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Old 04-08-2006, 07:35 AM
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Arginine / Nitric Oxide and Recovery / Growth:

Quote:
"Nitric oxide generation from L-arginine is required for optimal human peripheral blood lymphocyte DNA synthesis."- Efron DT, Kirk SJ, Regan MC, Wasserkrug HL, Barbul A. Department of Surgery, Sinai Hospital of Baltimore, MD 21215.

"These data suggest that nitric oxide synthesis is critical to wound collagen accumulation and acquisition of mechanical strength".

Nitric oxide regulates wound healing - J Surg Res. 1996 Jun;63(1):237-40. Schaffer MR, Tantry U, Gross SS, Wasserburg HL, Barbul A.

"NO has been shown to be cytostatic to multiple cell types including endothelial cells, smooth muscle cells, hepatocytes, and fibroblasts [37, 38 and 39]. Depending on the cell type this effect can be cGMP dependent [40] or independent [41]. Target enzymes include complexes I and II of the respiratory chain [42] and ribonucleotide reductase [43], a rate-limiting enzyme in the DNA synthetic pathway. NO is cytostatic in large doses. However, several studies have shown that NO can stimulate cell proliferation when added in low concentrations [44 and 45]. Recent evidence suggests that NO can also reduce cell proliferation by inhibiting ornithine-decarboxylase activity, the rate limiting enzyme for polyamine formation [46].

NO also regulates gene expression [47 and 48] and cellular differentiation [49 and 50]. Regulation of gene expression by NO probably occurs indirectly, through amplification of other regulatory mechanisms [51]. For example, although NO is critical for wound collagen deposition, clear-cut enhancement of collagen synthesis or gene expression has not been found (see the following). Collagen metabolism and accumulation are tightly regulated through the activity of collagenases and their inhibitors, tissue inhibitors of metalloproteinases (TIMP). Inhibiting the collagenolytic pathway can enhance collagen accumulation. Addition of the NO donor SNAP to rat mesangial cells increases gelatinase A activity [52] whereas rat fibroblasts collagenase activity is unaffected by SNAP [41]. Another potential mechanism of posttranslational collagen regulation by NO is regulation of protein kinase C (PKC) activity [53 and 54]. By inhibiting PKC activity, NO could down-regulate PKC-related collagen synthesis in fibroblasts.

when humans and animals are fed an arginine-enriched diet there is improved healing as measured by collagen deposition and breaking strength"



"We also review the evidence that in certain nutritional or disease states or in certain stages of development otherwise dispensable amino acids may become indispensable. Arginine, citrulline, ornithine, cysteine, and tyrosine thus may be considered as acquired indispensable amino acids. Evidence for the indispensability of taurine is also considered. We propose a classification of the indispensability of amino acids based on clinical and therapeutic considerations."

- Newer concepts of the indispensable amino acids. Laidlaw SA, Kopple JD. Am J Clin Nutr. 1987 Oct;46(4):593-605.

"Some stress conditions that put an increased demand on the body for the synthesis of L-arginine include trauma (including surgical trauma), sepsis and burns. Under these conditions, L-arginine becomes essential, and it is then very important to ensure adequate dietary intake of the amino acid to meet the increased physiological demands created by these situations.

L-arginine, even when it is not an essential amino acid as defined above, is a vital one. In addition to participating in protein synthesis, it plays a number of other roles in the body. These include the detoxification of ammonia formed during the nitrogen catabolism of amino acids via the formation of urea. In addition, L-arginine is a precursor in the formation of nitric oxide, creatine, polyamines, L-glutamate, L-proline, agmatin (a possible neurotransmitter in the brain) and the arginine-containing tetrapeptide tuftsin, believed to be an immunomodulator. L-arginine is a glycogenic amino acid; it can be converted to D-glucose and glycogen if needed by the body or it can be catabolized to produce biological energy.

L-arginine, when administered in high doses, stimulates pituitary release of growth hormone and prolactin and pancreatic release of glucagon and insulin. Intravenous L-arginine may be used as an aid in the evaluation of problems with growth and stature that may be due to growth hormone deficiency. Intravenous arginine hydrochloride may be used as a fourth-line agent in the treatment of severe metabolic alkalosis. L-arginine is also used as an immunonutrient in enteral and parenteral nutrition to help improve the immune status in those suffering from sepsis, burns and trauma."

"L-arginine supplements theoretically may potentiate the effects of organic nitrates if taken concomitantly."
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