New perspectives on vascular wall signaling: role of perivascular adipocytes and fibroblasts.

This communication represents personal perspectives of recent development in the newly evolved areas in vascular signaling mechanisms at the anatomical level of vascular walls from outside in, that is, from perivascular adventitial side to effectuate the control of vascular reactivity. Since half a century ago, the focus of interest in vascular biology has been confined primarily to the study of the excitation-contraction coupling of vascular smooth muscle (VSM) as well as neuroeffector mechanisms. During the past 3 decades, considerable advancement in the understanding of vascular signaling has been made via the discovery of endothelium-derived relaxation factors (EDRF), endothelium-derived hyperpolarizing factors (EDHF) and endothelium-derived contracting factors (EDCF). The discovery of nitric oxide (NO) as a major cellular messenger has also helped open up another huge area of research in oxidative stress and vascular diseases. In the past decade, concepts on vascular wall signaling have been extended from vascular endothelial cells and then translated to the other seemingly inert cellular components, such as perivascular adipocytes and adventitial fibroblasts. Growing body of evidences show that these cellularities contribute to both functional as well as structural integrity in vasculature with significant pathophysiological implications.