Hydrogen sulfide increases calcium-activated potassium (BK) channel activity of rat pituitary tumor cells.
Hydrogen sulfide (H(2)S) is the third gasotransmitter found to be produced endogenously in living cells to exert physiological functions. Large conductance (maxi) calcium-activated potassium channels (BK), which play an important role in the regulation of electrical activity in many cells, are targets of gasotransmitters. We examined the modulating action of H(2)S on BK channels from rat GH(3) pituitary tumor cells using patch clamp techniques. Application of sodium hydrogen sulfide as H(2)S donor to the bath solution in whole cell experiments caused an increase of calcium-activated potassium outward currents. In single channel recordings, H(2)S increased BK channel activity in a concentration-dependent manner. Hydrogen sulfide induced a reversible increase in channel open probability in a voltage-dependent, but calcium independent manner. The reducing agent, dithiothreitol, prevented the increase of open probability by H(2)S, whereas, the oxidizing agent thimerosal increased channel open probability in the presence of H(2)S. Our data show that H(2)S augments BK channel activity, and this effect can be linked to its reducing action on sulfhydryl groups of the channel protein.
Department of Physiology of Man and Animals, Kazan State University, Kremlevskaya 18, Kazan 420008, Russia.
Guzel F
GF
Sitdikova
Thomas M
TM
Weiger
Anton
A
Hermann
D000393:Air Pollutants / Q000494:pharmacology; D000818:Animals; D002460:Cell Line; D004229:Dithiothreitol / Q000494:pharmacology; D005260:Female; D006801:Humans; D006862:Hydrogen Sulfide / Q000494:pharmacology*; D015640:Ion Channel Gating / Q000187:drug effects*; D051036:Large-Conductance Calcium-Activated Potassium Channels / Q000378:metabolism*; D008297:Male; D010084:Oxidation-Reduction; D018408:Patch-Clamp Techniques; D010911:Pituitary Neoplasms / Q000378:metabolism* / Q000473:pathology; D051381:Rats; D013849:Thimerosal / Q000494:pharmacology
D000393:Air Pollutants; D051036:Large-Conductance Calcium-Activated Potassium Channels; D013849:Thimerosal; D004229:Dithiothreitol; D006862:Hydrogen Sulfide