Figure 3. Initiation of ROV increases with contraction duration and branch order but is diminished with advanced age .

At 1 s post‐contraction, vasodilatation increased with branch order (FA<1A<2A<3A), and contraction duration (all at 100 Hz) whether expressed as absolute diameter change (μm, left panels) or relative responses (% max, right panels). These initial responses were attenuated for all branch orders in GM of old mice compared to young mice. ^Δ P < 0.05, main effect of branch order; ^# P < 0.05, main effect of age. ^* P < 0.05, old vs. young mice within respective branch order. Summary data are means ± SEM, n = 6 per age group.