Table 3.

Comparison of IC₅₀ values in inhibiting frog or rat sciatic nerve fast-conducting CAPs and TTX-sensitive or -resistant Na⁺ channels among adrenoceptor agonists.

Adrenoceptor Agonists		Frog CAP IC50 (mM)	Rat CAP IC50 (mM)	TTX-Sensit. Na+ Channel Current IC50 (mM)	TTX-Resist. Na+ Channel Current IC50 (mM)	References
	Adrenaline	n.d. (no effect, 1 mM)				[22]
	Noradrenaline	n.d. (no effect, 1 mM)				[22]
α2 Agonist	Dexmedetomidine	0.40		ca. 20% reduct. (0.01 mM)	0.058	[22,148,156]
	Oxymetazoline	1.5				[22]
	Clonidine	ca. 20% reduct. (2 mM)	2.0	0.824	0.26	[22,143,148,155]
α1 Agonist	Phenylephrine	n.d. (no effect, 1 mM)				[22]
β Agonist	Isoproterenol	n.d. (no effect, 1 mM)				[22]

Here, when IC₅₀ values are not available, it is partly shown for comparison how the CAPs and channels are affected by drugs. sensit.: sensitive; resist.: resistant; reduct.: reduction (where % value indicates the extent of the reduction at the concentration shown in parentheses); n.d.: not determined.