| 19919833 |
Dhaese I, Van Colen I, Lefebvre RA: Mechanisms of action of hydrogen sulfide in relaxation of mouse distal colonic smooth muscle. Eur J Pharmacol. 2010 Feb 25;628(1-3):179-86. Epub 2009 Nov 15.
Hydrogen sulfide (H (2) S) has been suggested as a gaseous neuromodulator in mammals. The aim of this study was to examine the influence of H (2) S on contractility in mouse distal colon. The effect of sodium hydrogen sulfide (NaHS; H (2) S donor) on prostaglandin F (2alpha) (PGF (2alpha))-contracted circular muscle strips of mouse distal colon was investigated. In addition, tension and cytosolic calcium concentration ([Ca (2+)](cyt)) in the mouse distal colon strips were measured simultaneously in the presence of NaHS. NaHS caused concentration-dependent relaxation of the pre-contracted mouse distal colon strips. The NaHS-induced relaxation was not influenced by the K (+) channels blockers glibenclamide, apamin, charybdotoxin, barium chloride and 4-aminopyridine. The relaxation by NaHS was also not influenced by the nitric oxide inhibitor L-NAME, by the soluble guanylate cyclase respectively adenylate cyclase inhibitors ODQ and SQ 22536, by the nerve blockers capsazepine, omega-conotoxin and tetrodotoxin or by several channel and receptor blockers (ouabain, nifedipine, 2-aminoethyl diphenylborinate, ryanodine and thapsigargin). The initiation of the NaHS-induced relaxation was accompanied by an increase in [Ca (2+)](cyt), but once the relaxation was maximal and sustained, no change in [Ca (2+)](cyt) was measured. This calcium desensitization is not related to the best known calcium desensitizing mechanism as the myosin light chain phosphatase (MLCP) inhibitor calyculin-A and the Rho-kinase inhibitor Y-27632 had no influence. We conclude that NaHS caused concentration-dependent relaxations in mouse distal colon not involving the major known K (+) channels and without a change in [Ca (2+)](cyt). This calcium desensitization is not related to inhibition of Rho-kinase or activation of MLCP. |
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