Vitamin A analogs as tests for liver vitamin A status in the rat.

Two chlorinated retinol analogs (Ro 11-0503 and Ro 11-8284) were assayed in rat serum and correlated to retinol in liver. Rats were fed a retinol-free diet to deplete their liver stores, then repleted with 0.5, 1.0, 3.0, and 10.0 mg retinyl palmitate/kg diet. Rats were given intraperitoneal injections of the analog then killed after an additional week on the diets. Analogs were measured by HPLC. The relative abundance of both analogs in serum was inversely correlated with the amount of retinyl palmitate in the liver. Serum analog concentrations may be useful as indications of liver retinol stores.