[Temperature characteristics of ouabain-insensitive sodium flux in frog muscle]

Temperature influence on ouabain-insensitive non-diffusion sodium efflux from the frog skeletal muscle loaded by sodium was studied. It is puzzling that the up-gradient sodium efflux supplied by enzymatic reaction is characterized by low temperature coefficient (Q10 = 1.3). This contradiction was overcome by an introduction of diffusion channel in the sodium transport scheme. It is supposed that the enzymatic reaction occurs at inner membrane boundary and the sodium ion is translocated into the channel. Afterwards the sodium ions come out by diffusion. According to our calculation the energy needed for the ion translocation approximately 13 kkal/mol and its value does not depend on temperature. But temperature affects the sodium diffusion through the channel and thus the low temperature coefficient of sodium extrusion is explained.