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PubMed1991

The influence of branched chain amino acids on colonic atrophy and anastomotic strength in the rat.

Conventional solutions of parenteral nutrients fail to reverse the colonic atrophy caused by starvation. This may be due to the absence from these solutions of the amino acid glutamine--a fuel for rapidly dividing cells such as colonocytes and fibroblasts. Although glutamine is unstable in solution, the infusion of branched chain amino acids (BCAA) increases the rate of synthesis and release of glutamine from skeletal muscle. We evaluated the hypothesis that the infusion of BCAA into undernourished rats would reduce the extent of mucosal atrophy and enhance the healing of anastomoses in the colon. Undernourished rats were randomized to receive 6 days of either a normal diet (Chow), conventional parenteral nutrition (CPN), or CPN supplemented with 1.8% BCAA (BCAA). The BCAA group had a higher plasma glutamine concentration than the Chow group (P less than 0.05). Compared with the CPN group, the BCAA group had the greater colonic mucosal weight (P less than 0.05) and colonic mucosal protein content (P less than 0.05), but there were no significant differences between groups in the bursting wall tension of the colon or the hydroxyproline content of the anastomoses. Although the infusion of BCAA has a beneficial effect on colonic atrophy, this did not result in the more secure healing of colonic anastomoses in this experimental model.

Amino Acids↗
PubMed1987

The partial protective effect of branched chain amino acids against streptozotocin-induced cytotoxicity to mouse pancreatic islets in vitro.

Recent experiments suggested that injections of branched chain amino acids (BCAA) immediately followed by streptozotocin (SZ), induced a partial protection against the diabetogenic action of SZ in vivo. In the present investigation, isolated mouse pancreatic islets were exposed in vitro to SZ (2.2-4.4 mM), with or without preincubation in a mixture of BCAA (15 mM leucine, 15 mM isoleucine and 15 mM valine). In order to evaluate the toxic action of SZ on the beta-cell, the islets were studies after culture for 3 days following SZ exposure. In control islets which had not been pretreated with BCAA, 4.4 mM SZ induced a 47% diminution in the islet number, while only 20% were lost after pretreatment with BCAA. There was also a greater total islet DNA content recovered in the islets pretreated with BCAA before SZ exposure. The BCAA islets furthermore maintained a slightly higher insulin release to the culture medium, insulin content and insulin response to an acute glucose stimulus. Preincubation with each of the amino acids alone did not protect against the SZ action. The present data are consistent with previous in vivo findings and suggest that a direct BCAA-induced decrease in the beta-cell sensitivity to SZ can explain the partial protective effect of these amino acids against the diabetogenic action of SZ.

Amino Acids, Branched-Chain↗
PubMed1996

Branched-chain amino acid supplementation during repeated prolonged skiing exercises at altitude.

This study was conducted to test the hypothesis that a branched-chain amino acid (BCAA) supplementation would minimize changes in body composition and alterations in plasma amino acid profile induced by prolonged exercises at altitude. Twenty-four highly trained subjects participated in six successive sessions of ski mountaineering (6-8 hr duration, altitude 2,500-4,100 m). Twelve subjects took a dietary supplement of BCAA (BCAA group) and 12 took a dietary supplement that was 98% carbohydrate (C group). Body weight decreased in C subjects (-2.1%, p < .01), while the body weight loss recorded in the BCAA group was not statistically significant (-1.2%, NS). Changes in body composition that resulted from repeated skiing exercise at altitude were not significantly minimized by BCAA administration. Peak power output recorded during an incremental bicycle exercise decreased in C subjects but did not change significantly in BCAA subjects. Results of this study demonstrate that neither changes in body composition related to the ski mountaineering program nor muscular performance during isometric contraction was significantly affected by BCAA administration.

Adult↗
PubMed1988

Effects of diabetes and starvation on skeletal muscle branched-chain alpha-keto acid dehydrogenase activity.

The activation state of branched-chain alpha-keto acid dehydrogenase (BCDH) was studied in rat hindlimb muscles during starvation and insulinopenic diabetes, conditions in which circulating branched-chain amino acids (BCAA) are increased and their oxidation is accelerated. Muscle BCDH is predominantly inactive (phosphorylated) in postabsorptive rats but is activated by increased circulating leucine. Diabetes (streptozotocin-induced and spontaneous BB/W) increased circulating BCAA four- to fivefold and BCDH activity approximately threefold. Insulin treatment caused near normalization of circulating BCAA without correcting BCDH activity. Adrenalectomy of diabetics decreased (without normalizing) circulating BCAA and BCDH activation. Starvation caused mild, progressive increases in circulating BCAA and significant activation of BCDH only after 4 days. Leucine infusion activated BCDH in muscle but the activation by leucine was markedly blunted by diabetes. In isolated perfused hindlimbs (control and diabetic) insulin did not affect BCDH significantly; perfusion with leucine activated BCDH, and this response appeared blunted in diabetics. Activation of muscle BCDH may contribute to increased BCAA catabolism in diabetes; the blunted activation response to hyperleucinemia may spare BCAA and contribute to their persistent elevation in plasma.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
PubMed1999

Low glycogen and branched-chain amino acid ingestion do not impair anaplerosis during exercise in humans.

We examined the hypothesis that increasing the rate of branched-chain amino acid (BCAA) oxidation, during conditions of low glycogen availability, reduces the level of muscle tricarboxylic acid cycle intermediates (TCAI) by placing a carbon "drain" on the cycle at the level of 2-oxoglutarate. Six men cycled at approximately 70% of maximal oxygen uptake for 15 min under two conditions: 1) low preexercise muscle glycogen (placebo) and 2) low glycogen combined with BCAA ingestion. We have previously shown that BCAA ingestion increased the activity of branched-chain oxoacid dehydrogenase, the rate-limiting enzyme for BCAA oxidation in muscle, compared with low glycogen alone [M. L. Jackman, M. J. Gibala, E. Hultman, and T. E. Graham. Am. J. Physiol. 272 (Endocrinol. Metab. 35): E233-E238, 1997]. Muscle glycogen concentration was 185 +/- 22 and 206 +/- 22 mmol/kg dry wt at rest for the placebo and BCAA-supplemented trials, respectively, and decreased to 109 +/- 18 and 96 +/- 10 mmol/kg dry wt after exercise. The net increase in the total concentration of six measured TCAI ( approximately 95% of TCAI pool) during exercise was not different between trials (3.97 +/- 0. 34 vs. 3.88 +/- 0.34 mmol/kg dry wt for the placebo and BCAA trials, respectively). Muscle 2-oxoglutarate concentration decreased from approximately 0.05 at rest to approximately 0.03 mmol/kg dry wt after exercise in both trials. The magnitude of TCAI pool expansion in both trials was similar to that seen previously in subjects who performed an identical exercise bout after a normal mixed diet [M. J. Gibala, M. A. Tarnopolsky, and T. E. Graham. Am. J. Physiol. 272 (Endocrinol. Metab. 35): E239-E244, 1997]. These data suggest that increasing the rate of BCAA oxidation has no measurable effect on muscle TCAI during exercise with low glycogen in humans. Moreover, it appears that low resting glycogen per se does not impair the increase in TCAI during moderate exercise.

Adult↗
PubMed1985

Regulation of myocardial amino acid balance in the conscious dog.

The effects in vivo of physiologic increases in insulin and amino acids on myocardial amino acid balance were evaluated in conscious dogs. Arterial and coronary sinus concentrations of amino acids and coronary blood flow were measured during a 30-min basal and a 100-min experimental period employing three protocols: euglycemic insulin clamp (plasma insulin equaled 70 +/- 11 microU/ml, n = 6); euglycemic insulin clamp during amino acid infusion (plasma insulin equaled 89 +/- 12 microU/ml, n = 6); and suppression of insulin with somatostatin during amino acid infusion (plasma insulin equaled 15 +/- 4 microU/ml, n = 6). Basally, only leucine and isoleucine were removed significantly by myocardium (net branched chain amino acid [BCAA] uptake equaled 0.5 +/- 0.2 mumol/min), while glycine, alanine, and glutamine were released. Glutamine demonstrated the highest net myocardial production (1.6 +/- 0.2 mumol/min). No net exchange was seen for valine, phenylalanine, tyrosine, cysteine, methionine, glutamate, asparagine, serine, threonine, taurine, and aspartate. In group I, hyperinsulinemia caused a decline of all plasma amino acids except alanine; alanine balance switched from release to an uptake of 0.6 +/- 0.4 mumol/min (P less than 0.05), while the myocardial balance of other amino acids was unchanged. In group II, amino acid concentrations rose, and were accompanied by a marked rise in myocardial BCAA uptake (0.4 +/- 0.1-2.6 +/- 0.3 mumol/min, P less than 0.001). Uptake of alanine was again stimulated (0.9 +/- 0.3 mumol/min, P less than 0.01), while glutamine production was unchanged (1.3 +/- 0.4 vs. 1.6 +/- 0.3 mumol/min). In group III, there was a 4-5-fold increase in the plasma concentration of the infused amino acids, accompanied by marked stimulation in uptake of only BCAA (6.8 +/- 0.7 mumol/min). Myocardial glutamine production was unchanged (1.9 +/- 0.4-1.3 +/- 0.7 mumol/min). Within the three experimental groups there were highly significant linear correlations between myocardial uptake and arterial concentration of leucine, isoleucine, valine, and total BCAA (r = 0.98, 0.98, 0.92, and 0.97, respectively); P less than 0.001 for each). In vivo, BCAA are the principal amino acids taken up by the myocardium basally and during amino acid infusion. Plasma BCAA concentration and not insulin determines the rate of myocardial BCAA uptake. Insulin stimulates myocardial alanine uptake. Neither insulin nor amino acid infusion alters myocardial glutamine release.

Amino Acids↗
PubMed1991

Myocardial protein turnover in patients with coronary artery disease. Effect of branched chain amino acid infusion.

The regulation of protein metabolism in the human heart has not previously been studied. In 10 postabsorptive patients with coronary artery disease, heart protein synthesis and degradation were estimated simultaneously from the extraction of intravenously infused L-[ring-2,6-3H]phenylalanine (PHE) and the dilution of its specific activity across the heart at isotopic steady state. We subsequently examined the effect of branched chain amino acid (BCAA) infusion on heart protein turnover and on the myocardial balance of amino acids and branched chain ketoacids (BCKA) in these patients. In the postabsorptive state, there was a net release of phenylalanine (arterial-cardiac venous [PHE] = -1.71 +/- 0.32 nmol/ml, P less than 0.001; balance = -116 +/- 21 nmol PHE/min, P less than 0.001), reflecting protein degradation (142 +/- 40 nmol PHE/min) in excess of synthesis (24 +/- 42 nmol PHE/min) and net myocardial protein catabolism. During BCAA infusion, protein synthesis increased to equal the degradation rate (106 +/- 24 and 106 +/- 28 nmol PHE/min, respectively) and the phenylalanine balance shifted (P = 0.01) from negative to neutral (arterial-cardiac venous [PHE] = 0.07 +/- 0.36 nmol/ml; balance = 2 +/- 25 nmol PHE/min). BCAA infusion stimulated the myocardial uptake of both BCAA (P less than 0.005) and their ketoacid conjugates (P less than 0.001) in proportion to their circulating concentrations. Net uptake of the BCAA greatly exceeded that of other essential amino acids suggesting a role for BCAA and BCKA as metabolic fuels. Plasma insulin levels, cardiac double product, coronary blood flow, and myocardial oxygen consumption were unchanged. These results demonstrate that the myocardium of postabsorptive humans is in negative protein balance and indicate a primary anabolic effect of BCAA on the human heart.

Aged↗
PubMedDate not supplied

High-branched chain amino acid solutions: relationship of composition to efficacy.

A prospective clinical trial was undertaken to determine the nitrogen-sparing efficacy of three amino acid solutions with different concentrations of branched-chain amino acids (BCAA) in 25 postoperative patients. The patients were a homogenous male population with stage I bladder cancer who underwent radical cystectomy. Administration rates of the intravenous solutions were designed to provide 30 kcal/kg/day and 1.5 g protein per kg per day during the 7-day study period. A control group (n = 4) received 5% dextrose in water (150 g/day). Nitrogen balance was determined daily and the whole body protein turnover was measured using a primed-constant infusion of 15N glycine on postoperative days 3 and 4. The group receiving the 45% BCAA enriched (low leucine) amino acid solution exhibited a significant decrease in cumulative (7 day) nitrogen balance (7.6 +/- 2.6 g) compared to the groups receiving either the standard 25% BCAA (19.9 +/- 2.1 g) or the 45% BCAA enriched (high leucine) (21.6 +/- 7.0 g) amino acid solution. The group receiving the 45% BCAA enriched (low leucine) amino acid solution exhibited a higher rate of mean whole body protein catabolism compared to the other groups. For patients undergoing major elective operations, the amount of leucine necessary for optimal daily nitrogen balance was 0.13 g/kg/day. These results demonstrate that the ratio of individual BCAA and the amount of leucine were more critical to nitrogen-sparing efficacy than the percentage total BCAA infused.

Aged↗
PubMedDate not supplied

Standard or branched-chain amino acid infusions as short-term nutritional support in liver cirrhosis?

The metabolic effects of selected and branched-chain amino acid (BCAA)-enriched parenteral solutions were studied in liver cirrhosis. After 3 days of an oral protein-free diet with balanced amino acid (AA) infusion, 36 cirrhotic patients without encephalopathy were randomly divided into four groups. Groups A and B were infused for 5 days with BCAA (valine, leucine, isoleucine) at doses of 0.5 and 1.0 g/kg/day, respectively, as the only nitrogen source. Group C received 0.8 g/kg of essential and nonessential AA solution with a prevalence of BCAA; the last group (D) continued the basic standard diet, as control. Routine chemistry, urinary nitrogen losses, nitrogen balance, and the whole plasma AA pattern were detected before and after the treatment period. BCAA alone led to an impressive and significant improvement in the basic AA pattern in both the A and B groups. The same results were obtained in group C for plasma AA. In particular, the ratio of BCAA to aromatic amino acids in groups A, B, and C was significantly increased (p less than 0.01, less than 0.02, less than 0.02, respectively). In group D the AA pattern and the BCAA/aromatic amino acid ratio remained unchanged. The negative nitrogen balance of the base state remained unchanged after 0.5 g of BCAA (A); it improved significantly and became positive during and after the infusions of a double dose of BCAA (B), as it did in the case of selective solutions (C), although to a lesser extent; the negative nitrogen balance of the control group showed only a slight improvement.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1987

Branched-chain amino acid carbon and nitrogen arteriovenous concentration differences across the ovine fetal hindlimb.

During fasting, branched-chain amino acids (BCAA) are thought to be major sources of nitrogen for myocyte synthesis of alanine (Ala) and glutamine (Gln), as well as possible sources of carbon skeleton for Gln synthesis. To study the relationships between Ala, Gln, and BCAA, we utilized the chronic fetal lamb preparation and measured arteriovenous concentration differences of Ala, Gln, BCAA, and branched-chain alpha-keto acids across the fetal hindlimb. Studies were performed when the ewe was fed and repeated after 1 and 5 days of complete maternal fasting. Ala and Gln are released from fetal hindquarters during fasting (arteriovenous -9.6 +/- 5 and -8.8 +/- 4.1 mumol/liter), while arteriovenous differences for BCAA simultaneously increase by 65% as compared to the fed state. During fasting, total nitrogen exiting fetal hindlimb as Ala and Gln equals nitrogen entering as BCAA. Branched-chain alpha-keto acids are released from fetal hindquarters during the fed state as well as after 1 day of fasting; at 5 days of fasting only keto-isovalerate had a net negative arteriovenous difference. In all cases, the release was much smaller than the entry of the corresponding amino acid, as determined by simultaneously measured arteriovenous concentration differences. These results indicate: Ala and Gln are released from fetal hindlimb, as in postnatal animals, during fasting, shuttling nitrogen and carbon to liver and/or other tissues. There is negligible movement of BCAA carbon as the branched-chain alpha-keto acids from hindlimb to other tissues in the fetus. BCAA carbon taken up is utilized within the hindquarters. It may be used for tissue synthesis, as an energy source, or possibly for Gln synthesis.

Amino Acids, Branched-Chain↗
PubMed1984

Effects of branched chain amino acids on spontaneous growth hormone secretion in the baboon.

Blood concentrations of the branched chain amino acids (BCAAs) are elevated during fasting in healthy subjects and are abnormally high both postprandially and during fasting in diabetic patients. Despite evidence that these amino acids influence brain metabolism and neurotransmitter synthesis, there is little information on the neuroendocrine effects of the BCAAs. This study provides evidence that elevation of postprandial blood levels of the BCAAs alters the ultradian rhythm of GH secretion observed in the baboon during daylight hours. To mimic the postprandial rise in the BCAAs that occurs in diabetic patients, we infused either saline or a mixture of valine, leucine, and isoleucine into six conscious male baboons from 1530-1900 h daily for 4 days during and after the normal feeding time. On the last day of the infusions, blood samples were collected at 20-min intervals from 0800-1500 h and at 30-min intervals from 1500-2000 h. The amino acid infusions increased postprandial blood concentrations of the BCAAs 2- to 5-fold over control levels and lowered the blood concentrations of tyrosine, phenylalanine, and lysine compared to concentrations observed during control infusions. A significant elevation in GH levels occurred in association with BCAA treatment in each animal between 0800 and 1100 h, 13 h after the previous day's infusion. Average +/- SE maximum GH levels observed between 0800 and 1100 h were 11.6 +/- 2.9 ng/ml under experimental conditions compared to a control value of 3.8 +/- 1.2 (P less than 0.02). Whether the increased GH levels represented the generation of a new peak or a phase shift in a nocturnal peak was not determined. Combined with evidence that spontaneous release of GH is neurally regulated in the baboon, this study suggests that changes in the blood levels of the BCAAs modulate neural mechanisms that regulate GH rhythmicity.

Amino Acids, Branched-Chain↗
PubMed1999

Evaluating response to nutritional therapy using the branched-chain amino acid/tyrosine ratio in patients with chronic liver disease.

The branched-chain amino acid (BCAA)/tyrosine (Tyr) ratio (BTR) recently has been reported to be a good indicator of the severity of hepatic parenchymal injury in patients with chronic liver disease. In the present study, sequential changes of BTR after BCAA administration were determined in patients with chronic liver disease to evaluate the value of BTR as a marker of the clinical response to nutritional therapy in these patients. This study comprised 75 patients with chronic hepatitis and 96 with liver cirrhosis. BTR was significantly decreased in patients with cirrhosis and hepatitis compared with healthy subjects. BTR was significantly correlated with the Child-Pugh score and with other liver function tests. BCAA increased significantly 2 hr after BCAA administration and decreased gradually thereafter. Tyr significantly decreased 4 hr after BCAA administration. BTR significantly increased 2 and 4 hr after BCAA therapy. The increase in BTR 3 hr after BCAA administration was low in patients with decreased basal BTR. The results of this study showed that BTR is a good index of the hepatic parenchymal damage and that it may be a useful marker for monitoring response to nutritional therapy in patients with chronic liver disease.

Amino Acids, Branched-Chain↗
PubMed2001

Branched-chain aminoacids and retraining of patients with chronic obstructive lung disease.

BACKGROUND: The aim of this work was to improve the efficacy of rehabilitation by retraining, by oral supply in branched-chain aminoacids (BCAA). Patients with chronic respiratory insufficiency mainly suffer from obstructive bronchitis due to tobacco or asthma. Nutritional assessment is one of the components of respiratory rehabilitation, with retraining. Intense physical training for several days negativates the nitrogen balance, the beginning of a training programme for sedentary patients increases their need in proteins. An additional supply in branched-chain aminoacids increases proteic anabolism, by synthesis increase and catabolism slackening of proteins. Moreover it is known that exposure to high altitude reduces lean mass by inducing a muscular atrophy, which can be avoided by the BCAA provided. This leads to wonder if extra supply of BCAA could play similar role in muscular mass loss induced by pathological chronic hypoxia. METHODS: The prospective and comparative survey carried out in Toki-Eder (private hospital in Cambo) consisted in supplying (during five weeks or more) 30 retrained patients suffering from chronic obstructive bronchitis, and in matching them with 30 witnesses (obstructive patients retrained without additional supply in BCAA). Their mean hypoxemia amounted to 7 torr for age. RESULTS: Each of them improved their reached maximal power, and their VO2 SL, very highly significantly. Each of them developed a moderate metabolic acidosis (whose possible mechanisms are discussed) and slightly increased their ventilation at rest. On the other hand only the supplied patients improved their PaO2 at rest highly significantly, a result which poses the question of the responsible mechanism, most likely a decrease of pulmonary shunt effect. The hypotheses concerning the acid load due to BCAA ingestion are discussed. Only the supplied patients developed hypocapnia expressing a gaseous alkalosis which might be due to a direct effect of BCAA on the respiratory centers. CONCLUSIONS: This observation could have practical outcomes in the management of rehabilitation of chronic respiratory insufficiency: it should be useful to systematically supplement the patients with BCAA during their retraining in order to obtain a more effective improvement of their respiratory function.

Amino Acids, Branched-Chain↗
PubMed2005

[Glutamine and branched-chain amino acids--practical importance of their metabolic relations].

Branched-chain amino acids (BCAAs; valine, leucine, and isoleucine) represent important precursors in the synthesis of glutamine and alanine in the skeletal muscle. Enhanced oxidation of BCAAs can cover the elevated demands of the body on glutamine and alanine during severe illnesses (sepsis, polytrauma, burns). The sufficient supply of the BCAAs in such conditions is facilitated by increased proteolysis in skeletal muscle. However, it can result in muscle wasting and negative protein balance. While concentrations of the BCAAs and alanine are rarely significantly altered, a marked decrease in glutamine concentration, particularly in skeletal muscle, is frequently observed. Glutamine is therefore considered to be a conditional essential amino acid. The manuscript describes the metabolic relations between BCAAs and glutamine, and explains the importance of the recycling of BCAAs and their ketoanalogues between the liver and skeletal muscle. Finally, it is suggested that the favourable effect of glutamine administration on protein metabolism is related to changes in BCAA metabolism.

Amino Acids, Branched-Chain↗
PubMed1997

[The branched-chain amino acids].

Branched-chain amino acids (BCAA: leucine, isoleucine and valine) are not just structural constituents of proteins, but have ''pharmacologic'' properties, known for several years: BCAA are catabolized mainly in muscle; can be oxidized with energy production, being nitrogen donors for other amino acids; regulate protein synthesis and degradation; modulate metabolism of neuroactive mediators. These properties make the clinical use of BCAA particularly suitable in critical conditions such as liver cirrhosis, sepsis, surgical or nonsurgical trauma, acute renal failure, acute pancreatitis, cancer, in which energy production from conventional substrates is altered and, at the same time, reduction of protein catabolism and enhancement of synthetic processes is advisable. Recently, the changes of plasma aminoacidograms induced by the administration of high-dose BCAA in sepsis have been better detailed: 1) a tendency to normalization of high levels of proline and of other amino acids transported intracellularly by transport system ''A''; 2) less relevant reduction of the levels of other amino acids; 3) increase of the levels of taurine, glutamate and aspartate; more complex interactions with specific amino acids. These changes, and changes of other variables, reconfirm in part some well-known properties of BCAA, and are also objective indicators of an improvement of the metabolic abnormalities of sepsis induced by BCAA administration. In sepsis and in other stress conditions it is recommended to administer, within balanced parenteral nutritional regimens, AA solutions with a 35-50% BCAA concentration.

English Abstract↗
PubMed1989

[The effect of enriched branched chain amino acid solution on amino acid metabolism during perioperative total parenteral nutrition support].

A prospective, randomized clinical study was performed in patients underwent subtotal gastrectomy or hemicolectomy. Patients were randomly divided into two groups receiving standard amino acid solution (23% BCAA) or a solution enriched with branched chain amino acid (41% BCAA). Preoperative postprandial plasma amino acid levels were used as base line. The amino acid concentrations in plasma between control group (A) and study group (B) were compared during perioperative period. The dynamics of postoperative plasma amino acid profile of the two groups were similar except that plasma BCAA concentrations were very high in group B. In both groups, the levels of plasma glutamine, alanine, tyrosine, lysine, threonine, arginine, asparagine, and cystine decreased, whereas the levels of plasma methionine, phenylalanine, and tryptophan increased. The solution of 41% BCAA was not found to be superior to standard 23% BCAA in normalizing the disorder of plasma amino acid spectrum during the period of TPN support. The differences of urinary amino acid excretion including 3-MHIS and nitrogen balance between the two groups were not statistically significant. Also the results showed more severe disorder of plasma amino acid profile caused by 41% BCAA solution than by standard solution of 23% BCAA.

Adult↗
PubMed1981

Nitrogen-sparing mechanisms of singly administered branched-chain amino acids in the injured rat.

Previous studies have demonstrated that the in vivo nitrogen-conserving quality of amino acid solutions might be improved by increasing the percentage of branched-chain amino acids (BCAA) and that infusion of a solution consisting only of the three BCAA-valine, leucine, and isoleucine-in the postoperative period resulted in nitrogen equilibrium. To clarify which of the properties ascribed to the BCAA is responsible for the improved postoperative nitrogen conserving quality, we infused rats undergoing laparotomy and jugular vein cannulation with each of the BCAA or alanine separately. Twenty-four hours before the were killed 5 microCi 14C-tyrosine was added to the infusate to determine total body protein degradation and fractional synthesis rate in liver and muscle. All four amino acid-containing solutions conserved nitrogen as compared with 6.5% dextrose. Fractional synthesis of rate mixed liver protein was significantly increased in all groups receiving BCAA. Only the infusion of valine significantly increased muscle protein synthesis. Total body protein breakdown rate was similarly decreased in all groups receiving amino acids (alanine, valine, leucine, or isoleucine). Total body protein breakdown correlated significantly with the nitrogen balance. The protein-sparing mechanisms of the BCAA in the post-traumatic period are mediated through reduction in whole body protein breakdown, as well as by increasing protein synthesis in both liver and muscle protein. These results appear specific for the BCAA as isonitrogenous amounts of alanine do not give similar results.

Alanine↗
PubMedDate not supplied

Branched-chain amino acid supplementation during 30-km competitive run: mood and cognitive performance.

It has been suggested that an elevated concentration of the neurotransmitter serotonin (5-hydroxytryptamine, 5-HT) in specific areas of the brain may contribute to the development of central/mental fatigue during and after sustained exercise. Supplementation with branched-chain amino acids (BCAAs) should prevent the exercise-induced increase in the plasma concentration ratio of free tryptophan to other large neutral amino acids (including BCAAs) and thereby prevent an elevation in the level of 5-HT in the brain. In this study, subjects were given either a mixture of BCAAs in a carbohydrate solution or a placebo drink that contained only carbohydrates during a 30-km cross-country race. Several tasks to measure cognitive performance were performed before and after the race. When subjects were supplied with BCAAs, their performance in the different parts of the color-word test (words, colors and color words) was improved by an average of 3-7% (p < 0.05) after exercise, whereas there was no difference in performance before and after exercise in the subjects who were given the placebo. Furthermore, the experimental group, supplied with BCAAs, maintained their performance in the shape-rotation and figure-identification tasks, whereas an impairment in performance in these tests by 25% (p < 0.05) and 15% (p < 0.05), respectively, was found in the subjects who received the placebo. Thus, BCAA supplementation seemed to have an effect on the more complex tasks, whereas no effect could be detected on the less demanding tasks. However, an intake of BCAAs during exercise modified only slightly the exercise-induced changes in mood.

Adult↗