Uk14304

Protocol 1: regional activation of α1R, α2R, Y1R and P2X1R
Five groups of animals were used to evaluate arteriolar responses to phenylephrine (PE; α1R specific agonist; Sigma-Aldrich, St Louis, MO, USA), UK 14304 (α2R specific agonist; Tocris Biosciences, St Louis, MO, USA), neuropeptide Y (NPY; Tocris Biosciences) and ATP (Sigma-Aldrich). ATP has been shown to exhibit both vasoconstrictor (via P2X1R activation; Hopwood & Burnstock, 1987) and vasodilatator (Hellsten et al. 1998) effects; therefore, in an attempt to isolate ATP-mediated vasoconstriction (Buckwalter et al. 2004) , we conducted a separate set of experiments with a fifth group of animals receiving α,β-methylene ATP (αβ-meATP; potent P2X1 receptor agonist; Sigma-Aldrich), a stable non-degradable ATP analogue. All experiments were conducted in the rat GM arteriolar network, with one agonist evaluated per animal. Arteriolar responses were recorded at log increments (PE: 10 -9 to 10 -4 m; UK 14304: 10 -9 to 10 -5 m; NPY: 10 -13 to 10 -8 m; ATP: 10 -9 to 10 -4 m; αβ-meATP: 10 -9 to 10 -5 m) and were evaluated when the diameter responses stabilized and remained static for a minimum of 5-10 min.