The light-dependent effect of external pH on the membrane potential of Nitella

• Main Authors: Saito, Kazuyoshi, Senda, Mitsugi
• Format: Text
• Language: English
• Published: Oxford University Press 1973
• Subjects: research-article; Nitella flexilis
• Online Access: http://pcp.oxfordjournals.org/cgi/content/short/14/1/147

In the light the membrane potential of Nitella flexilis and Nitella axilliformis was hyperpolarized by raising the external pH above pH 5.5, at the rate of 30–40 mV /pH below pH 8. This hyperpolarization was largely reduced in the dark. The membrane potential was sensitive to the external pH of media with a low potassium concentration, where it was relatively insensitive to potassium concentration. In media of a high concentration where it was sensitive to the potassium concentration, the membrane became insensitive to the external pH. The transition from a pH-sensitive to a pH-insensitive state occurred rather abruptly on increasing the external potassium concentration.