Analysis of retinol and dideuterated retinol in rat plasma by gas chromatography combined mass spectrometry.

ABSTRACT

An isotope dilution method for determining the total body stores of vitamin A using a hydrocarbon derivative of rat plasma retinol, anhydroretinol (ANR) or dideuteroanhydroretinol (2H2ANR) has been evaluated by gas chromatography combined mass spectrometry (GC/MS). Rats with negligible vitamin A stores were dosed with retinyl acetate (ROA) or ROA and 11,12dideuteroretinyl acetate (2H2ROA). The 2H2ROA dose was allowed to equilibrate with total body stores for seven days and the deuterium/hydrogen ratio (D/H ratio) of rat plasma retinol fraction was determined. The results indicate that after the equilibration period the plasma D/H ratio is 73 to 108 percent of the loading dose D/H ratio. This study extends earlier reports that exogenous vitamin A storage is lower than the expected fifty percent figure in rats with low initial total body stores of vitamin A [1, 7, 8, 15, 17]. This work supports the concept that the estimation of total body stores of vitamin A by an isotope dilution method is useful for populations with negligible stores (i.e. liver stores) of vitamin A.