TABLE 2

ASIC and ENaC properties

Data are from many different studies and reviews (Sutherland et al., 2001; Hesselager et al., 2004; Poirot et al., 2004; Blanchard and Kellenberger, 2011; Alijevic and Kellenberger, 2012; Wemmie et al., 2013). pH dependence and kinetics of ASICs vary between subtypes and also between orthologs of the same subtypes. Typical values are indicated here. For more information, see the relevant chapters.

	IC₅₀ Amiloride Inhibition^{^a}	Na⁺/K⁺ Permeability Ratio	pH₅₀ Activation	pHD₅₀ Steady-State Desensitization	Desensitization Time Constant (at pH Close to pH₅₀)	Most Important Sites of Expression
	μM				s
ASIC1a	10	6–13	6.2–6.6	∼7.2	∼0.4	CNS, PNS
ASIC1b	21	∼3	5.9–6.3	∼6.7	∼0.9	PNS
ASIC2a	28	∼10	4.0–4.9	∼5.6	∼1.4	CNS, PNS
ASIC3	60–100	∼12	6.4–6.7	∼7.1	∼0.3	PNS
ENaCαβγ	0.1	≥100	N.A.	N.A.	N.A.	Kidney, colon, lung

N.A., not applicable; pHD₅₀, pH of half-maximal desensitization.
↵^a For transient ASIC current component.