Altered role of smooth muscle endothelin receptors in coronary endothelin-1 and alpha1-adrenoceptor-mediated vasoconstriction in Type 2 diabetes.
Regulation of vascular tone and blood flow involves interactions between numerous local and systemic vascular control signals, many of which are altered by Type 2 diabetes (T2D). Vascular responses to endothelin-1 (ET-1) are mediated by endothelin type A (ET(A)) and type B (ET(B)) receptors that have been implicated in cross talk with alpha(1)-adrenoceptors (alpha(1)-AR). ET(A) and ET(B) receptor expression and plasma ET-1 levels are elevated in T2D; however, whether this influences coronary alpha(1)-AR function has not been examined. Therefore, we examined the effect of ET(A) and ET(B) receptor inhibition on coronary vasoconstriction to ET-1 and alpha(1)-AR activation in a mouse model of T2D. Coronary vascular responses were examined in isolated mouse hearts from control and diet-induced T2D C57BL/6J mice. Responses to ET-1 and the selective alpha(1)-AR agonist phenylephrine (PE) were examined alone and in the presence of the nitric oxide synthase inhibitor N(omega)-nitro-l-arginine methyl ester (l-NAME) alone or in combination with selective ET(A) or ET(B) receptor inhibitors BQ-123 and BQ-788, respectively. Vasoconstriction to ET-1 was enhanced, whereas ET(B), but not ET(A), receptor blockade reduced basal coronary tone in T2D hearts. In the presence of l-NAME, ET(A) receptor inhibition attenuated ET-1 vasoconstriction in both groups, whereas ET(B) inhibition abolished this response only in control hearts. In addition, ET(A) inhibition enhanced alpha(1)-AR-mediated vasoconstriction in T2D, but not control, hearts following l-NAME treatment. Therefore, in this model, enhanced coronary ET-1 responsiveness is mediated primarily through smooth muscle ET(B) receptors, whereas the interaction with alpha(1)-ARs is mediated solely through the ET(A) receptor subtype.
Department of Biomedical Sciences, Ohio University College of Osteopathic Medicine, Athens, Ohio 45701, USA.
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D058646:Adrenergic alpha-1 Receptor Agonists; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D003331:Coronary Vessels / Q000378:metabolism / Q000503:physiopathology; D003921:Diabetes Mellitus, Experimental / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology*; D003924:Diabetes Mellitus, Type 2 / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology*; D004040:Dietary Carbohydrates / Q000009:adverse effects; D004041:Dietary Fats / Q000009:adverse effects; D004305:Dose-Response Relationship, Drug; D065130:Endothelin A Receptor Antagonists; D065131:Endothelin B Receptor Antagonists; D019332:Endothelin-1 / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D009765:Obesity / Q000150:complications / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology; D009842:Oligopeptides / Q000494:pharmacology; D010456:Peptides, Cyclic / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D044022:Receptor, Endothelin A / Q000378:metabolism*; D044023:Receptor, Endothelin B / Q000378:metabolism*; D018340:Receptors, Adrenergic, alpha-1 / Q000378:metabolism*; D014661:Vasoconstriction / Q000187:drug effects
D058646:Adrenergic alpha-1 Receptor Agonists; D000316:Adrenergic alpha-Agonists; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D065130:Endothelin A Receptor Antagonists; D065131:Endothelin B Receptor Antagonists; D019332:Endothelin-1; D004791:Enzyme Inhibitors; D009842:Oligopeptides; D010456:Peptides, Cyclic; D010880:Piperidines; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; D018340:Receptors, Adrenergic, alpha-1; D010656:Phenylephrine; D009569:Nitric Oxide; C086539:BQ 788; D019001:Nitric Oxide Synthase; C072247:cyclo(Trp-Asp-Pro-Val-Leu); D019331:NG-Nitroarginine Methyl Ester