Response of plasma levels of vitamin A to a dose of vitamin A as an indicator of hepatic vitamin A reserves in rats
1979
Loerch, John D. | Underwood, Barbara A. | Lewis, Kevin C.
To determine the degree to which a relative dose response correlates with hepatic vitamin A stores over a range of plasma and liver vitamin A levels, rats were fed diets sufficient or deficient in vitamin A, and with or without retinoic acid supplementation, for up to 33 days. Rats with plasma vitamin A levels ranging from 7 to 62 micrograms/dl were studied at intervals during progressive depletion of liver stores of vitamin A and when liver stores were nearly exhausted or replete with vitamin A. A dose of retinyl acetate in corn oil was administered by intubation directly into the stomach. The relative dose response (RDR), expressed as a percentage and defined as absolute magnitude of the rise in plasma vitamin A levels 5 hours after the reginyl acetate, divided by plasma level of vitamin A after 5 hours, was determined for each rat. RDR above 50% was associated with low plasma levels and liver stores of vitamin A, whereas an RDR of less than 40% was associated with plasma levels above 30 micrograms/dl and liver stores ranging from 3 to 100 micrograms/g.
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