Effect of ethanol on plasma amino acids and related compounds of stressed male rats

Plasma amino acid levels in rats are known to be affected by ethanol or by immobilization stress. This paper investigated the effect of ethanol on plasma amino acid levels of stressed rats. Rats received ethanol (2 g/kg, IP) 15 minutes prior to a 30-min immobilization period. Blood samples were obtained from individual rats before, during and after stress. Ethanol lowered the concentration of most plasma amino acids (AA) or related compounds in stressed rats (e.g., aspartic acid, threonine, serine, glycine, alanine, valine, tyrosine, phenylalanine, tryptophan). Some compounds remained unaffected (e.g., taurine, cystine, ethanolamine and methylhistidines) and one (phosphoethanolamine) increased initially. A comparison of the effects of ethanol on plasma AA and related compounds in resting and stressed rats shows similarities and differences. In general, ethanol tends to change the concentrations of these compounds away from normal levels in nonstressed rats, whereas in stressed rats, ethanol tends to antagonize stress-induced changes. This study shows that ethanol can affect individual AA and related compounds differently in nonstressed and stressed rats and that ethanol reduces stress-induced changes. The latter finding supports the "tension-reduction hypothesis" of ethanol.     

血浆游离氨基酸的水平变化与高血压病的相关性

目的探讨血浆游离氨基酸变化与高血压的关系,指导治疗。方法用氨基酸分析仪对64例高血压患者及50名正常人血浆21种游离氨基酸进行检测,并用放射免疫法测定胰岛素、C肽、血脂及尿β2-MG。其中,有并发症患者(33例)为Ⅰa组,无并发症者(31例)为Ⅰb组。结果高血压患者血浆中游离氨基酸存在失衡,与正常人比较,必需氨基酸中缬、亮、异亮、苯丙、色氨酸升高,以Ⅰa组升高显著(P<0.01)。而非必需氨基酸除精、丙氨酸升高外,牛磺酸、谷、鸟、甘、丝、羟脯氨酸均低于正常人,尤以Ⅰb组下降显著(P<0.01、0.05)。氨基酸的变化与体重指数(BMI)及胰岛素、C肽、甘油三酯(TG)水平呈正相关(r=0.286、0.291、0.318、0.315),与尿中β2-MG、血糖、血压呈负相关(r=-0.413、-0.252、-0.318)。结论氨基酸失衡与高血压及其并发症关系密切。除低钠低胆固醇饮食外,高血压患者应调整其饮食结构,适当增加牛磺酸、叶酸的摄入,限制过多蛋白的摄入,尤其是同型半胱氨酸的前体物质蛋氨酸的摄入,对减轻体重,降低血压、血糖、血脂、抗脂质过氧化,预防动脉硬化均有益处。     

Effect of acute nitrogen dioxide exposure on the free amino acids of rat serum

Female Wistar rats were acutely exposed to 20 ppm nitrogen dioxide (NO₂). After 20 h exposure, the concentrations of valine, leucine, isoleucine and phenylalanine in serum significantly increased. Significant decreases were observed for aspartic acid, threonine, serine, glutamic acid, glycine alanine, cystine, methionine, tyrosine, lysine, arginine and proline. The concentrations of free amino acids of rats exposed to NO₂ for 40 h were close to the values for rats starved for 40 h.     

A STUDY ON THE STABILITY OF DIPHENYLINDENONESULPHONYL DERIVATIVES OF AMINO ACIDS TO ACID HYDROLYSIS

The stability of the diphenylindenonesulphonyl (disyl) derivatives of tryptophan, proline, hydroxyproline, histidine, serine, threonine and aspartic acid, as well as of glycine, alanine, α-amino butyric acid, phenylalanine, valine, leucine and isoleucine to acid hydrolysis is studied. The results indicate that the disyl derivatives are much more stable in comparison with the corresponding DNP-and DNS-derivatives. Hence, the dysil-chloride method possesses definite advantages over these widely used methods for determination of N-terminal groups, not only because of its higher sensitivity, but also because of the higher stability of the disyl derivatives of amino acids to acid hydrolysis.     

柱前衍生高效液相色谱法测定注射用骨肽中15种氨基酸含量

目的 建立测定注射用骨肽中15种氨基酸含量的柱前衍生高效液相色谱法.方法 色谱柱为Zorbax Eclipse AAA柱(150 mm×4.6 mm,5μm),衍生剂为邻苯二甲醛(自动衍生化进样程序),流动相A为40 mmol/L磷酸二氢钠溶液(pH 7.8),流动相B为乙腈-甲醇-水(45:45:10,V/V/V),...     

Effects of oral contraceptives on plasma neutral amino acids and cholesterol during a menstrual cycle

Objective: Concentrations of plasma neutral amino acids, i.e. threonine, serine, asparagine, glycine, alanine, citrulline, α-aminobutyric acid, valine, methionine, isoleucine, leucine, tyrosine, phenylalanine, and tryptophan, and serum cholesterol, were determined at the follicular (Day 4), mid-cycle (Day 16) and luteal (Day 25) phases of the menstrual cycle in 15 users of the new generation of combined oral contraceptives (OC), 11 on multiphase combined OC, and 17 controls. Results: The controls showed a decrease in the sum of amino acids to 95% at mid-cycle and 90% in the luteal phase relative to the follicular phase, and a significant decrease in the tyrosine level at the luteal relative to the follicular phase. Since there was no significant difference between the two OC subgroups in the levels of the specified variables at either of the phases, the two groups were considered together. The sum of amino acids in the OC group decreased to 89% at mid-cycle and 91% at the luteal phase relative to the follicular phase, indicating less metabolic effect than reported for older OC formulations. Compared to the controls, the OC group showed significant increased threonine level at the luteal phase, decreased glycine levels at mid-cycle and the luteal phases, decreased citrulline level at mid-cycle, and markedly decreased tyrosine levels at the mid-cycle and luteal phases. Neither total nor high density lipoprotein (HDL) cholesterol differed significantly between the control and OC groups. Conclusion: The results suggest that the metabolic effects of the new generation combined OC on neutral amino acids and cholesterol are only modest to slight, except for the effect on tyrosine, the brain noradrenaline precursor, which may cause disturbances of various noradrenaline-mediated central functions in susceptible subjects.     

Genotoxicity of chlorine-treated amino acids

Chlorine treatment, a commonly used disinfection procedure, was found to produce genotoxic amino acid derivatives. The umu testing using Salmonella typhimurium TA1535/pSK1002 carrying the umuC-lacZ fusion gene, in which genotoxicity can be detected in terms of β-galactosidase activity, was used to examine chlorine-treated amino acids. Ten of the 14 L -amino acids tested (arginine, glycine, histidine, hydroxyproline, lysine, methionine, phenylalanine, proline, serine, threonine) showed genotoxicity after reaction with chlorine, while alanine, isoleucine, leucine, and valine did not. © 1993 John Wiley & Sons, Inc.     

The effect of o,p'-DDT feeding and food deprivation on plasma and liver amino acids and liver serine dehydratase in rats

The effect of DDT feeding and food deprivation on liver and plasma amino acid concentrations was studied. DDT feeding had no effect on plasma amino acids but resulted in an increase in the concentration of liver isoleucine, ornithine, phenylalanine, serine, and threonine. In rats that were fed the control or DDT for 2 weeks and then deprived of food for 48 hr, the concentrations of liver isoleucine, phenylalanine, serine, and threonine were similar. The activity of liver serine dehydratase was decreased in hepatocytes from DDT-fed rats compared to fed controls. After food deprivation, the activity of serine dehydratase was similar in hepatocytes from control and DDT-fed rats, which is consistent with the response of liver serine and threonine concentrations to DDT feeding. Gluconeogenesis from serine was determined in isolated hepatocytes from DDT and control-fed rats and it was found that rates of gluconeogenesis were not affected by DDT feeding. This would indicate that the activity of serine dehydratase is not limiting for gluconeogenesis from serine in hepatocytes from fed rats.     

Amino acid tolerance in cirrhotic patients following oral protein and amino acid loads

Plasma amino acid and venous blood ammonia concentrations were measured in six patients with well-compensated cirrhosis and in six healthy volunteers, both in the fasting state and serially for 5 h following ingestion of 30 g mixed protein and 30 g amino acid mixture, administered on separate occasions. Mean fasting plasma concentrations of threonine, serine, proline, glycine, and of the three branched-chain amino acids, valine, isoleucine and leucine, were significantly reduced in the cirrhotic patients compared with the control subjects, while mean (+/- 1 s.d.) fasting venous blood ammonia concentrations were comparable 71.2 +/- 31.4 cf. 56.0 +/- 25.4 mumol/L. Following the oral protein and amino acid loads, increases were observed in plasma amino acid concentrations in the majority of subjects with a return to baseline values by the end of the study. Changes in the circulating concentrations of most amino acids were independent of their concentration in the oral protein and amino acid loads, and their relative distribution in the circulation varied over time. The increases in the concentrations of the three branched-chain amino acids did, however, reflect their concentrations in the two nitrogen loads and did remain constant, relative to one another, over time. There were wide intra- and inter-individual variations in plasma amino acid concentrations following protein and amino acid ingestion in both study groups, and in general no significant differences in responses were observed between them. Similarly, no significant inter-group differences were observed in the ammonia response to the two nitrogen loads. No fundamental differences exist in the ways in which patients with well-compensated cirrhosis handle oral protein or amino acid loads of the magnitude employed in the present study.     

Milacemide effects on the temporal inter-relationship of amino acids and monoamine metabolites in rat cerebrospinal fluid

The temporal inter-relationship of various amino acids and monoamine metabolites in rat cerebrospinal fluid was examined after acute administration of milacemide (100, 200 or 400 mg/kg i.p.), a glycine prodrug. Glycine concentrations rose linearly and dose dependently (20–190%) but were only significantly elevated at the higher milacemide dose (200 and 400 mg/kg). In animals given 400 mg/kg, glycine values were still significantly elevated 8 h later. A concomitant increase (20–25%) in serine and taurine and a decrease in alanine cerebrospinal fluid values were observed at the highest milacemide dose. Other amino acids were unaffected. While cerebrospinal fluid 5-hydroxyindoleacetic acid concentrations were unaffected, the dopamine metabolites, 3,4-dihydroxyphenylacetic acid and homovanillic acid, exhibited a linear dose-dependent reduction. However, only homovanillic acid values were significantly decreased after 400 mg/kg milacemide. Cerebrospinal fluid analysis may be useful as a first screen in ascertaining putative neurochemical changes associated with drug administration.