In vivo evidence for a differential contribution of striatal and nigral D1 and D2 receptors to l-DOPA induced dyskinesia and the accompanying surge of nigral amino acid levels

2012 ◽  
Vol 45 (1) ◽  
pp. 573-582 ◽  
Author(s):  
Flora Mela ◽  
Matteo Marti ◽  
Simone Bido ◽  
M. Angela Cenci ◽  
Michele Morari
Keyword(s):  
Amino Acid ◽  
D2 Receptors ◽  
D1 And D2 Receptors ◽  
Amino Acid Levels ◽  
Differential Contribution

Effect of free fatty acids on blood amino acid levels in human

1986 ◽  
Vol 250 (6) ◽  
pp. E686-E694 ◽  
Author(s):  
E. Ferrannini ◽  
E. J. Barrett ◽  
S. Bevilacqua ◽  
R. Jacob ◽  
M. Walesky ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Plasma Insulin ◽  
Plasma Free Fatty Acid ◽  
Blood Levels ◽  
Experimental Conditions ◽  
Lipid Infusion ◽  
Amino Acid Levels ◽  
Branched Chain

Raised plasma free fatty acid (FFA) levels effectively impede glucose uptake in vivo, thereby conserving plasma glucose and sparing glycogen. To test whether FFA have any effect on blood amino acid levels, we infused Intralipid plus heparin or saline into healthy volunteers under four different experimental conditions: A) overnight fast; B) euglycemic hyperinsulinemia (approximately 100 microU/ml); C) hyperglycemic (approximately 200 mg/100 ml) hyperinsulinemia (approximately 50 microU/ml); and D) hyperglycemic (approximately 300 mg/100 ml) normoinsulinemia (approximately 20 microU/ml). In the fasting state (A), lipid infusion was associated with lower blood levels of most amino acids, both branched chain and glucogenic. This effect, however, could not be ascribed to lipid infusion alone, because plasma insulin levels were also stimulated. The clamp studies (B, C, and D) allowed to assess the influence of lipid on blood amino acid levels at similar plasma insulin and glucose levels. It was thus observed that lipid infusion has a significant hypoaminoacidemic effect of its own under both euglycemic (B) and hyperglycemic (C) conditions; this effect involved many glucogenic amino acids (alanine, glycine, phenylalanine, serine, threonine, and cystine) but none of the branched-chain amino acids (leucine, isoleucine, and valine). In marked contrast, normoinsulinemic hyperglycemia (D), with or without lipid infusion, caused no change in the blood level of any measured amino acid. We conclude that lipid infusion has a hypoaminoacidemic action. We also suggest that this action is permitted by insulin and may involve specific metabolic interactions (e.g., reduced availability of glucose-derived pyruvate or glycerophosphate) as well as enhanced uptake by the liver.

In vivo blockade of thalamic GABAB receptors increases excitatory amino-acid levels

1996 ◽  
Vol 318 (2-3) ◽  
pp. 295-300 ◽  
Author(s):  
Gabriella Nyitrai ◽  
Zsuzsa Emri ◽  
Vincenzo Crunelli ◽  
Katalin A. Kékesi ◽  
Árpád Dobolyi ◽  
...  
Keyword(s):  
Amino Acid ◽  
Excitatory Amino Acid ◽  
Gabab Receptors ◽  
Amino Acid Levels

Effect of α2-adrenergic drugs dexmedetomidine and atipamezole on extracellular amino acid levels in vivo

1995 ◽  
Vol 285 (3) ◽  
pp. 239-246 ◽  
Author(s):  
Pirjo Valtonen ◽  
Antti Haapalinna ◽  
Paavo Riekkinen ◽  
Toivo Halonen
Keyword(s):  
Amino Acid ◽  
Adrenergic Drugs ◽  
Amino Acid Levels ◽  
Extracellular Amino Acid

Cerebral amino acid levels and uptake in rats after portocaval anastomosis: I. Regional studies in vivo

1979 ◽  
Vol 4 (4) ◽  
pp. 301-310 ◽  
Author(s):  
Giorgio Zanchin ◽  
Paolo Rigotti ◽  
Noemi Dussini ◽  
Paolo Vassanelli ◽  
Leontino Battistin
Keyword(s):  
Amino Acid ◽  
Regional Studies ◽  
Portocaval Anastomosis ◽  
Amino Acid Levels

Effect of acetyl-l-carnitine on extracellular amino acid levels in vivo in rat brain regions

1993 ◽  
Vol 18 (5) ◽  
pp. 573-578 ◽  
Author(s):  
E. Toth ◽  
L. G. Harsing ◽  
H. Sershen ◽  
M. T. Ramacci ◽  
A. Lajtha
Keyword(s):  
Amino Acid ◽  
Rat Brain ◽  
Brain Regions ◽  
Rat Brain Regions ◽  
Amino Acid Levels ◽  
Extracellular Amino Acid

Amino acid exchange between plasma and erythrocytes in vivo in humans

1989 ◽  
Vol 67 (6) ◽  
pp. 2383-2388 ◽  
Author(s):  
D. Darmaun ◽  
P. Froguel ◽  
M. Rongier ◽  
J. J. Robert
Keyword(s):  
Steady State ◽  
Amino Acid ◽  
Whole Blood ◽  
Gas Chromatography Mass Spectrometry ◽  
Confidence Limits ◽  
Amino Acid Exchange ◽  
High Concentration ◽  
Amino Acid Levels ◽  
Acid Exchange

To study amino acid exchange between plasma and erythrocytes in vivo, 4-h primed, continuous intravenous infusions of L-[1-13C]leucine, [15N]glycine, and L-[15N]alanine were administered to five healthy young men in the postabsorptive state. Stable isotope enrichments and amino acid levels were determined by gas chromatography-mass spectrometry in both plasma and whole blood and estimated (using hematocrit) in erythrocytes. A high concentration gradient across the erythrocyte membrane was consistently found for glycine (552 +/- 268 microM in erythrocytes vs. 155 +/- 35 microM in plasma), but not for leucine or alanine. A steady-state isotopic enrichment was observed in whole blood as well as plasma for each amino acid in every subject. Steady-state [13C]leucine enrichment in erythrocytes did not differ from plasma enrichment at steady state, the ratio of erythrocyte to plasma enrichment being 1.03 +/- 0.20 (95% confidence limits = 0.78-1.28); in contrast, this ratio reached only 0.23 +/- 0.04 and 0.59 +/- 0.09 (confidence limits 0.18-0.28 and 0.48-0.70) for [15N]glycine and [15N]alanine at steady state, respectively. These results suggest that most of erythrocyte leucine is exchangeable with plasma, whereas only a fraction of erythrocyte glycine and alanine is involved in exchange with plasma in vivo.

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