Correction of endothelial dysfunction in diabetic female rats by tetrahydrobiopterin and chronic insulin.

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Akamine EH, Kawamoto EM, Scavone C, Nigro D, Carvalho MH, de Cassia A Tostes R, Britto LR, Fortes ZB

Correction of endothelial dysfunction in diabetic female rats by tetrahydrobiopterin and chronic insulin.

J Vasc Res. 2006;43(4):309-20. Epub 2006 May 8.

PubMed ID

16682803 [ View in PubMed

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Abstract

Diabetes-induced vascular dysfunction has mainly been studied in males. However, the mechanisms involved may not correspond to those in females. Here we analyzed the effects of tetrahydrobiopterin (BH(4)) and chronic insulin on the physiology of mesenteric arterioles of alloxan-diabetic female rats. The parameters studied were the mesenteric arteriolar reactivity (intravital microscopy), nitric oxide synthase (NOS) activity (conversion of L-arginine to L-citrulline), eNOS gene expression (RT-PCR), NO production (diaminofluorescein), reactive oxygen species (ROS) generation (intravital fluorescence microscopy) and Cu/Zn superoxide dismutase (SOD) activity (spectrophotometry) and gene expression (RT-PCR). The reduced endothelium-dependent vasodilation of diabetic females was corrected by both BH(4) and insulin. NOS activity was decreased by diabetes, but insulin did not correct it. However, NOS expression was not modified by either diabetes or insulin. Arterioles of diabetic rats exhibited lower NO production, which was fully corrected by BH(4) and only partially by insulin. ROS generation was increased in diabetic rats, and both BH(4) and insulin normalized it. Diabetes did not change SOD activity and gene expression. However, insulin increased SOD activity but not its expression. Our data suggest that, similarly to males, endothelial dysfunction in female diabetic rats involves an altered ROS/NO imbalance. In contrast to males, however, insulin does not regulate NOS in the microcirculation of diabetic females.

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Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Arginine	Nitric oxide synthase, endothelial	Protein	Humans	Unknown	Not Available	Details