Single-channel currents activated by low intracellular pH in cultured hippocampal neurons of rat

Patch clamp technique was applied to the plasma membrane of cultured hippocampal neurons of rat. Elementary currents of a cation-selective channel were elicited by low intracellular pH (pHi 3.5-4.5). Channel activity starts with 1-2 min delay from the application of low pHi, and persists upon restoration of physiological pH conditions. The channel has a conductance of approx. 110 pS in symmetrical 300 mM NaCl, and is strongly selective for cations over anions. The channel is active over the whole voltage range tested (from +75 mV to -75 mV). Mean open time is function of voltage, increasing with depolarization. Low pH applied extracellularly did not activate the channel.