Perivascular adipose tissue modulates vascular function in the human internal thoracic artery

Area of Science:

• Cardiovascular Biology
• Vascular Physiology
• Adipose Tissue Research

Background:

• Perivascular adipose tissue (PVAT) surrounding blood vessels plays a role in vascular function.
• Studies in rats suggest aortic PVAT secretes a vasodilator substance.
• The presence and function of such a vasodilator in human arteries remain to be fully elucidated.

Purpose of the Study:

• To investigate if human internal thoracic arteries (ITAs) possess a vasodilator secreted by PVAT.
• To characterize the mechanism of action of this potential vasodilator.

Main Methods:

• Human ITAs with and without PVAT were studied using wire myography.
• Vascular responses to constricting agents were assessed.
• Incubation solutions from PVAT-intact and PVAT-denuded arteries were transferred to assess vasodilator activity.
• Pharmacological blockade of specific ion channels was employed to elucidate the mechanism.

Main Results:

• PVAT significantly attenuated contractions induced by U 46619 and phenylephrine.
• Transfer of incubation solution from PVAT-intact arteries induced significant relaxation in recipient arteries.
• This relaxation was mediated by the activation of calcium-dependent potassium channels.
• The effect was independent of endothelial function and specific to certain contractile stimuli.

Conclusions:

• Human ITA PVAT releases a transferable relaxation factor.
• This factor activates calcium-dependent potassium channels, leading to vasodilation.
• Retaining PVAT during coronary artery bypass grafting may help prevent graft vasospasm.