A modified relative dose-response assay employing 3,4-didehydroretinol (vitamin A2) in rats.
3,4-Didehydroretinol (vitamin A2, DR, dehydroretinol), a naturally occurring analogue of retinol (vitamin A1, R), is active in vision, growth and cellular differentiation but is converted to retinol in very small amounts, if at all. When vitamin A-depleted rats were given 500 micrograms of R acetate, a naturally occurring mixture of 480 micrograms DR ester and 20 micrograms R ester or 500 micrograms DR acetate orally in corn oil, serum levels of all administered retinoids peaked between 3.5 and 5 h and then declined. When an oral dose of 600 micrograms DR/kg body wt was administered to rats with various liver reserves of vitamin A, the serum ratio of DR to R at 3.5 h was inversely related to the liver reserves of vitamin A below approximately 2 micrograms/g liver. Because the administration of DR does not affect serum R values, a single blood sample taken at 3.5 h might provide information analogous to that obtained from two blood samples in the conventional relative dose-response method.
Tanumihardjo
S A
SA
Department of Biochemistry and Biophysics, Iowa State University, Ames 50011.
Olson
J A
JA
D000818:Animals; D002851:Chromatography, High Pressure Liquid; D005260:Female; D008099:Liver / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D014212:Tretinoin / Q000008:administration & dosage; D014801:Vitamin A / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood / Q000378:metabolism*; D014802:Vitamin A Deficiency / Q000378:metabolism*
C024366:vitamin A2; D014801:Vitamin A; D014212:Tretinoin