Collateral density, remodeling, and VEGF-A expression differ widely between mouse strains. Physiol Genomics. 2007;30:179–191. doi

variability exists in collateral density and ischemia-induced collateral growth among species. To begin to probe the underlying mechanisms, which are unknown, we characterized two mouse strains with marked differences in both parameters. Immediately after femoral artery ligation, collateral and foot perfusion were lower in BALB/c than C57BL/6 (P 0.05 here and below), suggesting fewer pre-existing collaterals. This was confirmed with angiography and immunohisto-chemistry (35 % fewer collaterals in the BALB/c’s thigh). Recovery of hindlimb perfusion was attenuated in BALB/c, in association with 54 % less collateral remodeling, reduced angiogenesis, greater ische-mia, and more impaired hindlimb use. Densities of CD45 and CD4 leukocytes around collaterals increased similarly, but TNF- expres-sion was 50 % lower in BALB/c, which may contribute to reduced collateral remodeling. In normal tissues, compared with C57BL/6, BALB/c exhibit an altered arterial branching pattern and, like skeleta