Intracellular pH (pH(i)) plays an important role in the regulation of central nervous system function. In the present study, we examined whether hydrogen sulfide (H(2)S), a recently recognized neuromodulator, regulates pH(i) in rat primary cultured glia cells. pH(i) was measured with a fluorescent sensitive dye, BCECF-AM. Activities of Cl(-)/HCO(3)(-) exchanger and Na(+)/H(+) exchanger were examined by assessing their capacities to load or extrude H(+) upon NH(4)Cl pulse load. We found that NaHS, a H(2)S donor, decreased pH(i) in a concentration-dependent manner ranging from 10 to 200muM in the primary cultured microglia. Blockade of the Cl(-)/HCO(3)(-) exchanger with, 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) or Na(+)/H(+) exchanger with 5-N-methyl-N-isobutylamiloride (MIA) significantly attenuated the pH(i)-lowering effect of NaHS. Moreover, NaHS significantly increased the activity of Cl(-)/HCO(3)(-) exchanger but inhibited that of Na(+)/H(+) exchanger. The pH regulatory effect of H(2)S was also observed in primary cultured astrocytes, but not in SH-SY5Y neuronal cells. In conclusion, we found for the first time that H(2)S induced intracellular acidification in glia cells via regulation of the activities of Cl(-)/HCO(3)(-) exchanger and Na(+)/H(+) exchanger. The present study may provide new evidence for H(2)S to serve as a neuromodulator and offer a potential approach for the treatment of neurological diseases.
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