Fig. 2.

Peak hyperemic (ΔFBF) and vasodilator (ΔFVC) responses to single forearm contractions at 10% (A), 20% (B), and 40% (C) MVC across conditions (control, LBNP, and phentolamine). Under control conditions, peak hyperemic vasodilator responses were similar in young and older adults at 10% MVC. However, peak responses were attenuated in older adults at 20% and 40% MVC. Sympathetic stimulation (via LBNP) blunted peak hyperemic and vasodilator responses at all contraction intensities in young adults only. Conversely, α-adrenergic blockade (via phentolamine) augmented peak responses at all contraction intensities in older adults only. *P < 0.05 vs. young adults; †P < 0.01 vs. control.