title: Effect of chronic and selective endothelin receptor antagonism on microvascular function in type 2 diabetes.
abstract: Vascular dysfunction, which presents either as an increased response to vasoconstrictors or an impaired relaxation to dilator agents, results in worsened cardiovascular outcomes in diabetes. We have established that the mesenteric circulation in Type 2 diabetes is hyperreactive to the potent vasoconstrictor endothelin-1 (ET-1) and displays increased nitric oxide-dependent vasodilation. The current study examined the individual and/or the relative roles of the ET receptors governing vascular function in the Goto-Kakizaki rat, a mildly hyperglycemic, normotensive, and nonobese model of Type 2 diabetes. Diabetic and control rats received an antagonist to either the ET type A (ETA; atrasentan; 5 mg x kg(-1) x day(-1)) or type B (ET(B); A-192621; 15 or 30 mg x kg(-1) x day(-1)) receptors for 4 wk. Third-order mesenteric arteries were isolated, and vascular function was assessed with a wire myograph. Maximum response to ET-1 was increased in diabetes and attenuated by ETA antagonism. ETB blockade with 15 mg/kg A-192621 augmented vasoconstriction in controls, whereas it had no further effect on ET-1 hyperreactivity in diabetes. The higher dose of A-192621 showed an ETA-like effect and decreased vasoconstriction in diabetes. Maximum relaxation to acetylcholine (ACh) was similar across groups and treatments. ETB antagonism at either dose had no effect on vasorelaxation in control rats, whereas in diabetes the dose-response curve to ACh was shifted to the right, indicating a decreased relaxation at 15 mg/kg A-192621. These results suggest that ETA receptor blockade attenuates vascular dysfunction and that ETB receptor antagonism exhibits differential effects depending on the dose of the antagonists and the disease state.
authors.affiliation: Program in Clinical and Experimental Therapeutics, University of Georgia College of Pharmacy, Medical College of Georgia, Augusta, Georgia, USA.
authors.forename: Kamakshi
authors.initials: K
authors.lastname: Sachidanandam
authors.forename: Mostafa M
authors.initials: MM
authors.lastname: Elgebaly
authors.forename: Alex K
authors.initials: AK
authors.lastname: Harris
authors.forename: Jim R
authors.initials: JR
authors.lastname: Hutchinson
authors.forename: Erin M
authors.initials: EM
authors.lastname: Mezzetti
authors.forename: Vera
authors.initials: V
authors.lastname: Portik-Dobos
authors.forename: Adviye
authors.initials: A
authors.lastname: Ergul
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D000077868:Atrasentan; D002317:Cardiovascular Agents / Q000494:pharmacology*; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D003925:Diabetic Angiopathies / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology / Q000517:prevention & control*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D065130:Endothelin A Receptor Antagonists; D065131:Endothelin B Receptor Antagonists; D019332:Endothelin-1 / Q000378:metabolism; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects / Q000378:metabolism; D008833:Microcirculation / Q000187:drug effects / Q000378:metabolism; D009213:Myography; D010456:Peptides, Cyclic / Q000494:pharmacology; D011759:Pyrrolidines / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D044022:Receptor, Endothelin A / Q000378:metabolism; D044023:Receptor, Endothelin B / Q000378:metabolism; D015854:Up-Regulation; D014661:Vasoconstriction / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology; D014757:Viper Venoms / Q000494:pharmacology
chemical_list: C120508:A 192621; D002317:Cardiovascular Agents; D065130:Endothelin A Receptor Antagonists; D065131:Endothelin B Receptor Antagonists; D019332:Endothelin-1; D010456:Peptides, Cyclic; D011759:Pyrrolidines; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D014757:Viper Venoms; C057354:sarafotoxins s6; D000109:Acetylcholine; C072247:cyclo(Trp-Asp-Pro-Val-Leu); D000077868:Atrasentan