Intracellular pH and some membrane characteristics of cultured carotid body glomus cells.

Clusters of carotid body (glomus) cells cultured from a few days to 3 weeks, maintained their morphological characteristics during this period. The resting potential (Em) and input resistance (Ro) did not change for 2 weeks but both declined afterwards. The intracellular pH (pHi) of glomus cells, measured with glass microelectrodes filled with an H+ ion exchanger, was 6.34-6.96 at extracellular pH (pHo) of 7.32-7.53. Changes in pHo from normal to about 5.5 depolarized most cells but the fall in pHi was less marked than predicted by the Nernst equation. Conversely, shifting pHo to 8.5 hyperpolarized the cells with an increase in pHi which was more acid than predicted. EH (the calculated equilibrium potential for H+ (Nernst equation) was more positive than Em during acidity and more negative during normal or alkaline pHo. The kinetics of H+ ion distribution was assessed by brief exposures to NH4Cl. It is concluded that hydrogen ions are not passively distributed across the glomus cell membranes and that Em is dependent on H+ ions.