Regulation of [3H] d-Aspartate Release from Mammalian Isolated Retinae by Hydrogen Sulfide

摘要

Hydrogen sulfide (H₂S), can produce pharmacological effects on neural and non-neural tissues from several mammalian species. The present study investigates the pharmacological action of H₂S, (using sodium hydrosulfide, NaHS, and/or sodium sulfide, Na₂S as donors) on amino acid neurotransmission (using [3H] d-aspartate as a marker for glutamate) from isolated, superfused bovine and porcine retinae. Isolated neural retinae were incubated in Krebs solution containing [3H] d-aspartate at 37°C. Release of [3H] d-aspartate was elicited by high potassium (K+ 50 mM) pulse. Both NaHS and Na₂S donors caused an inhibition of K+-evoked [3H] d-aspartate release from isolated bovine retinae without affecting basal [3H] d-aspartate efflux yielding IC₅₀ values of 0.006 and 6 μm, respectively. Furthermore, NaHS inhibited depolarization-evoked release of [3H] d-aspartate from isolated porcine retinae with an IC₅₀ value of 8 μM. The inhibitory action of NaHS on [3H] d-aspartate release from porcine retinae was blocked by propargyglycine, a selective inhibitor of cystathionine γ-lyase (CSE). Our results indicate that H₂S donors can inhibit amino acid neurotransmission from both isolated bovine and porcine retinae, an effect that is dependent, at least in part, on intramural biosynthesis of H₂S.