Fig. 5. Effects of various α adrenoceptor agonists and β adrenoceptor agonist on Aδ-fiber and C-fiber excitatory postsynaptic currents (EPSCs) in substantia gelatinosa neurons. (A and B ) Relative peak amplitudes of Aδ-fiber EPSC (A ) and C-fiber EPSC (B ) in the presence of an α1agonist, phenylephrine (10 μm; α1), an α2agonist, clonidine (10 μm; α2), an α2Aagonist, oxymetazoline (10 μm; α2A), or a β agonist, isoproterenol (40 μm; β) to that in the control (Ctl). Note that the α2and α2Abut not α1and β agonists significantly inhibited both EPSCs. The number of neurons examined is shown in parentheses; *P < 0.01.