UMLS:C0011849 - FACTA Search

Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Target Concepts:

Query: UMLS:C0011849 (diabetes)
277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This work was designed to determine in vivo the influence of the metabolic control of streptozotocin-induced diabetic rats, measured by the levels of haemoglobin glycosylation in blood (HbA1c), on developing vascular endothelial dysfunction. For this, the vasoactive responses to basal and stimulated endothelial nitric oxide (NO) were studied using the technique of the anaesthetized autoperfused rat, analyzing the responses to acetylcholine (ACh) and N(G)-nitro-L-arginine methyl ester (L-NAME) in non-diabetic and diabetic rats with different degrees of metabolic control (four groups with HbA1c levels of 5.5-7.4%, 7.5-9.4%, 9.5-12%, and >12%, respectively). When administered over a noradrenaline-induced vasopressor tone, ACh (0.25, 0.75, 2.5, 7.5 and 25 microg kg(-1)) induced dose-dependent vasodilatatory responses in all rat groups, reducing both mean arterial pressure and perfusion pressure of the left hindlimb. These responses were similar in non-diabetic and in diabetic rats with good metabolic control (HbA1c 5.5-7.4%), while diabetic rats with levels of HbA1c higher than 7.5% showed significantly lower vasodilatatory responses to ACh. In untreated diabetic rats, the relaxant responses evoked by the NO donor sodium nitroprusside were also impaired. On the other hand, increasing doses of L-NAME (0.1 to 10 mg kg(-1)) enhanced both mean arterial pressure and left hindlimb perfusion pressure in diabetic and non-diabetic rats. As with ACh, the responses to L-NAME were significantly reduced in diabetic rats with HbA1c levels higher than 7.5%. To determine the mechanism underlying the NO-mediated endothelial dysfunction, the responses to ACh in untreated diabetic rats (HbA1c >12%) were studied in the presence of the NO substrate L-arginine, in the presence of the oxygen-derived free radical scavenger superoxide dismutase (SOD), or in the presence of both compounds. Both L-arginine and SOD produced a partial improvement of the ACh-induced vasodilatatory responses, but the effects of these agents were not additive. In this group of animals, SOD also induced a partial recovery of the L-NAME-evoked vasoconstrictions. In non-diabetic and untreated diabetic rats, the plasma levels of NO derivatives and arginine were measured. No significant differences were obtained in the amount of nitrites plus nitrates, while plasma levels of arginine were markedly reduced in the untreated diabetic animals. The results indicate that the endothelial dysfunction associated to diabetes is closely related to the level of metabolic control of the disease. Therefore, it is possible to establish a threshold for developing endothelium impairment from percentages of HbA1c higher than 7.5%. As the responses to the NO synthase blocker L-NAME were analogously impaired, it is reasonable to suggest that diabetic endothelial dysfunction is related to the interference with mechanisms linked both to stimulated and basal production of NO. We suggest that this interference is partially due to a deficit in the substrate availability for NO and to an increased generation of superoxide anions.
...
PMID:Impairment of nitric oxide-mediated relaxations in anaesthetized autoperfused streptozotocin-induced diabetic rats. 984 Apr 21

Severe reproductive dysfunction has been described in non-insulin-dependent diabetes mellitus (NIDDM), correlated with high glucose levels in the plasma. We have characterized an abnormal prostanoid profile in tissues from NIDDM rats, and a tight correlation between nitric oxide (NO) levels and prostaglandin production. Likewise, we have determined that parturition is delayed in NIDDM rats compared to control animals. In order to characterize the events which precede delayed parturition in NIDDM rats, we evaluate (a) the arachidonic acid (AA) conversion in placental tissue obtained from control (day 21 and 22) and NIDDM (day 21, 22 and 23) late pregnant rats into prostaglandin E2 (PGE2) and F2alpha (PGF2alpha), thromboxane B2 (TXB2) and 6-keto-prostaglandin F1alpha (6-keto-PGF1alpha), and (b) NO synthase (NOS) activity in control and NIDDM late pregnant animals. Placental arachidonate conversion from control rats into different prostanoids, namely PGE2, PGF2alpha, and TXB2, is higher in day 22 than in day 21, and radioconversion from diabetic rats into PGE2, PGF22, TXB2 and 6-keto-PGF1alpha on day 23 is higher than in day 21 and 22. 6-keto-PGF1alpha is lower and TXB2 is higher in diabetic tissues than in control. Placental AA conversion of control diabetic tissues on the day of delivery is decreased by N(G) monomethyl-L-arginine (LNMMA) (600 mM), a well known NOS inhibitor, while prostanoid production remains unaltered on previous days. NOS activity is higher in control on day 22 when compared to day 21, and in diabetic on day 23 when compared to day 22 of pregnancy. We conclude that elevated NO placental levels are observed in control (day 22) and NIDDM (day 23) rats, and may increase placental prostaglandin production on the day of delivery.
...
PMID:Nitric oxide modulates placental prostanoid production from late pregnant non-insulin-dependent diabetic rat. 988 3

Inflammatory mechanisms are involved in the pathophysiology of cardiovascular disease and the present review focus us on the association between inflammation and microvascular endothelial dysfunction in the heart, i.e. reduced endothelium dependent vasodilation of coronary resistance vessels. This abnormality is caused by reduced bioactivity of nitric oxide (NO), and it is found in a variety of conditions, including ischemic heart disease, cardiac allograft vasculopathy, diabetes, hypercholesterolemia, and smoking. At the level of the myocardial microcirculation, reperfusion injury manifests itself as endothelial dysfunction, no-reflow, and increased permeability, which are all probably the result of reperfusion-induced augmentation of the inflammatory response. In other animal models of cardiovascular disease, inflammatory alterations have been described that can contribute to microvascular endothelial dysfunction and reactive oxygen species, neutrophils, tumour necrosis factor-alpha, and inducible NO synthase are among the mediators that have been incriminated. Circulating levels of inflammatory mediators may serve as molecular markers of cardiovascular disease, and antiinflammatory interventions hold some promise for future cardiovascular therapy.
...
PMID:Inflammatory alterations in the myocardial microcirculation. 999 May 27

The excessive production of nitric oxide (NO) and the subsequent increase of local oxidative stress is suggested as one of the pathophysiological mechanisms of streptozotocin-induced diabetes. It was reported that the administration of NO synthase inhibitors partially attenuated the development of streptozotocin-induced diabetes and reduced hyperglycaemia. Here we have studied the influence of methylene blue, which combines the properties of NO synthase inhibitor with antioxidant effects. The experiments were performed on male rats divided into four groups: control, diabetic (single dose of 70 mg of streptozotocin/kg i.p.), methylene blue (50 mg/kg in the food) and diabetic simultaneously fed with methylene blue. After 45 days the experiments were discontinued by decapitation. Serum glycaemia, glycated haemoglobin and oxidative stress parameters (plasma malondialdehyde concentration and erythrocyte superoxide dismutase activity) were significantly higher in the diabetic group. Simultaneous methylene blue administration partially reduced glycaemia and glycated haemoglobin, but did not decrease oxidative stress. We conclude that NO synthase inhibitor methylene blue partially attenuates the development of streptozotocin-induced diabetes in male rats, but does not reduce the development of oxidative stress in the diabetic group.
...
PMID:The influence of NO synthase inhibitor and free oxygen radicals scavenger--methylene blue--on streptozotocin-induced diabetes in rats. 1005 1

The purpose of this investigation was to study the time course, response to insulin and characteristics of erectile dysfunction in streptozotocin (STZ)-diabetic Sprague-Dawley rats, and the function of the NO-generating system in these animals. Copulation-induced and reflex erection were quantified in conscious Sprague-Dawley rats at different times after injection of STZ. The corporal vasodilatation response to nerve stimulation was studied by measuring the rise in corporal pressure in pithed rats following electrical stimulation of sacral spinal nerve roots. The activity of NO synthase was determined in corporal tissue by measuring the generation of [3H]citrulline from [3H]arginine. Copulation-induced erection was inhibited at 1 and 2 months after STZ treatment, but this could be prevented by a short (2-week) pretreatment with insulin. Reflex erection was inhibited at 1, 4, 6 and 9 months after STZ; at 6 months, this inhibition was also reversible by insulin pretreatment. Following pithing, the basal corporal pressure was elevated in diabetic rats. At 4 months after STZ, this increase was normalized by a 2-week, but not by a 1-week, pretreatment with insulin; however, at 9 months after STZ, insulin pretreatment did not normalize corporal pressure. The increase in corporal pressure caused by stimulation of sacral nerve roots in pithed rats was enhanced in diabetic animals. This enhancement was also normalized at 4 months, but not at 9 months, by 2 weeks of insulin treatment. The inhibition of the stimulation-induced increase in corporal pressure by NG-nitro-L-arginine methyl ester (5 mg/kg) was less following 9 months of diabetes, although NO synthase activity was normal in cavernosal tissue following 6-8 months of diabetes. In conclusion, STZ-induced diabetes caused changes in the erectile system that were initially reversible by a short insulin treatment, but which with time (more than 6 months) became irreversible. NO synthase activity in cavernosal tissue was normal, but the response to NG-nitro-L-arginine methyl ester was inhibited in long-term diabetes (9 months).
...
PMID:Nitric oxide and penile erection in streptozotocin-diabetic rats. 1008 43

It has been reported that insulin treatment improves hypertension in patients with diabetes mellitus. The mechanisms of the antihypertensive effect of insulin, however, remain to be fully elucidated. In the present study, we investigated a possible involvement of nitric oxide (NO) in insulin-induced reduction of blood pressure using the Zucker diabetic fatty (ZDF) rat, an animal model of non-insulin-dependent diabetes mellitus. The animals were divided into three groups and treated for 4 weeks with daily subcutaneous injections of insulin (25U/kg body weight) with or without oral administration of l-nitro-arginine methyl ester (L-NAME, 50mg/kg/day body weight as drinking water), an inhibitor of NO synthase (NOS). Saline solution was injected subcutaneously in the control groups. During the experimental period, body weight gain was greater in the insulin-treated groups than in the control groups whereas water intake was considerably decreased in the insulin-treated groups. Insulin treatment resulted in a decrease in plasma glucose and blood pressure, and an increase in both NO metabolites (NOx) in the plasma and NOS activity in the aorta tissue. L-NAME treatment blunted not only the antihypertensive effect of insulin but also the changes in NOx and NOS activity. These findings suggest that insulin reduces blood pressure in the ZDF rat by stimulating NOS activation and NO production.
...
PMID:Antihypertensive effect of insulin via nitric oxide production in the Zucker diabetic fatty rat, an animal model for non-insulin-dependent diabetes mellitus. 1009 54

We tested the hypothesis that pregnancy might increase diabetes-associated nitric oxide (NO) production and renal hyperfiltration. Two weeks following i.v. streptozotocin (40 mg/kg), mean arterial pressure (MAP) was not modified by diabetes; glomerular filtration rate (GFR), renal plasma flow (RPF) and filtration fraction (FF) were higher in pregnant than in virgin controls and increased by diabetes to a greater extent in pregnant than in virgin rats. Urinary volume (UV), creatinine, albumin and sodium (UNaV) were significantly increased by diabetes. Diabetes led to an increase in renal, cardiac, aortic and uterine but not in placental NO synthase activities. Infusion of NG-nitro-l-arginine (l-NA) caused a dose-dependent reduction in GFR, RPF, plasma NO2-/NO3-, UV and UNaV; in general, diabetes increased these effects to a greater extent in pregnant than in virgin rats. l-NA increased MAP in all groups of rats but did not alter FF. Diabetes did not alter responses of thoracic aorta rings to vasoconstrictor effects of phenylephrine and the vasorelaxant effects of sodium nitroprusside but increased endothelium-dependent relaxant effects of acetylcholine. In general the effects of diabetes of 7 days duration were similar to those described above for diabetes of 14 days duration. These data suggest that diabetes-associated renal hyperfiltration and NO production are augmented by pregnancy.
...
PMID:Augmentation of diabetes-associated renal hyperfiltration and nitric oxide production by pregnancy in rats. 1019 24

We have recently reported that steady-state gastric mucosal blood flow (GMBF) is decreased in streptozotocin (STZ) diabetic rats, and that their GMBF response to burn-stress is impaired, probably via a nitric oxide (NO)-mediated mechanism. Accordingly, this study was designed to investigate the relation of aldose reductase (AR) and NO synthase to the regulation of GMBF during chronic hyperglycemia. STZ rats were treated with or without chronic oral administration of an AR inhibitor, epalrestat (EPA) and/or an NO synthase inhibitor, N-nitro-L-arginine methyl ester (L-NAME). GMBF was measured by laser-Doppler velocimetry (LDV). In the STZ rats, GMBF after a 24-h fasting period was decreased significantly 4 weeks after the onset of diabetes and this was accompanied by an increase in the gastric ulcer index (UI) (a measure of the length of gastric erosions and ulcers). Chronic oral administration of EPA to the STZ rats dose-dependently inhibited the increased UI and the decreased GMBF after the fasting stress, whereas chronic oral administration of L-NAME further increased the UI and further decreased the GMBF. EPA administered in combination with L-NAME to the STZ rats reduced the effects of L-NAME, but the effects did not reach significance. These results suggest that EPA protects the gastric mucosa of diabetic rats, by preventing the decrease in GMBF that is, at least in part, caused by NO-related mechanisms.
...
PMID:Epalrestat prevents the decrease in gastric mucosal blood flow and protects the gastric mucosa in streptozotocin diabetic rats. 1021 35

Functional studies have revealed diabetes specifically impairs smooth muscle reactivity to nitric oxide in the rat anococcygeus muscle. The present study was conducted to examine whether concurrent prejunctional defects in nitrergic neurotransmission exist in anococcygeus muscles from diabetic rats. Nitric oxide synthase (NOS) activity was assessed by the conversion of 3H-L-arginine to 3H-L-citrulline in homogenates of anococcygeus muscles obtained from 8-week diabetic rats and control rats. NOS activity measured in all tissue samples was dependent on the presence of calcium (2 mM), NADPH (1 mM), tetrahydrobiopterin (100 microM) and flavin adenine dinucleotide (10 microM); however, removal of calmodulin (50 U/ml) did not reduce L-citrulline production. Both N(G)-nitro-L-arginine (100 microM) and N(G)-nitro-L-arginine methyl ester (100 microM) produced significant inhibition of enzyme activity. NOS activity measured in tissue samples from diabetic rats (369.6 +/- 75.9 fmol L-citrulline/mg protein) did not significantly differ from that measured in samples from control rats (423.9 +/- 110.6 fmol L-citrulline/mg protein). However, NOS activity measured after removal of the cofactor tetrahydrobiopterin, was significantly greater in samples from control rats than that from the diabetic group. NOS-immunoreactive and NADPH-diaphorase reactive nerve terminals were found to be sparsely distributed throughout longitudinal sections or whole mounts of anococcygeus muscles from both control and diabetic rats. Quantification of NADPH-diaphorase positive fibres intersecting transects of whole tissue mounts, revealed no significant difference in fibre number between the treatment groups. All NOS-immunoreactive fibres also showed vasoactive-intestinal-polypeptide immunoreactivity. In conclusion, the findings together provide no evidence to indicate that diabetes can induce prejunctional changes in NOS activity or localisation, concurrent with the reported postjunctional impairment in smooth muscle reactivity to nitric oxide, in the rat anococcygeus muscle.
...
PMID:Diabetes does not alter the activity and localisation of nitric oxide synthase in the rat anococcygeus muscle. 1032 5

The pathogenesis of diabetic neuropathy remains unclear, although several factors have been implicated in its pathogenesis. We have examined possible roles of decreased production of nitric oxide, ion channel dysfunction and decreased capacity of nerve regeneration. STZ-induced diabetic rats showed decreases in nociceptive threshold and NADPH-diaphorase positive neurons, nNOS level and cGMP content of DRG at 12 weeks after induction of diabetes. The rats injected by L-NAME, potent nNOS inhibitor, showed decreased nociceptive threshold, although D-NAME, inactive in nNOS inhibition, did not. These results suggest that decreased NO production might be involved in hyperalgesia in diabetic rats. Both hyperglycemia and decreased Na/K-ATPase activity are thought to be characteristic features of diabetic neuropathy. To investigate the presence of ion channel abnormality in diabetic nerves, a Vaseline-gap voltage clamp technique was applied for a single myelinated fibers under 30 mM high glucose plus 0.1 mM ouabain. Since K current was increased, a Ca activated K channel blocker was applied and this increase was shown to be suppressed. Furthermore, Ca channel blockers all suppressed increased K currents, suggesting that the condition induced an increase of Ca influx, thereby increasing Ca activated K currents through K channels. The data are important in that diabetic condition may induce both Ca influx, leading to nerve degeneration, and increased K current, resulting in decreased nerve conduction. Nerve regeneration has been known to be disturbed in diabetic condition. We have shown a decrease in nerve elongation rate in diabetic rats after crush of sciatic nerve, although this decrease was not ameliorated by ARI. Furthermore, Wallerian degeneration was shown to be delayed in diabetic nerves, leading to delayed nerve regeneration. Hyperphosphorylation of both medium and high molecular weight neurofilaments that might be induced by protein kinases including CDK 5 may be involved in the mechanism.
...
PMID:[New trend in pathogenesis of diabetic neuropathy]. 1037 17

<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>