Cardioprotective effects of atrasentan, an endothelin-A receptor antagonist, but not of nitric oxide in diabetic mice with myocyte-specific overexpression of endothelial nitric oxide synthase.
1. We investigated the roles of nitric oxide (NO) and endothelin-1 (ET-1) in organ dysfunction in diabetic mice with normal genotype (wild-type, WT) or myocyte-specific overexpression of endothelial NO synthase (eNOS) (transgenic, TG) after chronic oral treatment with the endothelin-A (ETA) receptor antagonist atrasentan. 2. Mice were rendered diabetic by injection of 200 mg kg-1 streptozotocin (STZ). Experimental groups were: untreated WT diabetic (n=9), untreated TG diabetic (n=9), atrasentan-treated WT diabetic (n=9), atrasentan-treated TG diabetic (n=8) and the four corresponding nondiabetic groups (n=5). Atrasentan was administered orally via drinking water at 3 mg kg-1 per day over 28 days. All diabetic mice developed similar hyperglycaemia (27-30 mmol l-1). 3. Atrasentan treatment significantly improved left ventricular systolic and diastolic function in response to exogenous norepinephrine, but there were no differences between genotypes. 4. Atrasentan antagonized the diabetic impairments in endothelium-dependent coronary relaxation and thromboxane-receptor mediated aortic constriction. Further, it improved cardiac and renal oxidant status as evident from reduced tissue malondialdehyde levels. 5. Atrasentan reduced diabetic urine flow, proteinuria and plasma creatinine levels, but creatinine clearance was not significantly altered. 6. These results suggest that in experimental type 1 diabetes, blocking ETA receptors ameliorates myocardial, coronary and renal function and improves tissue oxidant status, whereas raising myocardial NO levels has neither beneficial nor deleterious effects on diabetic cardiomyopathy in this transgenic model.
Wölkart
Gerald
G
Department of Pharmacology and Toxicology, University of Graz, Universitätsplatz 2, Graz 8010, Austria.
Stessel
Heike
H
Saad
Zora
Z
Kirchengast
Michael
M
Brunner
Friedrich
F
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D000077868:Atrasentan; D002316:Cardiotonic Agents / Q000494:pharmacology; D003331:Coronary Vessels / Q000187:drug effects; D048909:Diabetes Complications / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000139:chemically induced / Q000235:genetics / Q000378:metabolism*; D065130:Endothelin A Receptor Antagonists; D005260:Female; D006321:Heart / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects / Q000235:genetics; D007668:Kidney / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008833:Microcirculation / Q000187:drug effects; D023421:Models, Animal; D032342:Muscle Cells / Q000187:drug effects / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism; D009569:Nitric Oxide / Q000494:pharmacology*; D052250:Nitric Oxide Synthase Type III / Q000235:genetics / Q000378:metabolism*; D009638:Norepinephrine / Q000494:pharmacology; D009928:Organ Specificity / Q000235:genetics; D011759:Pyrrolidines / Q000494:pharmacology*; D013311:Streptozocin
D000975:Antioxidants; D002316:Cardiotonic Agents; D065130:Endothelin A Receptor Antagonists; D011759:Pyrrolidines; D009569:Nitric Oxide; D013311:Streptozocin; D052250:Nitric Oxide Synthase Type III; D000109:Acetylcholine; D000077868:Atrasentan; D009638:Norepinephrine