The comprehensive analysis of DEG/ENaC subunits in Hydrareveals a large variety of peptide-gated channels, potentially involved in neuromuscular transmission

Table 1 Summary of the biophysical properties of putatively physiological HyNaCs

HyNaC	EC₅₀RFa I [μM]	Hill Coeff.	I_maxRFa I [μA]	E_Rev[mV]	P_Ca/P_Na	IC₅₀Dimi [μM]	I_Amil/I
2/3/5	3.48 ± 0.55 (9)	1.2 ± 0.1	9.2 ± 1.9 (9)	16 ± 2 (9)	3.4	0.45 ± 0.09 (10)	0.5 ± 0.1 (10)
2/11/5	13.8 ± 1.9 (12)	0.9 ± 0.1	2.7 ± 0.3 (12)	17 ± 1 (8)	3.3	31.4 ± 9.4 (8)	0.7 ± 0.1 (8)
2/3/6	0.29 ± 0.06 (10)	1.2 ± 0.2	15.7 ± 3.2 (10)	9 ± 2 (8)	3.7	0.09 ± 0.02 (9)	0.3 ± 0.1 (9)
2/4/6	0.70 ± 0.08 (12)	1.3 ± 0.1	8.8 ± 1.5 (12)	14 ± 3 (9)	2.7	0.05 ± 0.02 (9)	0.3 ± 0.1 (9)
2/3/7	0.19 ± 0.04 (14)	1.6 ± 0.4	19.6 ± 1.8 (14)	12 ± 1 (8)	2.8	0.16 ± 0.08 (7)	0.3 ± 0.1 (7)
2/9/7	0.04 ± 0.01 (9)	1.5 ± 0.3	7.4 ± 0.9 (11)	7 ± 1 (10)	2.9	1.70 ± 0.58 (9)	0.3 ± 0.1 (9)
2/10/7	>30 (12)	n.d.	11.9 ± 1.5 (12)	n.d.	n.d.	5.40 ± 1.45 (6)	0.8 ± 0.1 (6)

Properties are summarized for HyNaCs with a putative physiological role as judged by functionality in oocytes and by co-expression as revealed by ISH. EC₅₀ RFa I, concentration of Hydra-RFamide I at which half-maximal activation was achieved; I_max RFa I, current amplitude at maximal concentration of Hydra-RFamide I; E_Rev, reversal potential of RFamide I-activated currents with standard bath; P_Ca/P_Na relative permeability of Ca²⁺ to Na⁺; IC₅₀ Dimi, concentration of diminazene at which half-maximal inhibition was achieved; I_Amil/I, relative current remaining after block by 100 μM amiloride. Values indicate mean ± standard error; the number n of individual oocytes is indicated in brackets. HyNaC, Hydra Na⁺ channel; ISH, in situ hybridization.

ISSN: 1741-7007