The role of perivascular adipose tissue in arterial function in health and disease

The majority of blood vessels are surrounded by adipocytes which have been labelled as perivascular adipose tissue (PVAT). It was originally assumed that this provided a structural support to the circulation, but in recent years it has been clear that these fat cells are highly metabolically active and produce a variety of adipokines and cytokines that can influence local vascular tone. The profile of these secreted factors is very much dependent upon the phenotype of the individual. The PVAT of healthy lean humans largely secretes vasodilator adipokines which will act in a paracrine fashion to reduce peripheral resistance and improve nutrient uptake into tissues, thereby ameliorating the risk of hypertension and diabetes. In obesity PVAT becomes enlarged and inflamed, and the bioavailability of vasodilator adipokines is reduced. The inevitable consequence is a rise in peripheral resistance with a higher blood pressure and a decrease in glucose uptake into tissues such as skeletal muscle leading to insulin resistance and the ultimate development of type 2 diabetes. This chapter will give a brief overview into what has been discovered in terms of PVAT in health and disease.