Hexose monophosphate shunt in rat lens: stimulation by vitamin C.

The metabolism of glucose through the hexose monophosphate (HMP) shunt has been studied in rat lens in vitro, in the absence and presence of ascorbic and dehydroascorbic acids. Both forms of the vitamin stimulated the utilization of glucose through the HMP shunt, the stimulatory effect of dehydroascorbate being substantially greater than that of ascorbate. The stimulatory effect of ascorbate, as well as of dehydroascorbate, was antagonized by sodium iodide, and N,N-bis (dichloroethyl)-N-nitrosourea, compounds known to inhibit glutathione reductase. N-ethylmaleimide also antagonized the stimulation. These findings, therefore, suggest that the DHA/AA redox couple acts in concert with the GSSG/GSH couple in stimulating the tissue shunt activity.