nitroarginine and Diabetes-Mellitus

An enhanced vasocontrictor activity of cutaneous vessels participates in the reduction of skin blood flow induced by cooling. The present study investigated changes in the local response to cooling in hyperglycemic conditions. Male diabetic db/db and control C57BL/6J mice, anaesthetized with pentobarbitone, were treated with tetrodotoxin for eliminating the sympathetic nerve tone and artificially ventilated. The plantar skin blood flow (PSBF) was measured by laser Doppler flowmetry. Cooling the air temperature around the foot reduced PSBF in a temperature-dependent manner in control and db/db mice. The PSBF reduction was significantly smaller in db/db mice than in control mice. Phentolamine, a non-selective α-antagonist, bunazosin, a selective α1-antagonist, MK-912, a selective α2C-antagonist, and Y-27632, a Rho-kinase inhibitor, significantly inhibited the PSBF reduction induced by cooling to 15 °C in both mice and the inhibitory effects were comparable between these mice. The cooling-induced PSBF reduction was also significantly inhibited by N(ω)-nitro-L-arginine, an inhibitor of nitric oxide synthase, in control mice; however, the inhibitory effect of N(ω)-nitro-L-arginine was not observed in db/db mice. The reduction of PSBF induced by the intraarterial administration of adrenaline was comparable between control and db/db mice both before and after the treatment with N(ω)-nitro-L-arginine. It is thus likely that the reduction of skin blood flow induced by local cooling might be partly mediated by a decrease in endothelium-derived nitric oxide production, and that an impairment of the nitric oxide production might be related to reduced vasocontrictor response to cooling in db/db mice.

Topics: Adrenergic alpha-Antagonists; Amides; Animals; Cold Temperature; Diabetes Mellitus; Male; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Nitric Oxide; Nitric Oxide Synthase; Nitroarginine; Protein Kinase Inhibitors; Pyridines; Regional Blood Flow; rho-Associated Kinases; Skin; Skin Temperature

Pressure-induced vasodilation (PIV) allows skin blood flow to increase in response to locally applied pressure and may be protective against pressure ulcers. We previously showed that PIV was absent in 1-week diabetic mice exhibiting no neuropathy. Our aim was to determine whether the diabetes-induced PIV alteration could be prevented.. Diabetic mice received no treatment or a daily treatment with either sorbinil, alagebrium or alpha-lipoic acid (LPA) for 1 week. Laser Doppler flowmetry was used to evaluate PIV as well as endothelium-dependent vasodilation following iontophoretic delivery of acetylcholine (ACh). The effect of each treatment on oxidative stress was examined by plasma 8-isoprostane assay. LPA was the sole treatment to prevent both PIV and ACh vasodilation alterations, with a significant reduction of oxidative stress in diabetic mice. Both PIV and ACh-vasodilation were abolished in LPA-treated diabetic mice following injection of Nomega-nitro-L-arginine (p<0.05). In contrast, alagebrium and sorbinil prevented neither diabetes-induced PIV abolition nor endothelial alteration.. LPA treatment significantly reduced the oxidative stress and was able to preserve endothelial nitric oxide availability in the cutaneous microcirculation and then to preserve the PIV response in diabetic mice. LPA treatment could play a key role in limiting the risk of pressure-induced cutaneous ulcer during diabetes.

Topics: Acetylcholine; Aldehyde Reductase; Animals; Antioxidants; Biomarkers; Diabetes Mellitus; Dinoprost; Imidazolidines; Laser-Doppler Flowmetry; Male; Mice; Microcirculation; Nitric Oxide Synthase; Nitroarginine; Oxidative Stress; Pressure; Pressure Ulcer; Regional Blood Flow; Skin; Thioctic Acid; Vasodilation; Vasodilator Agents

Microparticles (MPs) are membrane vesicles with procoagulant and proinflammatory properties released during cell activation. The present study was designed to dissect the effects evoked by T lymphocyte-derived MPs on vascular function.. MPs were produced by treatment of the human lymphoid CEM T cell line with actinomycin D or phytohemagglutinin. Incubation of mouse aortic rings with 30 nmol/L MPs resulted in a time-dependent impairment of acetylcholine-induced relaxation of precontracted vessels, with a maximal reduction after 24 hours. MPs also impaired shear stress-induced dilatation of mouse small mesenteric arteries by affecting the nitric oxide (NO) and prostacyclin but not the endothelium-derived hyperpolarizing factor components of the response. However, neither alteration of calcium signaling in response to agonists nor reduction of cyclooxygenase-1 expression accounted for the impairment of the NO and prostacyclin components of the endothelial response. The effect of MPs was rather because of a decrease in expression of endothelial NO synthase and an overexpression of caveolin-1. Furthermore, lymphocyte-derived MPs from diabetic patients or in vivo circulating MPs from either diabetic or HIV-infected patients reduced endothelial NO synthase expression. Finally, the effects of MPs on endothelial cells were not driven through CD11a/CD18 adhesion molecules or the Fas/FasL pathway.. MPs from T cells induce endothelial dysfunction in both conductance and resistance arteries by alteration of NO and prostacyclin pathways. MPs regulate protein expression for endothelial NO synthase and caveolin-1. These data contribute to a better understanding of the deleterious effects of enhanced circulating MPs observed in disorders with cardiovascular or immune complications.

Topics: Acetylcholine; Animals; Aorta; Biological Factors; Caveolin 1; Caveolins; Cell Membrane; Cells, Cultured; Dactinomycin; Diabetes Mellitus; Endothelial Cells; Endothelium, Vascular; Gene Expression Regulation; HIV Infections; Humans; In Vitro Techniques; Male; Membrane Lipids; Mesenteric Arteries; Mice; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Nitroarginine; Phosphatidylserines; Phytohemagglutinins; Prostaglandins I; Stress, Mechanical; T-Lymphocytes; Vasodilation

This study investigated the influence of superoxide anion on the norepinephrine (NE)-induced contractile response in spontaneously diabetic mice. In aortic rings with intact endothelium, NE elicited only a slight increase in tension in nondiabetic mice (db/+M), but a much greater dose-dependent contraction in spontaneously diabetic mice (db/db mice). The NE-induced contractile response was significantly reduced by pretreatment with SOD (180 U/ml) in diabetic mice, but not in control mice. The NE-induced contraction was significantly enhanced by pretreatment with diethyldithiocarbamic acid (DETCA, 10(-3) M), a Cu/Zn SOD inhibitor, in control mice, but not in diabetic mice. The dose-response curve for the acetylcholine-induced relaxation was slightly, but significantly attenuated in diabetic mice. When aortic rings from control mice were incubated with a mixture of hypoxanthine (10(-5) M), xanthine oxidase (0.1 U/ml) and catalase (1000 U/ml) in control mice, they gradually contracted. This contraction was abolished by pretreatment with SOD (180 U/ml) or indomethacin (10(-5) M) or by removal of the endothelium. The enhanced NE-induced dose-dependent contraction seen in diabetic mice was markedly attenuated by indomethacin. These results suggest that in db/db diabetic mice, superoxide anion, perhaps via vasoconstrictor prostanoids, may enhance the contraction induced by NE.

Topics: Acetylcholine; Animals; Anti-Inflammatory Agents, Non-Steroidal; Aorta, Thoracic; Blood Glucose; Body Weight; Diabetes Mellitus; Dose-Response Relationship, Drug; Enzyme Inhibitors; In Vitro Techniques; Indomethacin; Insulin; Isometric Contraction; Male; Mice; Mice, Inbred C57BL; Muscle Contraction; Muscle Tonus; Muscle, Smooth, Vascular; Nitric Oxide Synthase; Nitroarginine; Norepinephrine; Potassium; Superoxide Dismutase; Superoxides; Vasoconstrictor Agents; Vasodilator Agents

This study was performed to investigate the mechanism for impaired vasodilation in response to activated diabetic human platelets. As observed previously, diabetic platelets failed to cause vasorelaxation, whereas normal platelets produced normal vasodilation. However, when activated and perfused through quiescent, NG-nitro-L-arginine-pretreated arteries, diabetic and normal platelets caused similar degrees of vasoconstriction. Inhibition of serotonergic and thromboxane A2 receptors in preconstricted normal arteries also failed to improve vasodilatory responses to diabetic platelets. The amount of ADP released into the supernatant from activated diabetic and normal platelets was similar. Concomitant perfusion of activated diabetic platelets impaired vasodilation produced by abluminally applied acetylcholine but perfusion of normal platelets did not. Whereas activated diabetic platelets failed to produce vasodilation, supernatant from the same platelets caused normal vasorelaxation. Dimethylthiourea and Tiron, intracellular free radical scavengers, normalized the vasodilatory response to diabetic platelets, whereas superoxide dismutase, catalase, and mannitol did not. We conclude that the impaired vasorelaxation in response to activated diabetic platelets is caused by an unidentified, short-acting, platelet-derived substance(s) that interferes with the normal dilatory response.

Topics: Acetylcholine; Adolescent; Adult; Animals; Blood Platelets; Carotid Artery, Common; Cell Communication; Diabetes Mellitus; Diabetes Mellitus, Type 1; Diabetes Mellitus, Type 2; Endothelium, Vascular; Female; Humans; In Vitro Techniques; Male; Middle Aged; Muscle, Smooth, Vascular; Nitroarginine; Perfusion; Platelet Activation; Rabbits; Reference Values; Thrombin; Vasoconstriction; Vasodilation

Interleukin-1 beta has been implicated as a pathogenic factor in the development of autoimmune thyroiditis. When given for 5 days to normal non-diabetes-prone Wistar Kyoto rats, it decreased plasma concentrations of total tri-iodothyronine and thyroxine and increased plasma TSH. These effects were not prevented by co-injection of nitroarginine methyl ester or aminoguanidine, inhibitors of NO synthases. Exposure to interleukin-1 beta dose-dependently reduced iodine uptake in FRTL-5 cells, but had no effect on thyroglobulin secretion. Nitrite was not detected in the FRTL-5 cell culture media after exposure to interleukin-1 beta. However, reverse transcription PCR analysis of mRNA isolated from interleukin-1 beta-exposed FRTL-5 cells revealed a transitory expression of the inducible NO synthase, which was markedly lower than inducible NO synthase induction in interleukin-1 beta-exposed isolated rat islets of Langerhans. Co-incubation with the NO synthase inhibitor NG-monomethylarginine did not ameliorate the effect of interleukin-1 beta on FRTL-5 cell iodine uptake. Furthermore, we demonstrate that daily injections of interleukin-1 beta for 13 weeks aggravated spontaneous thyroiditis and induced severe hypothyroidism in non-diabetic diabetes-prone BB rats. The data suggest that NO does not mediate interleukin-1 beta-induced inhibition of rat thyroid function in vivo or in vitro in FRTL-5 cells, and the induction of hypothyroidism by interleukin-1 beta in diabetes-prone BB rats is speculated to be due to exacerbation of recruitment and activation of intrathyroidal mononuclear cells.

Topics: Animals; Cell Line; Cells, Cultured; Diabetes Mellitus; Hypothyroidism; Interleukin-1; Male; Nitric Oxide; Nitric Oxide Synthase; Nitroarginine; Rats; Rats, Brattleboro; Rats, Inbred WKY; Recombinant Proteins; RNA, Messenger; Thyroid Gland; Thyroiditis