Objective: 

Extracellular low pH results in lowering of intracellular pH (pH_i). After returning to physiological conditions pH_i recovers rapidly due to several processes. We examined the effects of long-term acidosis on regulation of pH_i in mouse cortical neurons. To investigate the role of H⁺-activated Acid-Sensing Ion Channels (ASICs) in the recovery of pH_i, we challenged wild-type and ASIC1^-/--neurons by acidosis.

Methods: 

After 10–12 days in culture cortical neurons were exposed to prolonged acidosis (pH 6.0) for 1, 6 and >12h prior to pH_i-measurement. Changes of pH_i in response to superfusion with acidic solutions were measured fluorometrically using pH-sensitive 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF).

Results: 

Wild-type and ASIC1^-/- cortical neurons responded to superfusion with acidic solution with a reversible decrease of pH_i. The pH_i response of ASIC1^-/--neurons was altered compared to wild-type neurons. Preconditioning by acidosis affected the time course of pH_i recovery but had different effects in wild-type and ASIC1^-/--neurons. The clearance of acidic pH_i was sensitive to 300 mM amiloride in wild-type and ASIC1^-/--neurons. Exposure to long-term acidosis in the presence of amiloride was performed to determine the contribution of ASICs to preconditioning of neuronal pH_i response.Conclusion:

Our findings indicate that ASICs contribute to the neuronal mechanisms that regulate and maintain pH_i.