Testosterone propionate and arginase activity in diabetic rats

The assay conditions needed to achieve maximal activity of liver and kidney arginase in diabetic and non-diabetic rats were investigated and compared. The physicochemical and kinetic properties of liver arginase in diabetic and control rats were very similar, those of kidney arginase were significantly different. It was found that preincubation temperature (68°C), preincubation period (20 min), optimum pH (10.1) of liver arginase and Km (3.2) for its substrate, L-arginine, did not change in diabetic and non-diabetic rats. As a consequence of diabetes, the optimum Mn2+ concentration for liver arginase only changed from 1 to 2 mM. Although the preincubation temperature and period for activation of kidney arginase in control rats was unnecessary, they were found to be 56ºC and 12 min in diabetic rats. The pH profile of arginase in kidney of diabetic rats was different from that of control rats. The Km value (6.7) of arginase for L-arginine in kidney is unchanged in diabetes whereas a marked decrease in Vmax was found. Optimum Mn2+ concentration (2 mM) for kidney arginase was unchanged in diabetes. The activity of arginase in liver of diabetic animals was higher 1.5 to 1.7 times than that of controls. Diabetes caused an about 53% decrease of arginase activity in kidney of female rats, 26% in that of males. These findings may suggest an idea that encoded arginases by separate gene loci may be affected differently by the pathological and hormonal status.

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Inhibition of Rho kinase protects from ischaemia–reperfusion injury via regulation of arginase activity and nitric oxide synthase in type 1 diabetes

Diabetes and Vascular Disease Research ◽

10.1177/1479164116687935 ◽

2017 ◽

Vol 14 (3) ◽

pp. 236-245 ◽

Cited By ~ 7

Author(s):

Yahor Tratsiakovich ◽

Attila Kiss ◽

Adrian T Gonon ◽

Jiangning Yang ◽

Per-Ove Sjöquist ◽

...

Keyword(s):

Nitric Oxide ◽

Type 1 Diabetes ◽

Nitric Oxide Synthase ◽

Reperfusion Injury ◽

Diabetic Rats ◽

Arginase Activity ◽

Ischaemia Reperfusion Injury ◽

Ischaemia Reperfusion ◽

Oxide Synthase

Aim: RhoA/Rho-associated kinase and arginase are implicated in vascular complications in diabetes. This study investigated whether RhoA/Rho-associated kinase and arginase inhibition protect from myocardial ischaemia–reperfusion injury in type 1 diabetes and the mechanisms behind these effects. Methods: Rats with streptozotocin-induced type 1 diabetes and non-diabetic rats were subjected to 30 min myocardial ischaemia and 2 h reperfusion after being randomized to treatment with (1) saline, (2) RhoA/Rho-associated kinase inhibitor hydroxyfasudil, (3) nitric oxide synthase inhibitor NG-monomethyl-l-arginine monoacetate followed by hydroxyfasudil, (4) arginase inhibitor N-omega-hydroxy-nor-l-arginine, (5) NG-monomethyl-l-arginine monoacetate followed by N-omega-hydroxy-nor-l-arginine or (6) NG-monomethyl-l-arginine monoacetate given intravenous before ischaemia. Results: Myocardial arginase activity, arginase 2 expression and RhoA/Rho-associated kinase activity were increased in type 1 diabetes ( p < 0.05). RhoA/Rho-associated kinase inhibition and arginase inhibition significantly reduced infarct size in diabetic and non-diabetic rats ( p < 0.001). The cardioprotective effects of hydroxyfasudil and N-omega-hydroxy-nor-l-arginine in diabetes were abolished by nitric oxide synthase inhibition. RhoA/Rho-associated kinase inhibition attenuated myocardial arginase activity in diabetic rats via a nitric oxide synthase–dependent mechanism. Conclusion: Inhibition of either RhoA/Rho-associated kinase or arginase protects from ischaemia–reperfusion injury in rats with type 1 diabetes via a nitric oxide synthase–dependent pathway. These results suggest that inhibition of RhoA/Rho-associated kinase and arginase constitutes a potential therapeutic strategy to protect the diabetic heart against ischaemia–reperfusion injury.

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Sites of Insulin Action Using Ferritin Labeling

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100066759 ◽

1971 ◽

Vol 29 ◽

pp. 540-541

Author(s):

Burton B. Silver ◽

Ronald S. Nelson

Keyword(s):

Electron Microscopy ◽

Binding Sites ◽

Anterior Pituitary ◽

Insulin Action ◽

Diabetic Rats ◽

Insulin Antibody ◽

Fat Pad ◽

Target Organs ◽

Uranium Salts ◽

Sugar Levels

Some investigators feel that insulin does not enter cells but exerts its influence in some manner on the cell surface. Ferritin labeling of insulin and insulin antibody was used to determine if binding sites of insulin to specific target organs could be seen with electron microscopy.Alloxanized rats were considered diabetic if blood sugar levels were in excess of 300 mg %. Test reagents included ferritin, ferritin labeled insulin, and ferritin labeled insulin antibody. Target organs examined were were diaphragm, kidney, gastrocnemius, fat pad, liver and anterior pituitary. Reagents were administered through the left common carotid. Survival time was at least one hour in test animals. Tissue incubation studies were also done in normal as well as diabetic rats. Specimens were fixed in gluteraldehyde and osmium followed by staining with lead and uranium salts. Some tissues were not stained.

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