Category: amino acids


This investigation was designed to evaluate changes in plasma and muscle levels of free amino acids during an ultra-endurance exercise and following recovery. Nine male ultra-endurance trained athletes participated in a 24-h standardized endurance trial with controlled energy intake. The participants performed 12 sessions of running, kayaking and cycling (4 × each discipline). Blood samples were collected before, during and after exercise, as well as after 28 h of recovery. Muscle biopsies were taken before the test and after exercise, as well as after 28 h of recovery. During the 24-h exercise, plasma levels of branched-chain (BCAA), essential amino acids (EAA) and glutamine fell 13, 14 and 19% (P < 0.05), respectively, whereas their concentrations in muscle were unaltered. Simultaneously, tyrosine and phenylalanine levels rose 38 and 50% (P < 0.05) in the plasma and 66 and 46% (P < 0.05) in muscle, respectively. After the 24-h exercise, plasma levels of BCAA were positively correlated with muscle levels of glycogen (r (2) = 0.73, P < 0.05), as was the combined concentrations of muscle tyrosine and phenylalanine with plasma creatine kinase (R (2) = 0.55, P < 0.05). Following 28-h of recovery, plasma and muscle levels of amino acids had either returned to their initial levels or were elevated. In conclusion, ultra-endurance exercise caused significant changes elevations in plasma and muscle levels of tyrosine and phenylalanine, which suggest an increase in net muscle protein breakdown during exercise. There was a reduction in plasma concentrations of EAA and glutamine during exercise, whereas no changes were detected in their muscle concentration after exercise.

[PubMed – as supplied by publisher]

Low protein diet and ketosteril in predialysis patients with renal failure


Clinic of Nephrology, Higher Medical Institute, 15A Vassil Aprilov St., 4000 Plovdiv, Bulgaria.


After a short review of the contemporary understanding of amino acid supplementation to low protein diets in patients with uremia we present the results of administration of ketosteril in 20 low-protein-diet patients on such a diet.


Twenty patients (10 men and 10 women) with stable II and III stage chronic renal failure were assigned to a low protein diet (protein up to 40 g/day). Ketosteril (6 tablets a day) were added to the diet. Some of the basic markers of protein metabolism and nitrogen balance were followed.


No evidence of deteriorated protein synthesis was found in the therapy thus administered. Serum urea and creatinine values did not change and even tended to decrease. Glomerular filtration was found to increase insignificantly more markedly in the patients with renal failure in the early stages.


A low protein diet with increased content of essential amino acids and their keto-analogues does not deteriorate the nitrogen balance of patients with chronic renal failure. By adding essential amino acids and keto-analogues a normal protein metabolism is maintained in spite of the reduce intake of protein substances with the diet. Supplementation of the diet of chronic renal failure patients with essential amino acids and keto-analogues allows a considerable reduction of the protein intake to be achieved which brings about reduction of glomerular hyperfiltration which actually retards the progression of renal failure and improves its short-term prognosis.

[PubMed – indexed for MEDLINE]

Effect of a keto acid-amino acid supplement on the metabolism and renal elimination of branched-chain amino acids in patients with chronic renal insufficiency on a low protein diet


Department of Nephrology, Transplant Center, Institute of Clinical and Experimental Medicine, Postgraduate Medical School, Prague, Czech Republic.


The aim of our study was to evaluate the effect of a low-protein diet supplemented with keto acids-amino acids on renal function and urinary excretion of branched-chain amino acids (BCAA) in patients with chronic renal insufficiency (CRI). In a prospective investigation 28 patients with CRI (16 male, 12 female, aged 28-66 yrs, CCr 18.6 +/- 10.2 ml/min) on a low-protein diet (0.6 g of protein /kg BW/day and energy intake 140 kJ/kg BW/day) for a period of one month were included. Subsequently, this low protein diet was supplemented with keto acids-amino acids at a dose of 0.1 g/kg BW/day orally for a period of 3 months. Examinations performed at baseline and at the end of the follow-up period revealed significant increase in the serum levels of BCAA leucine (p < 0.02), isoleucine (p < 0.03), and valine (p < 0.02) while their renal fractional excretion declined (p < 0.02, p < 0.01 resp.). Keto acid-amino acid administration had no effect on renal function and on the clearance of inulin, para-aminohippuric acid. Endogenous creatinine and urea clearance remained unaltered. A significant correlation between fractional excretion of sodium and leucine (p < 0.05) and a hyperbolic relationship between inulin clearance and fractional excretion of BCAA (p < 0.01) were seen. Moreover, a significant decrease in proteinuria (p < 0.02), plasma urea concentration and renal urea excretion and a rise in albumin level (p < 0.03) were noted. We conclude that in patients with CRI on a low protein diet the supplementation of keto acids-amino acids does not affect renal hemodynamics, but is associated–despite increases in plasma concentrations–with a reduction of renal amino acid and protein excretion suggesting induction of alterations in the tubular transport mechanisms.

[PubMed – indexed for MEDLINE]

The effect of L-ornithine hydrochloride ingestion on performance during incremental exhaustive ergometer bicycle exercise and ammonia metabolism during and after exercise.


Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, Japan.



L-Ornithine has an important role in ammonia metabolism via the urea cycle. This study aimed to examine the effect of L-ornithine hydrochloride ingestion on performance during incremental exhaustive ergometer bicycle exercise and ammonia metabolism during and after exercise.


In all, 14 healthy young adults (age: 22.2±1.0 years, height: 173.5±4.6 cm, body mass: 72.5±12.5 kg) who trained regularly conducted incremental exhaustive ergometer bicycle exercises after -ornithine hydrochloride supplementation (0.1 g/kg, body mass) and placebo conditions with a cross-over design. The exercise time (sec) of the incremental ergometer exercise, exercise intensity at exhaustion (watt), maximal oxygen uptake (ml per kg per min), maximal heart rate (beats per min) and the following serum parameters were measured before ingestion, 1 h after ingestion, just after exhaustion and 15 min after exhaustion: ornithine, ammonia, urea, lactic acid and glutamate. All indices on maximal aerobic capacity showed insignificant differences between both the conditions.


Plasma ammonia concentrations just after exhaustion and at 15 min after exhaustion were significantly more with ornithine ingestion than with placebo. Plasma glutamate concentrations were significantly higher after exhaustion with ornithine ingestion than with placebo.


It was suggested that, although the ingestion of L-ornithine hydrochloride before the exercise cannot be expected to improve performance, it does increase the ability to buffer ammonia, both during and after exercise.

[PubMed – indexed for MEDLINE]
In the present study, oral supplementation of l-arginine in rats was evaluated for its anti-stress and adaptogenic activity using the cold (5°C)–hypoxia (428 mmHg)–restraint (C-H-R) animal model. A dose-dependent study of l-arginine was carried out at doses of 12.5, 25.0, 50.0, 100.0, 200.0 and 500.0 mg/kg body weight, administered orally 30 min prior to C-H-R exposure. The time taken by the rat to attain a rectal temperature of 23°C (Trec 23°C) during C-H-R exposure and its recovery to Trec 37°C at normal atmospheric pressure and 32 ± 1°C were used as biomarkers of anti-stress and adaptogenic activity. Biochemical parameters related to lipid peroxidation, anti-oxidants, cell membrane permeability, nitric oxide and stress, with and without administration of the least effective l-arginine dose, were measured in rats on attaining Trec 23°C and Trec 37°C. The least effective adaptogenic dose of l-arginine was 100.0 mg/kg body weight. The C-H-R exposure of control rats, on attaining Trec 23°C, resulted in a significant increase in plasma malondialdehyde (MDA), blood lactate dehydrogenase (LDH) and a decrease in blood catalase (CAT) and plasma testosterone levels. On recovery (Trec 37°C) of control rats, there was a further decrease in CAT and plasma testosterone, and an increase in LDH. l-Arginine supplementation resulted in a significant decrease in plasma MDA, an increase in blood superoxide dismutase (SOD), CAT levels maintained at control values and a lower increase in LDH compared with controls (45.3 versus 58.5% and 21.5 versus 105.2%) on attaining Trec 23°C during C-H-R exposure and on recovery to Trec 37°C. The results suggested that l-arginine possesses potent anti-stress activity during C-H-R exposure and recovery from C-H-R-induced hypothermia.
Keywords: hypoxia, cold, rectal temperature, oxidative stress
Biological stress is a response to physical, chemical, biological and emotional changes, consisting of a pattern of metabolic and behavioral reactions that helps to strengthen the organism (1). During stressful situations, the energy requirement of the organism is increased, resulting in enhanced generation of free radicals (24). Free radicals cause oxidation of nucleic acids and proteins. Free radicals also damage biomembranes, reflected by increased lipid peroxidation, thereby compromising cell integrity and function. During this process, the ability of the body’s defense system to combat the oxidative stress may diminish due to reduced anti-oxidants. If the stress level increases beyond the threshold limit of an individual, it results in decreased performance and stress-induced disorders. The management of unusual stress therefore has acquired enormous significance in day-to-day life. Such a management does not endeavor to eliminate stress but rather to raise the threshold level of the organism beyond which stress would start injuring and disturbing life processes. It is possible to support the body’s adaptation by using food supplements, dietary elements, herbs and minerals for increasing physical and mental performance, described in various oriental systems of medicine including the ancient Indian medical system Ayurveda. Such substances have been described as ‘adaptogens’ (5). In strenuous conditions, the physical performance of the organism is dependent on the availability of appropriate macro- and micronutrients required in excess on account of their increased utilization during stressful situations (6). Supplementation with various macro- and micronutrient and herbal preparations has been evaluated for their adaptogenic activity during exposure to a stressful environment (710).
It has been suggested that amino acid supplementation might be able to increase human performance to a limited extent (11). An amino acid mixture supplementation was observed to enhance adrenocortical hormone, luteinizing hormone and follicle-stimulating hormone response to corticotropin-releasing hormone in athletes (12). Under certain metabolic, developmental or pathophysiological conditions, some of the non-essential amino acids become essential and are designated as ‘conditionally essential’. Arginine and glutamine are known to be conditionally essential amino acids (13). l-Arginine plays important roles in the urea cycle, protein synthesis, as a precursor of polyamines and creatine, and as a substrate for synthesis of nitric oxide (NO). NO was shown to be an endothelial-derived relaxation factor, a vasodilator, which acted as a modulator of vascular tone to regulate blood flow and blood pressure (14). NO is also involved in enhancement of the thermogenic function of brown adipose tissue in rats (15). It is interesting that herbs with adaptogenic activity, e.g. Panax ginseng, have been shown to contain large amounts of arginine (16).
It was shown that endogenous plasma arginine levels decreased significantly after 30 min immobilization stress and remain suppressed during a 3.5 h post-stress period (17). In burn patients, there was a higher rate of arginine loss from the body and supplementation of arginine was required to maintain homeostasis and promote recovery (18). In the present study, the anti-stress and adaptogenic effect, if any, of l-arginine supplementation was studied in rats subjected to a comprehensive and generalized stress of cold (5°C)–hypoxia (428 mmHg)– restraint (C-H-R) (19).


Arginine alpha ketoglutarate or AAKG is a chemical compound made from combining the salt of arginine and alpha ketoglutaric acid, two important chemical compounds necessary to produce the compound nitric oxide. It is a well known compound because it is widely sold in the market as a dietary supplement that builds muscle mass.

Arginine alpha ketoglutarate supplement is sold in the market for body building purposes. It is administered to patients who have just undergone surgery to promote hormone production and release of insulin for the purpose of healing wounds in a speedy manner. AAKG has the ability to speed up recovery after a serious injury and is also used to treat severe burns and other traumatic damage to the body.

Previous laboratory experiments show that AAKG supplementation dramatically increased collagen production deposited in a wound as evidenced by the presence of the substance hydroxyproline in the wound.

Wound healing is greatly enhanced by the arginine content in AAKG and increases the producttion of hydroxyproline levels in the wound area when tested among the diabetic laboratory animals. AAKG supplementation also significantly increased the amount of fluid nitrate and nitrite levels in the site of the injury.

It is also believed that this substance can reduce blood pressure. Nitric oxide, which is produced from arginine has the ability to dilate blood vessels resulting to the relaxation of muscles in the arteries, arterioles and veins. It is believed that the nitric oxide content in AAKG is responsible for the production of muscle proteins in the body and further enhances muscular strength and endurance, however further research is needed to confirm this claim. It ensures a regular supply of healthy blood to the muscles and other parts of the body.

During great stress and traumatic injury, the glutamine and arginine content found in our skeletal muscles are significantly increased with arginine alpha ketoglutarate supplementation.

It is also believed to increase the amount of growth hormones especially in children where a study showed that the AAKG supplementation indeed increased the levels of growth hormones and amino acids in the body.

The benefits from arginine alpha ketoglutarate are almost the same as those derived from arginine. It is used to speed up the healing of wounds especially after surgery and repair of cells and tissues of the body after severe wounds and body injury. It also treats headaches caused by severe migraine and treats impotence among the male population.

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L-Arginine as a Potential Ergogenic Aid in Healthy Subjects

Authors: Álvares, Thiago S.; Meirelles, Cláudia M.; Bhambhani, Yaagesh N.; Paschoalin, Vânia M.F.; Gomes, Paulo S.C.


Dietary supplements containing L-arginine, a semi-essential amino acid, are one of the latest ergogenic aids intended to enhance strength, power and muscle recovery associated with both aerobic and resistance exercise. L-arginine is claimed to promote vasodilation by increasing nitric oxide (NO) production in the active muscle during exercise, improving strength, power and muscular recovery through increased substrate utilization and metabolite removal, such as lactate and ammonia. Research on L-arginine has recently tested this hypothesis, under the assumption that it may be the active compound associated with the vasodilator effects of NO. There were only five acute studies retrieved from the literature that evaluated exercise performance after L-arginine supplementation, three of which reported significant improvements. Regarding studies on chronic effects, eight studies were encountered: four reported enhancements in exercise performance, whilst four reports showed no changes. Whether these improvements in exercise performance – regardless of the aerobic or anaerobic nature of the exercise – can be associated with increases in NO production, has yet to be demonstrated in future studies. Low oral doses (≤20 g) are well tolerated and clinical side effects are rare in healthy subjects. In summary, it is still premature to recommend dietary supplements containing L-arginine as an ergogenic aid for healthy physically active subjects.


20 ml 0,2g/ml L-arginine HCL infusion by Fresenius-Kabi $15

Investigation of the effects of oral supplementation of arginine in the increase of muscular strength and mass

Gerseli Angeli
1, Turibio Leite de Barros1, Daniel Furquim Leite de Barros2 and Marcelo Lima3


Introduction: Oral administration of arginine has been associated with physical performance improvement due to probable decrease of muscular fatigue derived from the vasodilatation factor of the nitric oxide over the skeletal muscles.
Objective: to evaluate the effects of oral administration of L-Arginine during an exercise program with weights. Methods: 20 male individuals, randomly divided in two groups: A and B, were submitted to eight weeks of training with weights (three times per week). Group A used 3 grams of L-Arginine + vitamin C during the eight weeks and group B used only vitamin C (control group).
Results: After eight weeks of training, group A presented body weight values and lean mass significantly higher (p < 0.05), body fat percentage significantly lower (p< 0.05), and strength of lower limbs significantly higher (p < 0.05), while group B did not present significant differences for the same period.
Conclusion: Oral administration of arginine associated with a training program with weights increased the stimuli of the exercise to the skeletal muscles level, enabling hence, increase of
muscular strength and mass.