L-Arginine Research

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L-Arginine Research - Study 1

J Cardiovasc Pharmacol Ther. 2010 Oct 11. [Epub ahead of print]Protective Effect of L-Arginine in Experimentally Induced Myocardial Ischemia: Comparison With Aspirin.

Saleh AI, Abdel Maksoud SM, El-Maraghy SA, Gad MZ.

Biochemistry Department, Faculty of Pharmacy, German University in Cairo, New Cairo, Egypt.Abstract

OBJECTIVE: Coronary artery diseases including myocardial ischemia (MI) remain one of the leading causes of death worldwide. This study was designed to compare the protective effect of l-arginine versus aspirin from the biochemical changes associated with MI injury. Experimental design: Four groups of male New Zealand white rabbits were investigated. Normal group (n = 8) rabbits were fed standard chow pellets, untreated MI group (n = 16), where hypercholesterolemia was induced by feeding the animals with a diet containing 2% cholesterol for 28 days, l-arginine group (n = 12) rabbits were fed a 2% cholesterol-enriched diet in conjunction with l-arginine (2.25 g %) in drinking water for 28 days, and aspirin group (n = 12) rabbits were fed 2% cholesterol-enriched diet in conjunction with aspirin administered orally (0.7 mg/kg per d) for 28 days. After 28 days, MI was induced in all groups, except the normal group, by a single subcutaneous (sc) injection of isoproterenol hydrochloride (0.2 mg/kg body weight [bw]). Animals were sacrificed 6 hours later.

RESULTS: Our results showed that l-arginine was more effective than aspirin in reducing platelet aggregation, reducing low-density lipoprotein (LDL) oxidizability, preventing aortic intimal thickening, and maintaining histological architecture of the myocardium. Both drugs, however, had similar positive effects on plasma fibrinogen levels and on the prevention of myocardial release of cardiac troponin I and creatine kinase-MB. The effect on hypercholesterolemia was insignificant for both drugs. Aspirin was more effective than l-arginine in prolonging prothrombin time.

CONCLUSION: l-arginine supplementation represents a potentially novel nutritional strategy for preventing and treating coronary artery diseases especially in cases of aspirin resistance and/or hypersensitivity.

PMID: 20938038 [PubMed - as supplied by publisher]

L-Arginine Research - Study 2

Am J Clin Nutr. 2010 Sep 29. [Epub ahead of print]Perioperative arginine-supplemented nutrition in malnourished patients with head and neck cancer improves long-term survival.

Buijs N, van Bokhorst-de van der Schueren MA, Langius JA, Leemans CR, Kuik DJ, Vermeulen MA, van Leeuwen PA.

Departments of Surgery, VU University Medical Center, MB Amsterdam, Netherlands.Abstract

BACKGROUND: Plasma arginine concentrations are lower in patients with cancer, which indicates that arginine metabolism may be disturbed in these patients. Arginine supplementation has been associated with positive effects on antitumor mechanisms and has been shown to reduce tumor growth and to prolong survival. Furthermore, the prognosis of patients with head and neck cancer remains disappointing. Insufficient intake frequently leads to malnutrition, which contributes to high morbidity and mortality rates.

OBJECTIVE: The aim of this study was to assess the long-term effects of perioperative arginine supplementation in severely malnourished patients with head and neck cancer.

DESIGN: In this double-blind, randomized, controlled trial, we randomly assigned 32 severely malnourished patients with head and neck cancer to receive 1) standard perioperative enteral nutrition (n = 15) or 2) arginine-supplemented perioperative enteral nutrition (n = 17). The primary outcome was long-term (≥10 y) survival. Secondary outcomes included the long-term appearance of locoregional recurrence, distant metastases, and second primary tumors.

RESULTS: No significant differences in baseline characteristics were observed between groups. The group receiving arginine-enriched nutrition had a significantly better overall survival (P = 0.019) and better disease-specific survival (P = 0.022). Furthermore, the arginine-supplemented group had a significantly better locoregional recurrence-free survival (P = 0.027). No significant difference in the occurrence of distant metastases or occurrence of a second primary tumor was observed between the groups.

CONCLUSION: Perioperative arginine-enriched enteral nutrition significantly improved the long-term overall survival and long-term disease-specific survival in malnourished patients with head and neck cancer.

PMID: 20881073 [PubMed - as supplied by publisher]

L-Arginine Research - Study 3

J Pediatr Hematol Oncol. 2010 Oct;32(7):e249-58.

Sullivan KJ, Kissoon N, Sandler E, Gauger C, Froyen M, Duckworth L, Brown M, Murphy S.

Department of Anesthesia and Critical Care Medicine, Nemours Children's Clinic, Jacksonville, Florida 32207, USA. ksulliva@nemours.org

Comment in:

* J Pediatr Hematol Oncol. 2010 Oct;32(7):e247-8.

Abstract

INTRODUCTION: Decreased exhaled nitric oxide levels (FE(NO)) have been described in patients with sickle cell disease (SCD) and a history of acute chest syndrome (ACS) when compared with non-ACS controls. Oral arginine supplementation has been shown to increase FE(NO) in healthy participants, but its effect in SCD patients is not known.

OBJECTIVE: To determine the effect of oral arginine intake on FENO in sickle cell patients with and without history of ACS, and in healthy controls.

HYPOTHESIS: No differences in the FE(NO) increase were seen in SCD patients with a history of ACS (ACS+) compared with healthy controls (HC) and SCD patients without history of ACS (ACS-).

MATERIALS AND METHODS: ACS+ (n=6), ACS- (n=9), and HC (n=7) patients were studied. At baseline, and after the administration of escalating doses of oral L-arginine (0.1, 0.2, and 0.4 g/kg), serial measurements were made of the following: FE(NO), plasma concentrations of arginine, ornithine, citrulline, aspartate, glutamate, arginine/ornithine ratio, nitrite, nitrate, heart rate (HR), respiratory rate (RR), blood pressure (BP), oxygen saturation (SpO2), forced expiratory volume in 1 second (FEV1), and forced vital capacity (FVC).

MAIN RESULTS: At baseline, FE(NO) did not differ among the groups. ACS- and ACS+ groups were deficient in arginine, and had decreased FEV1, FVC, and SaO2 when compared with HC patients. After arginine supplementation, FE(NO), arginine, ornithine, citrulline, nitrite, and the arginine/ornithine ratio increased similarly in all groups. Changes from baseline for HR, BP, SpO2, RR, FEV1, and FVC were minimal and similar in all groups.

CONCLUSIONS: In contrast to our earlier study, ACS+ patients had similar FE(NO) values when compared with ACS- and HC patients. All SCD patients were arginine deficient at baseline and showed impairment in respiratory physiology when compared with HC patients. After arginine supplementation, FE(NO) concentration increased in all groups to a similar degree, and lung function and physiologic parameters were minimally affected. The physiologic significance of alterations in FE(NO) in SCD patients and its relationship to ACS predilection requires further delineation.

PMID: 20724949 [PubMed - in process]

L-Arginine Research - Study 4

J Appl Physiol. 2010 Aug 19. [Epub ahead of print]Acute L-arginine supplementation reduces the O2 cost of moderate-intensity exercise and enhances high-intensity exercise tolerance.

Bailey SJ, Winyard PG, Vanhatalo A, Blackwell JR, Dimenna FJ, Wilkerson DP, Jones AM.

1Exeter University.Abstract

It has recently been reported that dietary nitrate supplementation which increases plasma nitrite concentration, a biomarker of nitric oxide (NO) availability, improves exercise efficiency and exercise tolerance in healthy humans. We hypothesised that dietary supplementation with L-arginine, the substrate for nitric oxide synthase (NOS), would elicit similar responses. In a double-blind, crossover study, nine healthy males (aged 19-38 years) consumed a 500 mL beverage containing 6 g of L-arginine (ARG) or a placebo beverage (PLA), and completed a series of 'step' moderate-intensity and severe-intensity exercise bouts 1 h post-ingestion. Plasma [nitrite] was significantly greater following L-arginine consumption compared to placebo (ARG: 331 +/- 198 vs. PLA: 159 +/- 102 nM; P<0.05) and systolic blood pressure was significantly reduced (ARG: 123 +/- 3 vs. PLA: 131 +/- 5 mmHg; P<0.01). The steady-state VO(2) during moderate-intensity exercise was reduced by 7% in the ARG condition (ARG: 1.48 +/- 0.12 vs. PLA: 1.59 +/- 0.14 L*min(-1); P<0.05). During severe-intensity exercise, the VO(2) slow component amplitude was reduced (ARG: 0.58 +/- 0.23 vs. PLA: 0.76 +/- 0.29 L*min(-1); P<0.05) and the time-to-exhaustion was extended (ARG: 707 +/- 232 s vs. PLA: 562 +/- 145 s; P<0.05) following ARG. In conclusion, similar to the effects of increased dietary nitrate intake, elevating NO bioavailability through dietary L-arginine supplementation reduced the O(2) cost of moderate-intensity exercise and blunted the VO(2) slow component and extended the time-to-exhaustion during severe-intensity exercise.

PMID: 20724562 [PubMed - as supplied by publisher]

L-Arginine Research - Study 5

Oxid Med Cell Longev. 2009 Sep-Oct;2(4):231-7.Oral administration of L-arginine in patients with angina or following myocardial infarction may be protective by increasing plasma superoxide dismutase and total thiols with reduction in serum cholesterol and xanthine oxidase.

Tripathi P, Chandra M, Misra MK.

Department of Biochemistry, Lucknow University, Lucknow, India.Abstract

Administration of L-arginine has been shown to control ischemic injury by producing nitric oxide which dilates the vessels and thus maintains proper blood flow to the myocardium. In the present study attempt has been made to determine whether oral administration of L-arginine has any effect on oxidant/ antioxidant homeostasis in ischemic myocardial patients [represented by the patients of acute angina (AA) and acute myocardial infarction (MI)]. L-arginine has antioxidant and antiapoptotic properties, decreases endothelin-1 expression and improves endothelial function, thereby controlling oxidative injury caused during myocardial ischemic syndrome. Effect of L-arginine administration on the status of free radical scavenging enzymes, pro-oxidant enzyme and antioxidants viz. total thiols, carbonyl content and plasma ascorbic acid levels in the patients has been evaluated. We have observed that L-arginine administration (three grams per day for 15 days) resulted in increased activity of free radical scavenging enzyme superoxide dismutase (SOD) and increase in the levels of total thiols (T-SH) and ascorbic acid with concomitant decrease in lipid per-oxidation, carbonyl content, serum cholesterol and the activity of proxidant enzyme, xanthine oxidase (XO). These findings suggest that the supplementation of L-arginine along with regular therapy may be beneficial to the patients of ischemic myocardial syndromes.

PMID: 20716909 [PubMed - in process]PMCID: PMC2763261

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