Article révisé par les pairs
Résumé : Chara australis was the subject of voltage-clamp experiments in which external calcium, magnesium, and hydrogen were varied. The voltage clamp was applied across the combined plasmalemma, cytoplasm, and tonoplast of internodal cells. Calcium is necessary in the batching medium for transient currents to occur during a depolarizing voltage clamp. Magnesium cannot replace calcium as mediator in this function. Lowering the medium pH appears to affect more than one variable in the membrane system. We argue that more than one ion is responsible for the transient current; large increases in membrane current of sodium, potassium, and chloride occur. © 1970 Oxford University Press.