Receptor for protons in the membrane of sensory neurons.

The neurons isolated from spinal ganglia and from the ganglion of trigeminal nerve of a rat were investigated in the conditions of intracellular perfusion and voltage clamp. Many cells responded to rapid changes of the external pH from 7.4 to l.9 and lower values by pH-dependent desensitizing inward current. This current was saturated at pH 5.4 (pKa 6.2) and carried by Na+ and K+ ions )PK:PNa approximately equal to 0.1). The discovered mechanism is capable of producing depolarization of the neuronal membrane in response to a weak acidification of the external medium.