| Abstract: | The ocular lens of the 28- to 32-day-old rat contains an active hexose monophosphate shunt pathway for the combustion of glucose. Triphosphopyridine nucleotide (TPNH) cytochrome c reductase is present in this organ and is approximately one-third more active than diphosphopyridine nucleotide (DPNH) cytochrome c reductase. Since there is no transhydrogenase activity in these lenses, and since DPNH lactic dehydrogenase is 15 times as active as TPNH lactic dehydrogenase, the presence of an active TPNH cytochrome c reductase may provide this organ with the means of reoxidizing the relatively large amounts of TPNH formed by the direct oxidative pathway of glucose metabolism. Although TPNH oxidation in other tissues has not as yet been shown to yield adenosine triphosphate (ATP) directly, it is possible that such a mechanism may be operative in the rat lens. |
