Abstract
The synthesis of "active sulfate" in rat liver was studied at various stages of vitamin A deficiency, with the corresponding pair-fed controls. The activity was significantly decreased even at the onset of the deficiency, and at the acute stage there was further loss. Only at the earlier stages of the deficiency was the addition of retinol, in vitro, fully effective in restoring the lost activity; retinoic acid was partially active. No such restoration was possible at the acute deficiency stage.