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Abstract
The characteristics of myoinositol transport in the lens were studied by culturing them in a medium containing the tritium-labeled compound. The accumulation in the lens takes place against a concentration gradient and is inhibited by ouabain, iodoacetate, phlorhizin, and at reduced temperature (Q10 = 3). The energy for transport is derived from glycolysis. The transport system follows Michaelis-Menten kinetics (Vmax = 0.02 µmoles per lens per hour, Km = 0.4 mM.) and requires the presence of Na+ and K+. Although a relationship between Na+ concentration and inositol transport was observed, the lenses in Na+ deficient media could not be maintained in a physiological state so that the decreased transport cannot be ascribed solely to the effect of this cation. Similar to the observations made in the ciliary body, the transport system in the lens is inhibited by inositol mono- and hexaphosphates and shows the same specificity for the stereoisomers of inositol. Unlike the findings in the case of ciliary body, inositol accumulation in lens is inhibited by several amino acids. The reciprocal inhibition of α-aminoisobutyric acid transport by inositol, however, could not be demonstrated.