Figure 3.

Peptide-activated currents in the absence of Na⁺_e. (A; left) Representative current trace for HyNaC2/3/5 in solutions containing 1 mM Ca²⁺ together with 140 mM of either NMDG⁺ or Na⁺. 1 µM RFamide I was used for activation. (Right) Control experiment in NMDG⁺ solution nominally free of Ca²⁺. Similar results were observed in four out of four oocytes. (B; left) Representative current trace for HyNaC2/3/5 in solutions containing 10 mM Ca²⁺, 10 mM Ca²⁺ and 10 mM Na⁺, or 10 mM Na⁺ (nominally free of Ca²⁺). Solutions additionally contained 10 mM HEPES, pH 7.4, and NMDG⁺ at concentrations to reach similar osmolarity (10 Ca²⁺: 125 mM NMDGCl; 10 Ca²⁺/10 Na⁺: 115 mM NMDGCl; and 10 Na⁺: 130 mM NMDGCl). Oocytes had been injected with EGTA; 2 µM RFamide I was used for activation. Holding potential was −85 mV. (Right) Quantitative comparison of current amplitudes. ***, P < 0.001.