Perivascular Adipose Tissue Anticontractile Function Is Mediated by Both Endothelial and Neuronal Nitric Oxide Synthase Isoforms

Abstract

<b><i>Background:</i></b> The mechanism of the perivascular adipose tissue (PVAT) anticontractile effect is well characterized in rodent visceral vascular beds; however, little is known about the mechanism of PVAT anticontractile function in subcutaneous vessels. In addition, we have previously shown that PVAT anticontractile function is nitric oxide synthase (NOS) dependent but have not investigated the roles of NOS isoforms. <b><i>Objective:</i></b> Here, we examined PVAT anticontractile function in the mouse gracilis artery, a subcutaneous fat depot, in lean control and obese mice and investigated the mechanism in comparison to a visceral depot. <b><i>Method:</i></b> Using the wire myograph, we generated responses to noradrenaline and electrical field stimulation in the presence of pharmacological tools targeting components of the known PVAT anticontractile mechanism. In addition, we performed ex vivo “fat transplants” in the organ bath. <b><i>Results:</i></b> The mechanism of PVAT anticontractile function is similar between subcutaneous and visceral PVAT depots. Both endothelial and neuronal NOS isoforms mediated the PVAT anticontractile effect. Loss of PVAT anticontractile function in obesity is independent of impaired vasoreactivity, and function can be restored in visceral PVAT by NOS activation. <b><i>Conclusions:</i></b> Targeting NOS isoforms may be useful in restoring PVAT anticontractile function in obesity, ameliorating increased vascular tone, and disease.