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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, METHODS, RESULTS. Meshes: Adenosine Diphosphate, Animals, Arterioles, Diabetes Mellitus, Type 1, Endothelin A Receptor Antagonists, Male, N-Methylaspartate, Nitric Oxide Synthase, Nitric Oxide Synthase Type I, Nitric Oxide Synthase Type III, Peptides, Cyclic, Pia Mater, Rats, Rats, Sprague-Dawley, Receptor, Endothelin A, Vasodilation.
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Does inhibition of endothelin-1 receptors improve impaired nitric oxide synthase-dependent dilation of cerebral arterioles in type-1 diabetic rats? Context: Endothelin-1 has been implicated in the pathogenesis of many cardiovascular-related diseases, including diabetes. The goal of this study was to examine the influence of endothelin-1 receptors (ET(A)) in impaired responses of cerebral (pial) arterioles in type-1 diabetic rats. We measured responses of cerebral arterioles in non-diabetic rats to endothelial nitric oxide synthase (eNOS)-dependent (ADP), neuronal nitric oxide synthase (nNOS)-dependent (N-methyl-d-aspartic acid [NMDA]) and NOS-independent (nitroglycerin) agonists before and during application of BQ-123, an ET(A) receptor antagonist. In addition, we harvested brain tissue from non-diabetic and diabetic rats to measure the production of superoxide anion under basal conditions and during inhibition of ET(A) receptors. We found that diabetes specifically impaired eNOS- and nNOS-dependent reactivity of cerebral arterioles, but did not alter NOS-independent vasodilation. In addition, while BQ-123 did not alter responses in non-diabetic rats, BQ-123 restored impaired eNOS- and nNOS-dependent vasodilation in diabetic rats. Further, superoxide production was higher in brain tissue from diabetic rats compared with non-diabetic rats under basal conditions and BQ-123 decreased basal production of superoxide in diabetic rats.
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We suggest that activation of ET(A) receptors during type-1 diabetes mellitus plays an important role in impaired eNOS- and nNOS-dependent dilation of cerebral arterioles. Final Decision: yes