Fig. 1.
Characteristics of pH-sensitive retrotrapezoid nucleus (RTN) glia in HEPES buffer. A: traces of membrane potential and bath pH show that acidification from 7.3 to 6.9 causes a reversible depolarization. B: summary of H+ effects on membrane potential of pH-sensitive astrocytes (n = 5, *P < 0.05). C: traces of holding current (top) and conductance (bottom) during changes in bath pH show that alkalization increases and acidification decreases outward current and conductance. D and E: current responses to voltage steps from −80 mV to between −40 and −150 mV (E) and corresponding current–voltage (I–V) relationships under alkaline and acidic conditions (D). To isolate the pH-sensitive I–V (♣), we subtract I–V relationships obtained at pH 6.9 (▴) from those recorded at pH 7.5 (■). F: percentage change in conductance during acidification from pH 7.5 to 6.9 observed from all glial cells recorded in the RTN. G: average I–V relationship (n = 5) of pH-sensitive current reverses near the equilibrium potential for K+ (EK+, arrow).