Potassium-Channel-Independent Relaxing Influence of Adipose Tissue on Mouse Carotid Artery

Since the cardiovascular consequences of obesity reportedly vary in different types of obesity, we investigated the influence of adipose tissue from different locales on the phenylephrine-induced tone of the mouse carotid artery. Vessels were mounted in a Mulvany-Halpern-type wire myograph, and adipose tissue, from the back (brown) or mesenteric or inguinal subcutaneous (white), was placed around the artery. Contractile responses to phenylephrine were not affected by brown adipose tissue but were reduced (p < 0.001) by either type of white adipose tissue, with no difference between the 2 locales. The relaxing effect persisted in the presence of the Kv7 channel inhibitor XE991 (10,10-bis(4-pyridinylmethyl)-9(10H)-anthracenone), the KATP channel inhibitor glibenclamide (1 µM), or the KV channel inhibitor 4-amino pyridine (1 mM), as well as after elevation of the extracellular potassium concentration to 30 mM. Contractions of rat carotid artery were equally reduced by mouse and rat subcutaneous adipose tissue. Thus, white, but not brown, adipose tissue reduces the adrenergic contractions of the carotid artery with no differences between the locales of origin, and the effect appears largely independent of potassium channels.