Role of β 3 ‐Adrenergic Receptors in Rat Aortic Endothelial Cell Function

Abstract

Long-term success of percutaneous trans-luminal coronary angioplasty (PTCA) is limited by the frequent occurrence of restenosis, resulted from vascular smooth muscle cell (VSMC) proliferation and migration due to the procedure-induced endothelial damage. Speeding the healing of the endothelial layer has been considered as one of the major approaches to reduce the risk of restenosis. Basic fibroblast growth factor (bFGF), a major growth factor released after injury, regulates endothelial cell proliferation and migration and promotes endothelial layer healing. Our previous results revealed that β3-adrenergic receptor (β3-ARs) expression is upregulated in newly formed intima in injured blood vessels and activation of β3-ARs enhanced bFGF-induced VSMC proliferation and migration. However, the role of β3-ARs in endothelial function, specifically in injured arteries, is uncertain. The purpose of this study is to determine if activation of endothelial cell β3-ARs potentiates bFGF-induced endothelial cell proliferation and/or migration by using rat aortic endothelial cells. Cell proliferation was determined by measuring viable cell numbers using Resazurin. Cell migration will be quantified by a monolayer wound healing assay in the presence of a cell proliferation inhibitor, hydroxyurea. A dose-dependent inhibition of cell proliferation was performed to optimize the concentration of hydroxyurea in cell migration experiments. Our results revealed that pretreatment of endothelial cells with a selective β3-AR agonist, CL316,243, enhanced bFGF-induced vascular endothelial cell proliferation. We also found that 5μM of hydroxyurea completely inhibited cell proliferation induced by growth factors. In conclusion, our data suggest that activation of β3-ARs may speed the healing of endothelial layer by promoting cell proliferation and that including 5μM of hydroxyurea in cell migration experiments will allow us to measure the cell motility accurately and ensure that proliferation does not take place.