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Digitale Medien

Taurocholate depolarizes rat hepatocytes in primary culture by increasing cell membrane Na+ conductance (1993)

Wehner, Frank

Springer

Pflügers Archiv 424 (1993), S. 145-151

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Details

ISSN: 1432-2013

Schlagwort(e): Rat hepatocytes ; Electrophysiology ; Membrane potentials ; Na+ conductance ; Bile acids ; Taurocholic acid

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: Abstract Rat hepatocytes in primary culture were impaled with conventional microelectrodes. Addition of 5–100 μmol/l taurocholate led to a slowly developing depolarization that was maximal at 50 μmol/l (10.5±1.5 mV, n=15) and not reversible. The effect was Na+ dependent and decreased in cells preincubated with 1 μmol/l taurocholate. Increasing external K+ tenfold depolarized the cells by 12.3±2.3 mV under control conditions and by 6.3±1.2 mV with 50 μmol/l taurocholate present (n=7). Depolarization by 1 mmol/l Ba2+ was 7.6±0.8 mV and 6.0±0.7 mV (n=9) before and after addition of taurocholate, respectively. Cable analysis and Na+ substitution experiments reveal that this apparent decrease in K+ conductance reflects an actual increase in Na+ conductance: in the presence of taurocholate, specific cell membrane resistance decreased from 2.8 to 2.3 kΩ · cm2 · Na+ substitution by 95% depolarized cell membranes by 8.9±2.9 mV (n=9), probably due to indirect effects on K+ conductance via changes in cell pH. With taurocholate present, the same manoeuvre changed membrane voltages by −0.8±2.6 mV. When Na+ concentration was restored to 100% from solutions containing 5% Na+, cells hyperpolarized by 3.5±3.6 mV (n=7) under control conditions and depolarized by 4.4±2.9 mV in the presence of taurocholate, respectively. In Cl− substitution experiments, there was no evidence for changes in Cl− conductance by taurocholate. These results show that taurocholate-induced membrane depolarization is due to an increase in Na+ conductance probably via uptake of the bile acid.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00374605

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