Effect of l-dopa administration on rabbit lens and erythrocytes

Effect of feeding high dosage of l-dopa and a dopa decarboxylase inhibitor, l-isomer of α-hydrazino-α-(3,4-dihydroxybenzyl) propionic acid monohydrate, on the red blood cells and lens of rabbit eye was studied. The plasma l-dopa level increased after feeding l-dopa to rabbits. However, feeding dopa decarboxylase inhibitor along with l-dopa prolonged the persistence of high levels of l-dopa in plasma. Only very small amounts of l-dopa could be detected in the aqueous humor of rabbits fed l-dopa + inhibitor. Dopa decarboxylase activity was totally absent from the lens and was very slight in the red cells. l-Dopa alone or along with dopa decarboxylase inhibitor did not have any effect on the red cell survival in rabbits. Even 5 times the physiological level of plasma l-dopa found after feeding l-dopa + dopa decarboxylase inhibitor did not have any appreciable effect on red cell glutathione in vitro. Feeding l-dopa alone or l-dopa with dopa decarboxylase inhibitor has no cataractogenic effect.