Free nucleosides and bases in the hyperkeratotic epidermis

The metabolism of both free nucleosides and bases in hyperkeratosis induced by topical application of n-hexadecane on the epidermis of guinea pig was discussed, based on the technique of high-pressure liquid chromatography. The level of nucleosides and bases decreased in the hyperkeratotic stage of epidermis, in spite of the high concentration of nucleotides. The concentration of purine bases in the epidermis was under the virtual control of the salvage enzyme pathway and uric acid formation. The significant increase of salvage enzyme activity with phosphoribosylation was responsible for the expansion of the purine nucleotide pool in the hyperkeratotic epidermis. It was noted that the increased nucleotide pool plays a role as a source of cellular energy and a precursor of nucleic acid for epidermal proliferation.