Effects of SH-group reagents on Ca2+ and K+ channel currents of pancreatic B-cells.
The whole-cell patch-clamp technique has been applied to elucidate the effects of H2O2 and the SH-group reagent 2,2'-dithio-bis(5-nitropyridine) (DTBNP) on Ca2+ currents of mouse pancreatic B-cells. We also tested the effect of DTBNP on the whole-cell K+ ATP current. DTBNP (20 and 100 mumol/l) blocked both the current through Ca2+ channels (with Ba2+ as the charge carrier) and the K+ATP current in a concentration-dependent manner. The results suggest that the channels themselves or regulating proteins possess free SH-groups which may be of functional relevance. However, H2O2 did not influence the Ca2+ channel currents under standard whole-cell conditions as well as when recorded with the perforated patch technique. These results indicate that the two agents act differently on ion channel currents in B-cells although both are known to oxidize SH-groups.
Krippeit-Drews
P
P
Department of Physiology, University of Tübingen, FRG.
Britsch
S
S
Lang
F
F
Drews
G
G
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D015220:Calcium Channels / Q000187:drug effects* / Q000378:metabolism; D005260:Female; D006861:Hydrogen Peroxide / Q000494:pharmacology; D066298:In Vitro Techniques; D007515:Islets of Langerhans / Q000187:drug effects* / Q000378:metabolism*; D008564:Membrane Potentials; D051379:Mice; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology*; D013439:Sulfhydryl Reagents / Q000494:pharmacology*
D015220:Calcium Channels; D015221:Potassium Channels; D011725:Pyridines; D013439:Sulfhydryl Reagents; C011801:2,2'-dithiobis(5-nitropyridine); D000255:Adenosine Triphosphate; D006861:Hydrogen Peroxide