EFFECTS OF l-DOPA ADMINISTRATION ON THE CONCENTRATIONS OF DOPA, DOPAMINE AND NOREPINEPHRINE IN VARIOUS RAT TISSUES

• Published in: The Journal of pharmacology and experimental therapeutics Vol. 184; no. 1; pp. 67 - 72
• Main Authors: Romero, J A, Lytle, L D, Ordonez, L A, Wurtman, R J
• Format: Journal Article
• Language: English
• Published: United States American Society for Pharmacology and Experimental Therapeutics 01.01.1973
• Subjects: Adrenal Glands - analysis; Animals; Dihydroxyphenylalanine - analysis; Dihydroxyphenylalanine - pharmacology; Dopamine - analysis; Epinephrine - analysis; Ferricyanides; Fluorescence; Kidney - analysis; Liver - analysis; Lung - analysis; Male; Muscles - analysis; Myocardium - analysis; Norepinephrine - analysis; Oxidation-Reduction; Rats; Spleen - analysis; Stomach - analysis; Time Factors
• ISSN: 0022-3565; 1521-0103

We have studied the effects of i.p. l -dopa on the concentrations of catechols in various rat tissues. Rats were killed at intervals after the last of 10 daily doses of l -dopa or its vehicle (0.05 N HCl); concentrations of dopa, dopamine and norepinephrine were measured in heart, lung, spleen, liver, kidney, striated muscle, stomach and adrenal glands. One hour after l -dopa administration, dopa was detectable in all tissues examined except liver; highest concentrations were found in muscle and spleen. Dopamine levels were also elevated in all tissues examined except lung. l -Dopa treatment caused small increases in norepinephrine concentrations of kidney, lung, muscle and liver; no change in spleen and stomach; and decreased levels in heart. Adrenal epinephrine levels were also depressed at 1, 3, 6 and 24 hours after the last l -dopa dose. Except for the adrenals, the changes in catecholamine levels in these tissues usually coincided with the presence of large amounts of dopa. Our data suggest that the major reservoir for free dopa after each dose of l -dopa is within skeletal muscle; in this sense, l -dopa behaves like any other aromatic l -amino acid. The capacity of a tissue to accumulate dopamine after l -dopa administration bears no obvious relationship to its normal catecholamine content and probably cannot be correlated with its density of sympathetic nerve endings or other cells that normally synthesize endogenous catecholamines.