D-Alanine Is Reduced by Ocular Hypertension in the Rat Retina.

: The purpose of this study was to investigate the physiological changes of amino acids in the rat retina caused by ocular hypertension.: Adult Wistar rats were used as an experimental model of ocular hypertension. Retinas were hydrolyzed with HCl at 108°C to isolate amino acids. Residual amino acids were measured by reverse-phase high-performance liquid chromatography and the total volume of residual amino acids and the ratio of D- and L-amino acids were analyzed. Free D- and L-alanine levels were also measured using two-dimensional HPLC.: The amount of retinal alanine decreased in ocular hypertension compared with the control ( < .05, Student's -test); the amounts of other amino acids did not differ between the two conditions.The D/L ratio of alanine was higher than that of other amino acids. Ocular hypertension reduced the D/L ratio of retinal alanine, while that of other amino acids was unchanged. Ocular hypertension increased the D/L ratio of free alanine.: Ocular hypertension reduced the D/L ratio of retinal alanine, presumably due in large part to alanine peptides.