Administration Of L-arginine Research Articles

Antiatherogenic Effect of L-Arginine in Streptozotocin-Induced Diabetic Rats

L-Arginine is one of the essential amino acids elaborated in numerous areas of human physiology which produce nitric oxide (NO). Current study was designed to examine the antiatherogenic and anti-diabetic activities of L-arginine in experimental diabetic rats’ model. Fifty rats were divided into; Control group, L-Arginine group, Diabetic group, Treated group and Prophylactic group. Fasting blood samples were collected from all groups for determination of fasting blood glucose, insulin, insulin resistance, atherogenic index (AI), cardiac risk ratio (CRR), atherogenic coefficient(AC), intercellular adhesion molecule-1 (I-CAM-1), tumor necrosis factor alpha (TNF-α), and nitric oxide (NO). The result showed that oral administration of L-arginine induced significant decrease in the plasma level of I-CAM-1, TNF-α, AC, AI,CRR, glucose, and insulin resistance while induced significant increase in NO, and insulin levels in the treated group . In conclusion, L-arginine may be a novel nutrient, which improves the endothelial function and protects against the development of atherosclerosis in diabetic rats.

Arginine therapy in mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes.

Purpose of reviewWe would like to inform clinicians that the systematic administration of oral and intravenous l-arginine is therapeutically beneficial and clinically useful for patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS), when they maintain plasma arginine concentration at least 168 μmol/l.Recent findingsMELAS is associated with endothelial dysfunction by decreased plasma l-arginine, nitric oxide (NO), and cyclic guanosine monophosphate. Endothelial dysfunction is also evident using flow-mediated vasodilation measurement by high-resolution Doppler echocardiography in the forearm artery in patients with MELAS. l-arginine is known to be an important precursor of NO to normalize the endothelial function in MELAS. In our clinical trial followed by 7 years follow-up study, the systematic administration of l-arginine to patients with MELAS significantly improved the survival curve of patients compared with natural history. Maintaining plasma arginine concentration at least 168 μmol/l may prevent the ictuses through the putative pathophysiologic mechanism and optimal normalization of endothelial dysfunction.SummaryNeither death nor bedriddenness occurred during the 2-year clinical trials, and the latter did not develop during the 7-year follow-up despite the progressively neurodegenerative and eventually life-threatening nature of MELAS. Therapeutic regimen of l-arginine on MELAS may be beneficial and clinically useful for patient care with MELAS.

Evaluation of the role of L-arginine on spermatological parameters, seminal plasma nitric oxide levels and arginase enzyme activities in rams.

The purpose of this study is to investigate the effects of L-arginine on spermatological parameters, seminal plasma nitric oxide levels and arginase enzyme activities. Fertile rams that are 2-3years old and weighing 50-60kg were used as material. The semen was collected by artificial vagina at 1st, 4th, 24th, 48th, 72nd, 96th and 120th hours for the control group before L-arginine administration. For treatment groups, L-arginine was administered intraperitoneally at a dose of 5mgkg-1 bw-1 and semen was collected at the time point described for the control group. Spermatological characteristics of semen samples (semen volume, pH, sperm motility, concentration and abnormal sperm rate), seminal plasma nitric oxide levels and arginase enzyme activities were determined. Increased seminal plasma nitric oxide level (p<.01), seminal plasma arginase activity (p<.01), semen volume (p<.05), semen mass activity (p<.05), sperm motility (p<.05) and concentration (p<.01) and decreased abnormal sperm rate (p<.05 and p<.01) were observed by L-arginine administration. In conclusion, it may be concluded that L-arginine application in rams during the breeding season may have positive effects on rams' reproductive performance.

Oral L-Arginine lower neovascularization and the number of fibroblasts but failed to increase nitric oxide and epithelialization in the healing process of male white diabetic wistar rats (Rattus norvegicus)

Introduction: Oral L-Arginine is a conditional essential amino acid that plays a role in wound healing in DM. The role of arginine in diabetic wounds is by enhancing blood circulation in the injured area and increasing oxygen supply to the wound tissue. The purpose of this study to prove the administration of oral L-Arginine toward vascularization status in wound healing of male white rats wistar diabetes mellitus.&#x0D; Methods: A randomized posttest only control group study using with 36 diabetic induced wistar rats (Rattus Norvegicus) aged 2-3 months and weighing 180-200gram which then divided randomly into two groups. Nitric oxide level was measured on the third day and each group was then further divided into two groups for examination of neovascularization, fibroblasts and epithelialization on the seventh day and on the tenth day.&#x0D; Results: Administration oral L-Arginine failed to induce any significant change in Nitric Oxide level and wound gap closure. On the other hand, the results showed that the mean neovascularization was significantly different between the two groups on the 10th day (Control group vs intervention group: 4.22±1922 vs1.89±1364; p=0.009). In addition, the mean number of fibroblast at the 10th day was also significantly different (Control group vs intervention group: 74.11±28.57 vs 38.11±20.90; p=0.008).&#x0D; Conclusion: In conclusion, oral L-Arginine did not significantly affect nitric oxide and epithelialization while decreased neovascularization and the number of fibroblasts on day tenth in the healing process of male white rats diabetes mellitus

Effect of the Hemoxygenase-Carbon Monoxide (HO-CO) System on the Reactivity of Uterine Artery Branches in Rats.

First to fourth-order branches of the uterine artery in sexually mature female Wistar rats were studied by biomicroscopy. After administration of a CO donor hemin (60 mM), the diameters of large uterine branches with a well-developed muscle layer markedly increased, while the increase in diameter of small vessels with one often interrupted layer of smooth muscle cells increased insignificantly. Zinc protoporphyrin IX (30 mM) in all cases blocked this effect. However, zinc protoporphyrin IX does not affect NO-mediated reaction of the branches of the uterine artery caused by administration of L-arginine (60 mM), and L-NAME did not significantly affect reactivity of uterine artery branches associated with the hemoxygenase-CO system. In contrast to NO, CO produced less potent and rapid, but more sustained effect. The target for the hemoxygenase-CO system is mainly arteries with developed muscular layer, while the target for the NO synthase-NO is small vessels where endothelium plays a Rdecisive role in the regulation of vasomotor reactions.

Effect of L-Arginine on Titin Expression in Rat Soleus Muscle After Hindlimb Unloading.

Nitric oxide (NO), produced by NO-synthases via L-arginine oxidation, is an essential trigger for signaling processes involved in structural and metabolic changes in muscle fibers. Recently, it was shown that L-arginine administration prevented the decrease in levels of the muscle cytoskeletal proteins, desmin and dystrophin, in rat soleus muscle after 14 days of hindlimb unloading. Therefore, in this study, we investigated the effect of L-arginine administration on the degree of atrophy changes in the rat soleus muscles under unloading conditions, and on the content, gene expression, and phosphorylation level of titin, the giant protein of striated muscles, able to form a third type of myofilaments—elastic filaments. A 7-day gravitational unloading [hindlimb suspension (HS) group] resulted in a decrease in the soleus weight:body weight ratio (by 31.8%, p < 0.05), indicating muscle atrophy development. The content of intact titin (T1) decreased (by 22.4%, p < 0.05) and the content of proteolytic fragments of titin (T2) increased (by 66.7%, p < 0.05) in the soleus muscle of HS rats, compared to control rats. The titin gene expression and phosphorylation level of titin between these two groups were not significantly different. L-Arginine administration under 7-day gravitational unloading decreased the degree of atrophy changes and also prevented the decrease in levels of T1 in the soleus muscle as compared to HS group. Furthermore, L-arginine administration under unloading resulted in increased titin mRNA level (by 76%, p < 0.05) and decreased phosphorylation level of T2 (by 28%, p < 0.05), compared to those in the HS group. These results suggest that administration of L-arginine, the NO precursor, under unloading decreased the degree of atrophy changes, increased gene expression of titin and prevented the decrease in levels of T1 in the rat soleus muscle. The results can be used to search for approaches to reduce the development of negative changes caused by gravitational unloading in the muscle.

NMDA receptors and L-arginine/nitric oxide/cyclic guanosine monophosphate pathway contribute to the antidepressant-like effect of Yueju pill in mice.

The present study aims to evaluate the involvement of N-methyl-d-aspartate receptor and nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) system in antidepressant-like effects of Yueju pill (YJ), a Chinese herbal medicine. The immobility time in tail suspension test (TST) and forced swim test (FST) was used to assess the antidepressant effects. Prior administration of L-arginine (750 mg/kg, intraperitoneal [i.p.]), a NO synthase substrate that enhances NO signaling or sildenafil (5 mg/kg, i.p.), a phosphodiesterase 5 inhibitor that enhances cGMP, blunted the antidepressant-like activity of YJ (2.7 g/kg, i.g.). Co-treatment of ineffective dose of YJ (1.35 g/kg, i.g.) with one of the reagents that suppress the NO/cGMP signaling, including methylene blue (10 mg/kg, i.p.), an inhibitor of NO synthase; 7-NI (7-nitroinidazole, 30 mg/kg, i.p.), an nNOS specific inhibitor; L-NAME (10 mg/kg, i.p.), a non-specific inhibitor of NO synthase; and MK-801 (0.05 mg/kg, i.p.), an NMDA receptor antagonist, reduced the immobility time in TST and FST, compared with those in vehicle or single drug treatment groups. Neither above drugs alone or co-administrated with YJ affected locomotor activity or anxiety behavior in open field test. Thus, our results suggest that the antidepressant-like action of YJ may depend on the inhibition of NMDA/NO/cGMP pathway.

Ca2+ Influx Channel Inhibitor SARAF Protects Mice From Acute Pancreatitis

Pancreatitis is characterized by increased influx of Ca2+ into acinar cells, by unknown mechanisms. Inhibitors of Ca2+ influx channels could be effective in treating acute pancreatitis, but these have deleterious side effects that can result in death. We investigated the expression patterns and functions of acinar cell Ca2+ channels and factors that regulate them during development of acute pancreatitis, along with changes in the channel inactivator store-operated calcium entry-associated regulatory factor (SARAF). We investigated whether SARAF is a target for treatment of acute pancreatitis and its status in human with pancreatitis. We generated mice that expressed SARAF tagged with hemagglutinin, using CRISPR/Cas9 gene editing, and isolated acinar cells. We also performed studies with Saraf-/- mice, Sarafzf/zf mice, mice without disruption of Saraf (control mice), and mice that overexpress fluorescently labeled SARAF in acinar cells. We analyzed interactions between stromal interaction molecule 1 (STIM1) and SARAF in HEK cells stimulated with carbachol using fluorescence resonance energy transfer microscopy and immunoprecipitation. Mice were given injections of caerulein or L-arginine to induce pancreatitis. Pancreatic tissues and blood samples were collected and levels of serum amylase, trypsin, tissue damage, inflammatory mediators, and inflammatory cells were measured. We performed quantitative polymerase chain reaction analyses of pancreatic tissues from 6 organ donors without pancreatic disease (controls) and 8 patients with alcohol-associated pancreatitis. Pancreatic levels of Ca2+ influx channels or STIM1 did not differ significantly between acinar cells from mice with vs. without pancreatitis. By contrast, pancreatic levels of Saraf messenger RNA and SARAF protein initially markedly increased but then decreased during cell stimulation or injection of mice with caerulein, resulting in excessive Ca2+ influx. STIM1 interacted stably with SARAF following stimulation of HEK or mouse acinar cells with physiologic levels of carbachol, but only transiently following stimulation with pathologic levels of carbachol, leading to excessive Ca2+ influx. We observed reduced levels of SARAF messenger RNA in pancreatic tissues from patients with pancreatitis, compared with controls. SARAF knockout mice developed more severe pancreatitis than control mice after administration of caerulein or L-arginine, and pancreatic acinar cells from these mice had significant increases in Ca2+ influx. Conversely, overexpression of SARAF in acini reduced Ca2+ influx, eliminated inflammation, and reduced severity of acute pancreatitis. In mice with pancreatitis, SARAF initially increases but is then degraded, resulting in excessive, pathological Ca2+ influx by acinar cells. SARAF knockout mice develop more severe pancreatitis than control mice, whereas mice that express SARAF from a transgene in acinar cells develop less-severe pancreatitis. SARAF therefore appears to prevent pancreatic damage during development of acute pancreatitis. Strategies to stabilize or restore SARAF to acinar cells might be developed for treatment of pancreatitis.

Therapy of the rat hemorrhagic cystitis induced by cyclophosphamide. Stable gastric pentadecapeptide BPC 157, L-arginine, L-NAME

We focused on the cyclophosphamide-induced hemorrhagic cystitis (100 mg/kg/day intraperitoneally throughout three days) as a particular NO-system disturbance, and therapy possibilities. We demonstrated that it may be attenuated by subsequent administration of the NOS substrate L-arginine (100 mg/kg/day intraperitoneally), aggravated by NOS-blocker L-NAME (5 mg/kg/day intraperitoneally), all influenced by the stable gastric pentadecapeptide BPC 157 (10 μg/kg/day, 10 ng/kg/day, intraperitoneally or perorally, in drinking water). Regularly, cyclophosphamide dose- and time-dependently induced severe hemorrhagic cystitis lesions, gross lesions, and corresponding urothelial necrosis, vesical edema, erosion, hemorrhage, inflammation, and ulceration, microscopically. The bladder wet weight dramatically increased. Functionally, already after first cyclophosphamide administration, there is an increased leak point pressure. Until the second cyclophosphamide administration, L-arginine consistently attenuated regular cyclophosphamide-induced severe hemorrhagic cystitis lesions, grossly and microscopically, but not functionally. L-NAME aggravated these lesions and eradicated beneficial effect of L-arginine when combined. BPC 157 administration after cyclophosphamide, given in either dose or in either regimen markedly attenuated all cyclophosphamide lesions, grossly, microscopically. The increase of the bladder wet weight was consistently attenuated. Functionally, increased leak point pressure was reversed to the values noted in normal rats. The similar findings were noted in rats that received BPC 157 together with L-NAME or L-arginine, given alone or combined. Thus, the lesions are NO-related based on the administration of L-NAME as well as administration of L-arginine, and their mutual interaction, and counteraction by BPC 157 application. Likewise, we reveal new therapeutic possibilities, emphasizing stable gastric pentadecapeptide BPC 157 and L-arginine, versus L-NAME in rats underwent cyclophosphamide-induced cystitis.

The Effects of Oral l-Arginine and l-Citrulline Supplementation on Blood Pressure.

Nitric oxide (NO) is a well-known vasodilator produced by the vascular endothelium via the enzyme endothelial nitric oxide synthase (eNOS). The inadequate production of NO has been linked to elevated blood pressure (BP) in both human and animal studies, and might be due to substrate inaccessibility. This review aimed to investigate whether oral administration of the amino acids l-arginine (Arg) and l-citrulline (Cit), which are potential substrates for eNOS, could effectively reduce BP by increasing NO production. Both Arg and Cit are effective at increasing plasma Arg. Cit is approximately twice as potent, which is most likely due to a lower first-pass metabolism. The current data suggest that oral Arg supplementation can lower BP by 5.39/2.66 mmHg, which is an effect that is comparable with diet changes and exercise implementation. The antihypertensive properties of Cit are more questionable, but are likely in the range of 4.1/2.08 to 7.54/3.77 mmHg. The exact mechanism by which Cit and Arg exert their effect is not fully understood, as normal plasma Arg concentration greatly exceeds the Michaelis constant (Km) of eNOS. Thus, elevated plasma Arg concentrations would not be expected to increase endogenous NO production significantly, but have nonetheless been observed in other studies. This phenomenon is known as the “l-arginine paradox”.

The administration of L-cysteine and L-arginine inhibits biofilm formation in wild-type biofilm-forming yeast by modulating FLO11 gene expression.

Microbial biofilms are undesired in food manufacturing, drinking water distribution systems, and clinical realms. Yeast biofilms are particularly problematic because of the strong capacity of yeast cells to adhere to abiotic surfaces, cells, and tissues. Novel approaches have been developed over recent years to prevent the establishment of microbial biofilms, such as through the use of small molecules with inhibiting and dispersing properties. Here, we studied the inhibitory activity of 11 different amino acids on the biofilm formation ability of three wild-type Saccharomyces cerevisiae strains and the reference strain ∑1278b. Subsequent evaluation of different concentrations of the two most effective amino acids, namely, arginine and cysteine, revealed that they acted in different ways. Arginine prevented biofilm formation by reducing FLO11 gene expression; its addition did not affect cell viability and was even found to enhance cell metabolism (vitality marker) as determined by phenotype microarray (PM) analysis. On the contrary, the addition of cysteine reduced both cell viability and vitality as well as FLO11 expression. Thus, the use of cysteine and arginine as agents against biofilm formation can be diversified depending on the most desired action towards yeast growth.

Involvement of the L-arginine/Nitric Oxide/Cyclic GMP/KATP Channel Pathway and PPARγ Receptors in the Peripheral Antinociceptive Effect of Carbamazepine

Carbamazepine has been shown to exert analgesic effects in clinical and experimental pain situation. This study was conducted to evaluate its potential peripheral antinociceptive effects and the possible involvement of L-arginine/NO/cGMP/KATP channel pathway and PPARγ receptors in an animal model of pain. The antinociceptive effect induced by intraplantar administration of carbamazepine (100-1 000 μg/paw) was assessed using the formalin test in rats. To evaluate the involvement of L-arginine/NO/cGMP/KATP channel pathway in the antinociceptive action of carbamazepine, rats were pre-treated intraplantarlly with L-arginine (a nitric oxide precursor, 100 and 200 μg/paw), L-NAME (NOS inhibitor, 50 and 100 μg/paw), methylene blue (guanylyl cyclase inhibitor, 100 and 200 μg/paw), glibenclamide (KATP channel blocker, 100 and 200 μg/paw), and diazoxide (400 μg/paw). Moreover, to investigate the possible involvement of PPARγ receptors, pioglitazone (10 μg/paw; a PPARγ agonist) alone or in combination with GW9662 (3 μg/paw; a PPARγ antagonist) were pre-treated with carbamazepine. The local ipsilateral, but not contralateral, administration of carbamazepine into the hind paw produced dose-related analgesia during both early and late phases of formalin test. Moreover, pre-treatment with L-NAME, methylene blue, and glibenclamide dose-dependently prevented carbamazepine (300 μg/paw)-induced antinociception in both phases of the test. In addition, administration of L-arginine and diazoxide before the sub-effective dose of carbamazepine (100 μg/paw) produced an antinociceptive effect. Also, antinociception induced by carbamazepine plus pioglitazone (10 μg/paw) was blocked by GW-9662 in both phases of the test. In conclusion, carbamazepine induced a peripheral antinociceptive effect through PPARγ receptors and L-arginine/NO/cGMP/KATP channel pathway, with potential for a new topical analgesic drug.

Reduced endothelial nitric oxide synthase activation contributes to cardiovascular injury during chronic kidney disease progression.

Major cardiovascular events are a common complication in patients with chronic kidney disease (CKD). Endothelial dysfunction can contribute to the cardiovascular injury observed in CKD. Here, we used a rat model of acute kidney injury to CKD transition to investigate heart alterations in the pathway activating endothelial nitric oxide synthase (eNOS) and its impact on the cardiac injury observed during CKD progression. Fifty male Wistar rats were subjected to sham surgery (n = 25) or bilateral renal ischemia-reperfusion (IR-CKD) for 45 min (n = 25). Rats were studied on a monthly basis up to 5 mo (n = 5). In another set of sham and IR-CKD rats, l-arginine was administered starting on the third month after renal ischemia. CKD development and cardiac alterations were monitored in all groups. CKD was characterized by a progressive increase in proteinuria and renal dysfunction that was evident after the fifth month of followup. Heart hypertrophy was observed starting on the fourth month after ischemia-reperfusion. There was a significant increase in brain natriuretic peptide levels. In the heart, IR-CKD rats had increased eNOS phosphorylation at threonine 495 and reduced eNOS-heat shock protein-90α interactions. l-Arginine administration prevented the heart alterations observed during CKD and increased eNOS coupling/dimerization and activation. In summary, CKD progression is accompanied by cardiac hypertrophy, fibrosis, oxidative stress, and increased brain natriuretic peptide levels. These alterations were associated with limited eNOS activation in the heart, which may result in reduced nitric oxide bioavailability and contribute to cardiac injury during CKD.

Molecular evidence of tissue remodeling in an animal model of heart failure.

Heart failure (HF) is the final common pathway of many cardiovascular diseases. Metalloproteinases and their inhibitors, such as MMP9 and TIMP-1, assist in maintaining the extracellular matrix, leading to tissue remodeling observed after HF. Previous studies have shown that L-Arginine (LA) appears to have beneficial effects for the treatment of HF, contributing to vasodilation, the reestablishment of the endothelial function and an increase in muscle contractile force. This study analyzed heart tissue remodeling in an animal model of HF induced by aortocaval fistula (ACF) and submitted to LA treatment. After 4 weeks of ACF, animals were treated with LA for 4 weeks (SHAM-LA, HF-LA) or for 8-12 weeks with saline (SHAM, HF8, HF12). Rats were euthanized and the hearts removed for histological processing. The samples were stained with Hematoxylin-Eosin (HE), Masson's Thichome (MT), or submitted to immunohistochemistry (IHC) for MMP9 and TIMP-1. Light microscopy analysis showed cardiac striated muscle without fibrosis in all experimental groups. Immunostaining of MMP9 and TIMP-1 were positive for all experimental groups. LA administration significatively reduced MMP9 content after HF. These data indicate molecular changes in metalloproteinases expression prior to tissue remodeling and point out LA as an adjuvant therapy to pharmacological treatment of patients with HF.

Exogenous l-ARGININE does not stimulate production OF NO or cGMP within the rat corporal smooth muscle cells in culture

Background and aimNitric oxide (NO) is the intracellular chemical responsible for initiating a penile erection. Despite conflicting clinical data, it continues to be publicized and promoted that orally administered l-arginine, the putative substrate for NO, enhances the erectile response presumably by stimulating NO production by the corporal tissues resulting in an increase in cGMP production. To shed light on this issue, an in vitro study was conducted to explore the effect of direct exogenous administration of l-arginine as well as its precursor and metabolite, l-citrulline, on the NO-cGMP pathway within the cavernosal smooth muscle (CSM) cell. Materials and methodsCSM cells obtained from 8 to 10 week old Sprague-Dawley rats were grown in Dulbecco media with 20% fetal calf serum and then incubated with or without l-arginine (L-ARG) or l-citrulline (L-CIT) in a time course and dose-response manner. Sildenafil (0.4 mM), IBMX (1 mM), l-NAME (3 μM), ODQ (5 μM) and Deta Nonoate (10 μM) were used as either inhibitors or stimulators of the NO-cGMP pathway. mRNA and protein were extracted and used for the determination of the phosphodiesterase 5 (PDE5). PDE5 activity was determined by luminometry. cGMP content was determined by ELISA. Nitrite formation, an indicator of NO production, was measured in the cell culture media by a colorimetric assay. The cationic (CAT-1) and neutral (SNAT-1) amino acid transporters for L-ARG and L-CIT, respectively, were determined by Western blot. ResultsWhen compared to untreated CSM cells, incubation with 0.25–4.0 mM of L-ARG or 0.3–4.8 mM of L-CIT anywhere between 3 and 24 h did not result in any additional nitrite or cGMP production. The addition of l-NAME, IBMX or ODQ to these L-ARG and L-CIT treated cells did not alter these results. L-CIT but not L-ARG increased PDE5 mRNA and protein content as well as the activity of the PDE5 enzyme. Both CAT-1 and SNAT-1 were expressed in the CSM cells. ConclusionsThis in vitro study demonstrates that exogenous administration of L-ARG or L-CIT failed to stimulate production of either NO or cGMP by the corporal CSM cells. A re-evaluation of the presumptive role of the exogenous administration of L-ARG in improving the synthesis of NO at least at the level of the CSM cells appears warranted.

Safety and efficacy of l-arginine produced by fermentation with Corynebacteriumglutamicum KCCM 80182 for all animal species.

Following a request from the European Commission, the Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on l‐arginine produced by fermentation with a genetically modified strain of Corynebacterium glutamicum KCCM 80182 when used as a nutritional additive in feed and water for drinking for all animal species categories. Viable cells of the production strain and its recombinant DNA were not detected in the additive. The product l‐arginine, manufactured by fermentation with C. glutamicum, KCCM 80182, does not give rise to any safety concern with regard to the production strain. l‐Arginine produced using C. glutamicum KCCM 80182 is considered safe for the target species. The FEEDAP Panel has concerns regarding the safety of the simultaneous oral administration of l‐arginine via water for drinking and feed. l‐Arginine produced using C. glutamicum KCCM 80182 is safe for the consumer and for the environment. The additive is not hazardous by inhalation, is not a skin sensitiser, but is corrosive to skin and eyes. The product under assessment is considered an efficacious source of the amino acid l‐arginine for all animal species. For l‐arginine to be as efficacious in ruminants as in non‐ruminant species, it requires protection against microbial degradation in the rumen.

Extracellular l-arginine Enhances Relaxations Induced by Opening of Calcium-Activated SKCa Channels in Porcine Retinal Arteriole.

We investigated whether the substrate for nitric oxide (NO) production, extracellular l-arginine, contributes to relaxations induced by activating small (SKCa) conductance Ca2+-activated potassium channels. In endothelial cells, acetylcholine increased 3H-l-arginine uptake, while blocking the SKCa and the intermediate (IKCa) conductance Ca2+-activated potassium channels reduced l-arginine uptake. A blocker of the y+ transporter system, l-lysine also blocked 3H-l-arginine uptake. Immunostaining showed co-localization of endothelial NO synthase (eNOS), SKCa3, and the cationic amino acid transporter (CAT-1) protein of the y+ transporter system in the endothelium. An opener of SKCa channels, cyclohexyl-[2-(3,5-dimethyl-pyrazol-1-yl)-6-methyl-pyrimidin-4-yl]-amine (CyPPA) induced large currents in endothelial cells, and concentration-dependently relaxed porcine retinal arterioles. In the presence of l-arginine, concentration-response curves for CyPPA were leftward shifted, an effect unaltered in the presence of low sodium, but blocked by l-lysine in the retinal arterioles. Our findings suggest that SKCa channel activity regulates l-arginine uptake through the y+ transporter system, and we propose that in vasculature affected by endothelial dysfunction, l-arginine administration requires the targeting of additional mechanisms such as SKCa channels to restore endothelium-dependent vasodilatation.

Low dose of carvacrol prevents rat pancreas tissue damage after L-arginine application, while higher doses cause pancreatic tissue impairment

Carvacrol (5-isopropyl-2-methylphenol) is a biologically active monoterpene phenol abundantly present in the essential oils of many Lamiaceae aromatic/ethnomedicinal plants. Herein, we aimed to evaluate the damaging effect of carvacrol to rat pancreatic tissue, but also to assess its possible ameliorative impact on pancreatic damage induced by L-arginine. The toxic and beneficial (in a dose of 10 mg/kg) properties of carvacrol were assessed by measuring serum α-amylase and lipase activities, tissue malondialdehyde (MDA) content, and pathohistological changes in pancreatic tissue. Application of 100/500 mg/kg of carvacrol produced a significant increase in α-amylase activity, followed by inflammatory-cell infiltration and patchy interlobular edema in the pancreas. In the L-arginine-induced pancreatitis model, a dose of 10 mg/kg of carvacrol prevented an increase in α-amylase and lipase activities, and MDA formation, when compared to the animals that received L-arginine only. Animals treated with carvacrol prior to L-arginine administration displayed mild edema and inflammatory infiltration with few necrotic areas. Contrary to that, animals that received only L-arginine showed a massive leukocyte infiltrate with edema and substantial necrotic areas. In our study carvacrol showed significant protective effects and a potential to modulate leukocyte recruitment in pancreatic tissue after L-arginine injection.

076 Exogenous Administration of L-arginine Does Not Stimulate the Endogenous NO-cGMP Pathway in Rat Penile Corpora Smooth Muscle Cells

076 Exogenous Administration of L-arginine Does Not Stimulate the Endogenous NO-cGMP Pathway in Rat Penile Corpora Smooth Muscle Cells

Apoptosis perturbations and expression of regulatory inflammatory factors in cisplatin-depleted rat livers under l-arginine protection.

Hepatic injury is one of the most common complications associated with cisplatin (CIS) use. Recently, liver protection lines are being discovered to stop the hepatic cell death due to inflammatory and apoptotic perturbations. l-arginine has protective effects in several models of liver injury. This study was designed to investigate the possible protective effect of l-arginine against CIS-induced acute hepatic injury in rats. Rats were divided into 4 groups: control, l-arginine, CIS, l-arginine + CIS. Liver function, oxidative stress, inflammatory cytokines, and apoptosis markers were assessed. l-arginine pretreatment protected the liver against CIS-induced toxicity as indicated by significantly alleviating the changes in liver function along with restoration of the antioxidant status. This finding was confirmed with the markedly improved pathological changes. l-arginine showed anti-inflammatory effect through the reduction of liver expression of iNOS, TNF-α, and NF-κβ, which were ameliorated to significant levels. Furthermore, l-arginine administration downregulated the liver expression of the apoptotic marker, caspase-3. The results recommend l-arginine as a hepatoprotective agent against CIS toxicity. Mostly, this hepatoprotective effect of l-arginine involved anti-inflammatory and anti-apoptotic activities.