AIMTo explore the effects of different concentrations of lactate on neuronal injury during hypoxia/reoxygenation (H/R) and its mechanism.

METHODSDifferent concentrations of lactate (0, 0.5, 1.0, 2.0, 5.0 mmol/L) were added into medium after different duration of hypoxia, then reoxygenation for 24 h, cell survival rate and LDH release were assayed to determine neuronal damage, moreover, equal concentration of hydrochloric acid were used to mimic the changes of pH brought by lactate for investigating the mechanism of the effects of lactate on neuronal H/R injury.

RESULTSUnder normoxia and H/R 5.0 mmol/L lactate and hydrochloric acid induced or exacerbated neuronal injury. After 12 h and 24 h hypoxia exposure 1.0 mmol/L lactate was shown to be protective, 1.0 mmol/L hydrochloric acid had no effect on neuronal H/R damage.

CONCLUSIONLactate of lower concentration was demonstrated to be neuroprotective during H/R, this protective effect was shown to be due to lactate anions. In contrast, higher concentration of lactate could induce or aggravate neuronal damage under normoxia and H/R, perhaps via the mechanism which involved the changes of pH.