Abstract 18569: Deletion of AT2 Receptor Prevents SHP-1 Expression and Improves Blood Flow in Diabetic Ischemic Hindlimb

Abstract

Introduction: Ischemia due to narrowing of femoral artery and distal vessels is also a major cause of peripheral arterial disease and morbidity affecting patients with diabetes. We have previously reported that the inhibition of the angiogenic response to PDGF and VEGF in diabetic mice (DM) is associated with the increase expression of SHP-1, a protein that can be activated by the AT2 receptors. It has been shown that the deletion of AT2 receptor in mice promotes angiogenesis within the ischemic muscle, but its role in diabetic condition remains unknown. Hypothesis: Our hypothesis is that AT2 receptor induced SHP-1 which contributed to inhibition of pro-angiogenic factor actions in DM mice during ischemia. Methods: Non-DM and DM AT2 null mice underwent femoral artery ligation after two months of diabetes. Blood perfusion was measured every week up to 4 weeks post-surgery. Expression of AT1, AT2, angiotensin-converting enzymes (ACE1/2), SHP-1 and angiogenic factors was evaluated. Results: Blood flow in the ischemic muscle of DM-AT2KO mice recovered faster and up to 80% four weeks following the surgery, compared to a 51% recovery in DM mice. After four weeks, the expression of pro-angiogenic factors (HIF-1α and VEGF) was diminished in the DM and remained at a basal state in the DM-AT2KO suggesting a faster recovery process in these mice. Interestingly, two weeks after ligation, the expression of VEGF and HIF-1α are elevated in DM-AT2DM compared to DM mice and correlated with a reduction of SHP-1 expression in the ischemic muscles. Conclusion: Our results suggest that the deletion of AT2 receptor prevented SHP-1 expression induced by diabetes and restored pro-angiogenic factors causing blood flow reperfusion following ischemia.