Hydrogen sulfide regulates intracellular pH in rat primary cultured glia cells

Intracellular pH (pHi) plays an important role in the regulation of central nervous system function. In the present study, we examined whether hydrogen sulfide (H2S), a recently recognized neuromodulator, regulates pHi in rat primary cultured glia cells. pHi was measured with a fluorescent sensitive dye, BCECF-AM. Activities of Cl−/HCO3− exchanger and Na+/H+ exchanger were examined by assessing their capacities to load or extrude H+ upon NH4Cl pulse load. We found that NaHS, a H2S donor, decreased pHi in a concentration-dependent manner ranging from 10 to 200 μM in the primary cultured microglia. Blockade of the Cl−/HCO3− exchanger with, 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid (DIDS) or Na+/H+ exchanger with 5-N-methyl-N-isobutylamiloride (MIA) significantly attenuated the pHi-lowering effect of NaHS. Moreover, NaHS significantly increased the activity of Cl−/HCO3− exchanger but inhibited that of Na+/H+ exchanger. The pH regulatory effect of H2S was also observed in primary cultured astrocytes, but not in SH-SY5Y neuronal cells. In conclusion, we found for the first time that H2S induced intracellular acidification in glia cells via regulation of the activities of Cl−/HCO3− exchanger and Na+/H+ exchanger. The present study may provide new evidence for H2S to serve as a neuromodulator and offer a potential approach for the treatment of neurological diseases.