Phospholipase C-induced "Na-channels" in the crystalline lens

When present on the posterior side of the lens (in vitro in a divided Ussing-type chamber) phospholipase C increased translenticular p.d. and short-circuit current (SCC) while on the anterior it decreased these parameters. The electrical resistance, Δp.d. ΔSCC, was unchanged. These effects were absent or reduced when the side of the lens exposed to the enzyme was bathed with Na-free, choline Ringer. On the posterior, the enzyme increased Na flux from the posterior to anterior bathing solutions but the Na flux in the opposite direction was unchanged. On the anterior it had the converse effect. Fluxes of K and Cl were unaffected. The enzyme increased the intracellular accumulation of Na when present on either side. Lithium could partly substitute for Na as the effects on p.d. and SCC were still seen. The results are of interest both with respect to the mechanism of Na movement across the lens and the possible nature of "Na-channels" in membranes.