Effects of ouabain, lithium, and cooling on the frog lens fiber potential.

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Abstract
The effects of ouabain, Li+ and cooling on the lens fiber potentials in the anterior and posterior sides were investigated in American bullfrog lens mounted in a special holder using a conventional micropipette technique. Ouabain depolarized the lens fibers in the anterior and posterior sides in a dose- and time-dependent fashion. The fibers at both sides were depolarized in Na-free, Li Ringer. The posterior fibers were depolarized faster than anterior ones during exposure to Ringer solution containing ouabain and Li+. The potential difference observed in the lens fibers of the anterior and posterior sides reduced and disappeared during a successive long exposure to ouabain and Li+. In the presence of ouabain and Li+, the transient potential difference between the anterior and posterior lens fibers depends on the anterior epithelial cell layer, which delays the penetration of ouabain and Li+ into the lens interiors, but not to the difference of total lens surface area in the anterior and posterior exposed to ouabain and Li+. Thermal dependence of the lens fiber potentials at the anterior and posterior sides was 0.78 mV/.degree. C, which is greater than the physical change of 0.2 mV/.degree. C based on the Nernst equation.