Retinol and retinyl ester in separated structures of the guinea pig inner ear.

Chemical separation of different vitamin A derivates in inner ear extracts was performed by means of high pressure liquid chromatography (HPLC) with fluorescence and UV detection. For more accurate site identification the membranous cochlea was dissected and the basilar membrane, the spiral ligament and the stria vascularis were isolated for analysis. Retinyl esters were found in the basilar membrane at a concentration of 11.4 +/- 5.9 micrograms/g dry weight, a high concentration compared with that in other tissues of other organs. The spiral ligament contained retinyl esters at a lesser concentration and no retinyl esters were found in the stria vascularis. Retinol was not detected in the spiral ligament or basilar membrane but was found in the stria vascularis at a concentration of 1.2 +/- 0.8 micrograms/g. Retinyl palmitate and retinyl stearate were identified. This investigation shows that vitamin A forms retinyl esters with long-chain fatty acids in the basilar membrane in high concentrations relative to other organs and in greater quantity than in other sites in the inner ear.