Figure 2. Forearm blood flow at rest, during each hyperaemic condition and during infusion of α-agonists.

Steady-state hyperaemia was similar during rhythmic handgrip exercise, adenosine and ATP infusions for trials involving the α₁-agonist phenylephrine (A; Pre-PE) and the α₂-agonist dexmedetomidine (B; Pre-Dex). Forearm blood flow was reduced significantly with both α-agonists during adenosine and exercise, but the response was attenuated during exercise. In contrast, α-agonist infusion did not significantly reduce forearm blood flow during ATP. *P< 0.05 vs. steady state (Pre-vasoconstrictor; PE/Dex) within condition; †P< 0.05 vs. adenosine during α-agonist infusion.