bFGF increases collateral blood flow in aged rats with femoral artery ligation

We tested the hypothesis that aged animals are as responsive as the young adult animals in expanding collateral vasculature under a similar treatment of basic fibroblast growth factor (bFGF). Two age groups of male Fischer 344 rats (11 mo old; n = 32, 23 mo old; n = 43) weighing similar to 385 g were subdivided into normal, acute ligation [femoral artery (FA) ligated 3 days before blood flow (BF) measurement] or ligated groups for 16 days and received recombinant human bFGF intra-arterial infusion at doses of 0, 0.5, 5, and 50 mu g . kg(-1) . day(-1). BF was determined with Sr-85- and Ce-141-labeled microspheres during treadmill running at 15 and 20 m/min at 15% grade. Blood presure (BP) values were similar to 149 and similar to 163 mmHg (p < 0.05); heart rates were similar to 496 and similar to 512 beats/min in the aged and young adult groups during running, respectively. Maximal collateral BF values were confirmed by no additional BF increase in the calf muscle at the higher speed. Ligation of the FA for 3 days reduced the BF reserve to the calf muscle by similar to 90%. Calf muscle BF was modestly greater (10 ml . min(-1) . 100 g(-1)) by 16 days in the carrier group. bFGF infusion expanded collateral BF in a dose-dependent manner with an increase of 33 and 42 ml . min(-1) . 100 g(-1) (P < 0.001) in the 5 and 50 mu g . kg(-1) . day(-1) bFGF groups, respectively. Aged animals showed similar BF improvements as observed with the adult groups in response to ligation surgery and bFGF treatment. Our data indicate that the aged rats (similar to 23 mo old) remain responsive to exogenous bFGF induced in developing collateral-dependent BF as the young adult (similar to 11 mo old) controls. This suggests that the influence of bFGF in expanding collateral BF should not be preempted in the aged group, the population most affected by peripheral arterial insufficiency.