Effect of Hydrogen Sulfide on Sympathetic Neurotransmission and Catecholamine Levels in Isolated Porcine Iris-Ciliary Body

Abstract

In the present study, we investigated the pharmacological action of hydrogen sulfide (H2S, using sodium hydrosulfide, NaHS, and/or sodium sulfide, Na2S as donors) on sympathetic neurotransmission from isolated, superfused porcine iris-ciliary bodies. We also examined the effect of H2S on norepinephrine (NE), dopamine and epinephrine concentrations in isolated porcine anterior uvea. Release of [3H]NE was triggered by electrical field stimulation and basal catecholamine concentrations was measured by high performance liquid chromatography (HPLC). Both NaHS and Na2S caused a concentration-dependent inhibition of electrically evoked [3H]NE release from porcine iris-ciliary body without affecting basal [3H]NE efflux. The inhibitory action of H2S donors on NE release was attenuated by aminooxyacetic acid (AOA) and propargyglycine (PAG), inhibitors of cystathionine beta-synthase (CBS) and cystathionine gamma-lyase (CSE), respectively. With the exception of dopamine, NaHS caused a concentration-dependent reduction in endogenous NE and epinephrine concentrations in isolated iris-ciliary bodies. We conclude that H2S can inhibit sympathetic neurotransmission from isolated porcine anterior uvea, an effect that is dependent, at least in part, on intramural biosynthesis of this gas. Furthermore, the observed action of H2S donors on sympathetic transmission may be due to a direct action of this gas on neurotransmitter pools.

Effect of Hydrogen Sulfide Donors on Intraocular Pressure in Rabbits

“…It is tempting to speculate that due to its ability to modify sympathetic neurotransmission, an effect of H 2 S on nerve activity and/or neurotransmitter pools in the anterior uvea may account, at least in part, for its action on IOP. 10 We conclude that H 2 S-releasing compounds can lower IOP in normotensive animals. The slow-releasing H 2 S compound, GYY 4137, displayed a profile of action that took a longer time to reach maximal reduction in IOP and a longer time to recover from its action.…”

“…For instance, H 2 S can alter neurotransmitter release from tissues of the anterior uvea and retina and can exert a neuroprotective action in the retina. 10,[15][16][17]19,27,28 There is evidence that H 2 S can relax both isolated mammalian irides and posterior ciliary arteries.…”

“…In the anterior uvea, H 2 S donors such as NaHS and Na 2 S inhibited fieldstimulated [ 3 H] norepinephrine release and reduced catecholamine concentrations from isolated porcine iris-ciliary bodies. 10 The ability of H 2 S donors to reduce sympathetic output was blocked by inhibitors of CSE and CBS, indicating that endogenously produced H 2 S is involved in this response. 10 At postjunctional sites, H 2 S donors and its substrate, lcysteine, have also been reported relax precontracted isolated porcine irides, an effect that was partially dependent upon endogenous biosynthesis of H 2 S in this tissue.…”

“…10 The ability of H 2 S donors to reduce sympathetic output was blocked by inhibitors of CSE and CBS, indicating that endogenously produced H 2 S is involved in this response. 10 At postjunctional sites, H 2 S donors and its substrate, lcysteine, have also been reported relax precontracted isolated porcine irides, an effect that was partially dependent upon endogenous biosynthesis of H 2 S in this tissue. 11,12 Furthermore, in bovine posterior ciliary arteries, H 2 S donors such as NaHS, GYY 4137, AP67, and AP72 have been shown to relax phenylephrine-induced tone by an action that is partially dependent upon the endogenous production of H 2 S, prostanoids, and K ATP channels.…”

Effect of Hydrogen Sulphide Donor on Intraocular Pressure in Rats

“…[15] показали, що донор сірководню гідросульфід натрію знижував концентрацію норадреналіну і адреналіну в ізольованих препаратах райдужки -циліарного тіла з очей свині. Було відмічено релаксуючу дію NaHS і Na 2 S на гладенькі м'язи циліарного тіла і райдужки.…”