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E. Monjok, K.K. Kaustubh, K.H. Shivers, G. Kouamou, O. Mgbere, C.A. Opere; Pharmacological Actions of Hydrogen Sulfide on Isolated Porcine Irides . Invest. Ophthalmol. Vis. Sci. 2005;46(13):3684.
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© ARVO (1962-2015); The Authors (2016-present)
Evidence from literature shows that hydrogen sulfide (H2S), a colorless gas with a pungent odor, can produce relaxations of non–ocular smooth muscles of several mammalian species (Moore et al., TIPS 24:609, 2003). Purpose: In the present study, we studied the pharmacological actions of H2S (using sodium hydrosulfide, NaHS and sodium sulfide, Na2S as H2S donors) on contractions of isolated porcine irides induced by carbachol. Methods:Isolated porcine iris muscle strips were set up in organ baths containing oxygenated Krebs buffer solution at 37oC. Longitudinal isometric tension was recorded via a grass FT03 Force–displacement Transducers and analyzed using the Polyview computer software. An initial load of 150 mg was placed on each tissue after which they were allowed to equilibrate for one hour. The relaxant action of NaHS or Na2S on carbachol–induced tone was studied in the absence and presence of an inhibitor of cystathionine γ–lyase (propargylglycine, PAG) and KATP channel antagonist (glibenclamide). Results: In the concentration range, 30 nM to 300 µM, both NaHS and Na2S caused relaxations of tone induced by a submaximal concentration of carbachol yielding IC50 values of 7 µM and 70 µM, respectively. PAG (1 mM) and glibenclamide (100 µM) shifted concentration–response curves to NaHS to the right and depressed its maximum degree of inhibition. Conclusions: Both NaHS and Na2S can elicit inhibitory response in isolated porcine irides, an effect that is dependent on the biosynthesis of H2S in this muscle. Furthermore, the inhibitory action of NaHS in porcine irides is mediated, at least in part, by KATP channels.
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