Abstract 232: The P2Y2 Nucleotide Receptor Mediates Blood Flow Recovery Following Hindlimb Ischemia in Mice

Abstract

Objectives: Arteriogenesis is a process by which small resistance vessels mature into large caliber collateral arteries in response to arterial occlusive disease. The forces stimulating arteriogenesis nclude shear stress and circumferential wall stress. Nucleotides are released from cells in response to mechanical stimuli and may activate nucleotide receptors. Thus, we hypothesize that the P2Y 2 nucleotide receptor, expressed by vascular cells, mediates arteriogenesis. Methods: C57Bl6 NJ (WT) and P2Y 2 R KO mice (n=8/group) underwent unilateral femoral artery ligation (FAL). Perfusion was measured immediately after ligation and at 3, 7, 14, 21, and 28 days using laser Doppler perfusion imaging (LDPI). Mice were sacrificed at 28 days and tibialis anterior collected for histology. Results: LDPI of the ischemic hindlimb showed a return to baseline perfusion in WT mice (Figure). P2Y 2 KO mice recovered to <40% of baseline. Additionally, 4/8 P2Y 2 KO mice developed wounds of the ischemic limbs vs. 0/8 of WT mice. Histological analysis of tibialis anterior demonstrated regenerating myocytes in 3/4 P2Y 2 KO vs. 1/4 WT animals. By immunohistochemistry, angiogenesis was significantly increased in P2Y 2 KO with a CD31+cell/myocyte ratio of 1.974 vs. 1.314 of WT (p=0.05). There was also greater inflammation in P2Y 2 KO with CD45+ cell infiltration over 3-fold that of WT (p<0.001). Conclusion: The P2Y 2 nucleotide receptor is important for blood flow recovery in a murine model of FAL. P2Y 2 KO mice also demonstrated delayed muscle regeneration with greater angiogenesis and inflammation in ischemic limbs. Further molecular analyses are needed to elucidate the mechanisms involved.