Pharmacological Actions of Hydrogen Sulfide Donors on Sympathetic Neurotransmission in the Bovine Anterior Uvea, In Vitro.

In the present study, we investigated the effect of three different sources of hydrogen sulfide (H2S) on sympathetic neurotransmission from isolated superfused bovine iris-ciliary bodies. The three agents under consideration were: ACS67, a hybrid of latanoprost and a H2S-donating moiety; L-cysteine, a substrate for endogenous production of H2S and GYY 4137, a slow donor of H2S. We also examined the contribution of prostaglandins to the pharmacological actions of the H2S donors on release of [(3)H]-norepinephrine ([(3)H]NE) triggered by electrical field stimulation. ACS67, L-cysteine and GYY 4137 caused a concentration-dependent inhibition of electrically-evoked [(3)H]NE release from isolated bovine iris-ciliary bodies without affecting basal [(3)H]NE efflux. The cyclooxygenase inhibitor, flurbiprofen enhanced the inhibitory action of ACS67 and L-cysteine on stimulated [(3)H]NE release. Both aminooxyacetic acid, an inhibitor of cystathionine-ß-synthase and glibenclamide, a KATP channel blocker reversed the inhibition of evoked NE release induced by the H2S donors. We conclude that H2S donors can inhibit sympathetic neurotransmission from isolated bovine iris-ciliary bodies, an effect partially dependent on the in situ production of H2S and prostanoids, and is mediated by an action on KATP channels.