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Elevated Epidermal Growth Factor Receptor Phosphorylation Induces Resistance Artery Dysfunction in Diabetic db/db mice

¹Department of Physiology, LSU Health Sciences Center, 1901 Perdido Street, New Orleans LA 70112
²Department of Pharmacology, LSU Health Sciences Center, 1901 Perdido Street, New Orleans LA 70112
³Department of Physiology, Tulane University, 1430 Tulane Ave, New Orleans LA 70112, and Hypertension and Renal Biology Center of Excellence

Objective: We previously showed epidermal growth factor receptor (EGFR) transactivation as key mechanism in the regulation of resistance artery myogenic tone. Type 2 diabetes is associated with microvascular complications. We hypothesized that elevated EGFR phosphorylation contributes to resistance artery dysfunction in type 2 diabetes.

Methods-Results: Diabetic db/db (diabetic) and non-diabetic (control) mice were treated with EGFR inhibitor (AG1478, 10 mg/kg/day) for 2 weeks. Isolated coronary artery (CA) and mesenteric resistance artery (MRA) were mounted in an arteriograph. Pressure-induced myogenic tone (MT) was increased in MRA and CA from diabetic mice and normalized by AG1478. Phenylephrine-induced contraction and nitric oxide donor-induced relaxation were similar in all groups. Relaxation endothelium-dependent in response to shear-stress and acetylcholine of MRA and CA from diabetic mice were altered and associated with reduced eNOS expression and phosphorylation. Treated diabetic mice with AG1478 improved CA and MRA endothelial function and restored eNOS expression. Immunostaining and western blot analysis showed increased endothelial and SMC EGFR phosphorylation of MRA and coronary from diabetic mouse, which was reduced by AG1478.

Primary cultured endothelial cells (EC), from resistance arteries, treated with high glucose for 48hrs showed an increase of EGFR phosphorylation associated with eNOS expression and phosphorylation decrease in response to calcium ionophore. Pretreatment of endothelial cells with AG1478 prevented the effect of high glucose.

Conclusion: This study provides evidence of the role of elevated EGFR phosphorylation in CA and MRA dysfunction in diabetic db/db mice. Therefore, EGFR should be a potential target for overcoming diabetic small arteries complications.

Key Words: resistance artery • myogenic tone • flow-induced dilation • eNOS • EGF receptor • Type 2 diabetes, and • diabetic db/db mice

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