Figure 2. Forearm vasodilatory responses to ATP and adenosine infusion.

Vasodilatation to P₁-receptor agonist adenosine infusion was not significantly impaired in older adults (A). Aminophylline significantly reduced vasodilatation to adenosine at all drug doses in both young and older adults. No significant age-related impairment in vasodilatation to the purinergic receptor agonist ATP was observed and this vasodilatation was unaffected during aminophylline infusion regardless of age (B). †P < 0.05 vs. without aminophylline.