Topic
Methyldopamine
About: Methyldopamine is a research topic. Over the lifetime, 16 publications have been published within this topic receiving 149 citations.
Papers
Journal Article•
TL;DR: The results suggested that the synthetic methyldopa was poorly transported by the alimentary and renal transport mechanisms normally available to amino acids, however l -methyldopawas found to be more readily absorbed from the gut than the d -isomer.
Abstract: The absorption, excretion, metabolism and effects on amino acid transport of l -methyldopa, d -methyldopa, dl -dopa, l -methyldopamine and dopamine have been studied in rats by means of paper chromatography of bile, plasma and urine. The results suggested that the synthetic methyldopa was poorly transported by the alimentary and renal transport mechanisms normally available to amino acids. However l -methyldopa was found to be more readily absorbed from the gut than the d -isomer. Methyldopa, dopa, and their corresponding amines were found to produce specific reversible amino acidurias involving histidine, taurine, serine, alanine, and glutamic acid most consistently. This was postulated to be the result of competition in the nephron for transport between the catechols and those amino acids believed to share the neutral transport system. After methyldopa therapy the main excretory product in the urine was the drug itself but small quantities of the 3-O-methyl derivative and very small amounts of methyldopamine and its 3-O-methyl derivative were also detected. Glucuronides of methoxymethyldopa and methoxymethyldopamine were also found in small amounts. When animals were given methyldopamine, dopa or dopamine the most prominent excretory products were glucuronides. d -Methyldopa was 3-O-methylated to give methoxymethyldopa but not decarboxylated to the amine. This was thought to be the reason for its therapeutic inactivity. Methyldopa and one metabolite thought to be a glucuronide derivative were excreted in the bile in small amounts relative to urinary concentrations of these substances. Effects on biliary amino acid patterns were slight.
28 citations
Journal Article•
TL;DR: This neuroendocrine model has alpha adrenergic receptor relationships analogous to those described in the central nervous system for methyldopa metabolites, and was not affected by pretreatment of frogs with the monoamine oxidase inhibitor pheniprazine nor by the application of phenipazine, angiotensin or serotonin in vitro.
Abstract: Catecholamines possessing alpha adrenergic receptor agonist properties induce lightening or reverse melanocyte stimulating hormone darkening of frog skin in vitro. The capacity to activate this alpha receptor by the methyldopa metabolites methyldopamine and methylnorepinephrine was compared with the capacity of the naturally occurring dopa metabolites, dopamine and norepinephrine. Melanocyte stimulating hormone-induced darkening or dispersion of the granules was reversed by each of these metabolites. Methylnorepinephrine was 10 times as potent as norepinephrine, and methyldopamine was 30- to 100-fold more potent than the naturally occurring dopamine. These inhibitory effects on melanocyte stimulating hormone could be blocked or partially impaired using the alpha adrenergic blocker, phentolamine. They were not affected by pretreatment of frogs with the monoamine oxidase inhibitor pheniprazine (Catron) nor by the application of pheniprazine, angiotensin or serotonin in vitro. This neuroendocrine model has alpha adrenergic receptor relationships analogous to those described in the central nervous system for methyldopa metabolites.
27 citations
TL;DR: Evaluation of (R)-(+)- and (S)-(-)-beta-methyldopamine revealed no enantioselectivity for stimulation of adenylate cyclase.
Abstract: beta-Methyldopamine and its enantiomers and racemic beta-phenyldopamine were synthesized and evaluated for dopamine D-1 agonist activity. In the dopamine-sensitive adenylate cyclase assay, beta-phenyldopamine had about one-sixth the activity of dopamine. Racemic beta-methyldopamine was less potent. The absolute configuration of beta-methyldopamine was determined to be R-(+) and S-(-). Evaluation of (R)-(+)- and (S)-(-)-beta-methyldopamine revealed no enantioselectivity for stimulation of adenylate cyclase.
18 citations
TL;DR: In this article, tritium-labeled (±)-a -methyldopamine was given i.v. to mice and converted to 3 H- a -methylnoradrenaline.
18 citations
TL;DR: The configuration of (−)-α-methyldopamine (IX; R = H) is related to that of d -(−)-alanine (VIII) by a series of reactions not involving the asymmetric center as discussed by the authors.
14 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2012 | 1 |
| 2006 | 1 |
| 1993 | 1 |
| 1989 | 1 |
| 1987 | 1 |
| 1983 | 1 |