Comparison of the effects of methanethiol and sodium sulphide on uterine contractile activity

Abstract

Background: Our aim was to investigate the effect of methanethiol (CH3SH) on contractility of rat uterus and activities of redox-active enzymes, and to compare them with the effect of sodium sulphide (Na2S), a hydrogen sulphide (H2S/HS-) donor. Methods: Uteri were isolated from virgin Wistar rats, divided into six groups, controls (untreated uteri allowed to contract spontaneously and in the presence of Ca2+(6 mM)), CH3SH treated (spontaneously active and Ca2+ induced) and Na2S treated (spontaneously active and Ca2+ induced). Underlying antioxidative enzyme activities (superoxide dismutase - SOD, glutathione peroxidase - GSHPx, glutathione reductase - GR) in CH3SH- or Na2S-treated uteri were compared to controls. Results: Our experiments showed that CH3SH and Na2S provoked reversible relaxation of both spontaneous and Ca2+ induced uterine contractions. The dose-response curves differed in shape, and CH3SH curve was shifted to higher concentration compared to H2S/HS-. The effects of Na2S fitted sigmoid curve, whereas those of CH3SH fitted linearly. CH3SH provoked increased SOD activity and decreased GR activity. However, Na2S (H2S/HS-) provoked an increase in SOD activity exclusively in Ca2+ stimulated uteri, while the activity of GSHPx was increased in both types of active uteri. Conclusion: Our results imply that CH3SH may have a constructive role in the control of muscle function and metabolism. Observed differences between CH3SH and H2S/HS- could be attributed to a larger moiety that is present in CH3SH compared to H2S, but they are more likely to be a consequence of the specific actions of HS-, in relation to its negative charge.