Observations on high and low voltage compartments in the crystalline lens of the frog

Abstract

A range of electrical potentials could be measured in the frog lens. The most frequently measured potentials were ∼−30 and ∼−70 mV, with the latter being more predominant. These potentials were designated low and high potential compartments, respectively. The low and high potential compartments depolarized by 18 and 27 mV respectively, when the potassium concentration in the bathing solution was increased from 2·5 to 25 m m. The high potential compartments consistently depolarized when the lens was bathed in calcium-free solutions, whereas certain low potential compartments depolarized and others hyperpolarized. These findings suggested that both the high and low compartment potentials are membrane potentials of lens fibres with different ionic permeability properties. The depolarization of the high and low potential compartments in 25 m m potassium solution had identical time courses with half-times of approximately 100 sec. It can be inferred from these observations that both the high and low compartment membranes lie close to the surface of the lens. A number of low compartment potentials exhibited a rapid hyperpolarizing jump in potential following depolarization to about −15 mV by either high potassium or calcium-free solutions. The behaviour of the potential subsequent to the jump suggested that the compartment had changed from a low to a high potential compartment.