Publikationsdatenbank

Regulation of a non-selective cation channel in cells of the ovine rumen epithelium by PGE2 and Forskolin (2005)

Art

Poster

Autoren

Stumpff, F

Brinkmann, I

Martens, H

Kongress

Jahrestagung der Deutschen Physiologischen Gesellschaft

Göttingen, 06. – 09.03.2005

Quelle

Pflügers Archiv : European journal of physiology

Seiten: S116

ISSN: 1432-2013

Sprache

Englisch

Verweise

URL (Volltext): http://www.physiologische-gesellschaft.de/

Kontakt

Institut für Veterinär-Physiologie

Oertzenweg 19 b
14163 Berlin
+49 30 838 62600
physiologie@vetmed.fu-berlin.de

Abstract / Zusammenfassung

We have recently shown that reduction of cytosolic magnesium
enhances current through an apical non-selective cation channel
in ruminal epithelium. To investigate effects of cAMP, cultured
cells were studied using the whole cell configuration of the patchclamp
technique. Cells filled with choline chloride solution
(ChCl) that contained both Mg (0.9 mM) and Na-cAMP (1 mM)
had significantly higher reversal potentials (27±3 mV) than
controls filled with Mg-free solution, with or without cAMP
(p<<0.01). Unlike in cAMP-free controls, both current at -47 mV
and reversal potential were reduced by replacing Na with Ch in
the external solution (p(Na)/p(Ch)=1.09±0.08 (cAMP-free, n=9);
p(Na)/p(Ch)=1.7±0.2 (cAMP, n=11); p=0.01). Internal
application of cAMP doubled permeability of Na versus K from
0.34±0.02 to 0.76±0.04 (p=0.0001, n=4), with corresponding
effects on p(K)/p(Ch). Application of PGE2 (4mM) increased
inward current at -47 mV by -6±1 pA/pF and reversal potential
by 17±1 mV(0.00006, n=7, pipette: Kglu); -15±5 pA/pF and 33±4
mV(p=0.002, n=8, CsCl) and -23±8 pA/pF and 20±1
mV(p=0.0002, n=5, ChCl). Forskolin (10 mM) had similar
effects. We conclude that PGE2, forskolin and elevation of cAMP
increase the selectivity of the non-selective cation channel in
rumen epithelium for sodium. Endogenous cAMP may be
essential for the physiological function of these channels,
allowing uptake of sodium while minimizing efflux of potassium.