KINETICS OF POTASSIUM MOVEMENT ACROSS AMPHIBIAN LENS MEMBRANES

Influx studies with the isotope 42K show that at least 90% and most likely all of the amphibian lens potassium is readily exchangeable. It has also been shown that, for at least 24 hr, the system is in a steady-state with respect to potassium ions. The potassium efflux is sensitive to changes in ion concentrations in the bathing solution; generally the efflux rate increases when the lens is depglarised. The efflux in sodium-free media, however, increases, although the lens hyperpolarizes. The efflux is not sensitive to short-term exposures to solutions containing 2,4 dinitrophenol (DNP) or ouabain, and this confirms that the potassium ions move outwards passively across the membranes. © 1969.