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Updated: Jul 20, 2026

Assessment of Vascular Tone Responsiveness using Isolated Mesenteric Arteries with a Focus on Modulation by Perivascular Adipose Tissues
Published on: June 3, 2019
Effect of age on vascular beta2-adrenergic receptor desensitization is not mediated by the receptor coupling to
William E Schutzer1, Hong Xue, John F Reed
1Portland VA Medical Center, Research Service, Portland, OR 97201, USA.
Abstract:
Beta-adrenergic receptor (beta-AR)-mediated vasorelaxation declines with age. In the vasculature, beta2-AR undergoes protein kinase A-mediated desensitization that causes a switch in the G protein coupled to beta2-AR; Galphai links instead of Galphas. We exposed Fischer 344 rat aortae of increasing age to a desensitizing dose of isoproterenol, and determined its effect on beta2-AR-mediated vasorelaxation. Desensitization decreased beta2-AR-mediated vasorelaxation in young aortae only. Subsequently, we used pertussis toxin to block Galphai to determine whether changes in beta2-AR/G protein coupling occurred. Galphai inhibition did not reverse desensitization or the age-related change, but there appears to be a population of beta2-AR linked to Galphai, as pertussis toxin treatment improved beta2-AR-mediated vasorelaxation in aortae from animals of all ages. These findings suggest aortic beta2-AR in older animals may be maximally desensitized, which would explain impaired vasorelaxation. Our results also imply that protein kinase A-mediated beta2-AR desensitization may not be responsible for the age-related decline.
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