ANGIOGENESIS BUT NOT COLLATERAL GROWTH IS ASSOCIATED WITH ISCHEMIA AFTER FEMORAL-ARTERY OCCLUSION

It remains unclear whether capillary sprouting (angiogenesis) and in s itu growth of muscular collateral arteries share the same or different molecular mechanisms. To study the role of ischemia in these two form s of vascular proliferation, we measured tissue flows and maximum coll ateral conductances in hindlimbs of 22 rabbits previously subjected to either acute, 7-day, 21-day, or no femoral artery occlusion. After 1 wk of femoral artery occlusion, corkscrew collaterals were observed ra diographically in the thigh. These collaterals showed histochemical ev idence for active proliferation of endothelial and smooth muscle cells . Maximum collateral conductance increased sixfold in the Ist wk. Perf usion deficits, however were only observed in the distal adductor musc les (region of collateral reentry). In the lower leg, which suffered f rom a profound perfusion deficit, conductance increased in the absence of any visible collateral arteries but with evidence for capillary pr oliferation. This study therefore demonstrates that upon femoral arter y occlusion angiogenesis occurs in regions of profound ischemia, where as no direct correlation can be drawn between ischemia and collateral artery development.