[Light-induced hyperpolarization of membrane potential in Nitella flexilis call plasmalemma]

Light-induced hyperpolarization of the membrane potential in Nitella flexilis cell plasmalemma was investigated by the clamping method. It is shown that this response is of an excitation character. The equivalent electric diagram used in the work and the electromotive force included on its basis allowed consideration of two possible (from the common point of view) mechanisms of the response: the action of the electrogenic ion pump and membrane specific permeability to a definite ion. The membrane being in the hyperpolarization state is not capable of acting as a bicarbonate electrode. It is suggested that the response under study is defined by the action of the electrogenic pump, the role of which is performed by HCO2(3)-dependent H+-ATPase with the ion channel as an exciting one.