Changes in extracellular pH affect glycine receptor channels expressed in HEK 293 cells

Glycine receptors are expressed throughout the central nervous system working for inhibitory neurotransmission. Since fluctuations of the blood pH value occur under certain physiological and pathological conditions, we investigated the influence of the extracellular pH on glycine homomeric and heteromeric receptor functions using patch clamp in combination with the fast agonist application technique. Our results demonstrated that both alpha1 homomeric and alpha 1 beta heteromeric glycine receptors were remarkably inhibited under acidic extracellular pH. Under alkaline extracellular pH 8.5, there was also a negative functional effect. Desensitization was accelerated depending on pH and a rebound current was observed at an extremely acidic pH value. In double-pulse experiments on alpha1 homomeric receptors, a more rapid recovery of the glycinergic current was shown at pH 4.5 compared to current induced at a physiological pH of 7.2. Our study provided a potential cause for the impaired function of the glycine receptor channels during pH fluctuations occurring in the central nervous system, especially under pathological conditions such as epileptic seizure or ischaemia.