A simplified isotope dilution procedure for the assessment of vitamin A status in rats.

In four separate experiments, rats with liver reserves of vitamin A ranging from deficient to high were administered physiological doses (5, 10 or 20 micrograms) of [11,12-3H] retinol, either by gastric intubation or intraperitoneal injection, and sacrificed after either 7 days or 5 hours. Measurements were then made of radioactivity and vitamin A in plasma and liver. In all four experiments there was a highly significant negative correlation between the logarithm of the specific activity of plasma vitamin A and the logarithm of total liver vitamin A.