ m ol h −1 cm −2 and equal conductivity changes in crypts (0.7 ± 0.2 mS cm −2 ) and surface epithelium (0.7 ± 0.1 mS cm −2 ). We conclude that K + secretion induced by aldosterone in physiological concentration is restricted to surface epithelium, whereas cAMP‐mediated K + secretion is located equally in crypts and surface epithelium.

収録刊行物

• The Journal of Physiology

  The Journal of Physiology 507 (2), 561-570, 1998-03

  Wiley

キーワード

• Physiology

詳細情報

• CRID: 1361137044805022848
• NII論文ID: 30022489078
• DOI: 10.1111/j.1469-7793.1998.561bt.x
• ISSN: 14697793
• ISSN: 00223751
• Web Site: https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1469-7793.1998.561bt.x
• Web Site: https://physoc.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1469-7793.1998.561bt.x
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