Localization of potassium and sodium fluxes in the rat lens

A three chambered Ussing-type apparatus was devised so that a lens could be exposed to test media at the anterior surface, the posterior surface, and the equatorial surface. Potassium and sodium fluxes were estimated with double isotope labeling. 86Rb, which behaves like potassium, or 22Na were used for flux measurements, and 3H-inulin was used to correct for extracellular space and to rule out leakages of medium between compartments. Lenses were paired in media with and without ouabain. In the absence of ouabain, 86Rb influx is greater at the anterior and equatorial surfaces than it is at the posterior surface. In the presence of ouabain, the differences in 86Rb influx are less pronounced. In the absence of ouabain, the net efflux of 86Rb at the anterior and equatorial surfaces, but not at the posterior surface, is less (P less than 0.01) than it is in the presence of ouabain. In the presence of ouabain, 86Rb efflux is the same at each of the surfaces. 86Rb efflux is not altered if the medium is changed every 30 min to decrease the uptake of isotope that is entering the medium while the efflux is being measured. 86Rb efflux is tripled in a Ca-free medium and the increase is limited to the surface that is exposed to the Ca-free medium. 22Na uptake from the posterior or anterior surface is the same in the presence or absence of ouabain. 22Na uptake from the anterior or the posterior surface results in an accumulation of 22Na in the equatorial chamber.(ABSTRACT TRUNCATED AT 250 WORDS)