Figure 9

Change in extracellular Ca²⁺concentration shifts the reversal potential of HyNaCs. A) Xenopus oocytes expressing HyNaC2/3/7 were activated by 100 nM Hydra-RFamide I, corresponding to its EC₅₀. The conductive cation in the extracellular solution was either 1 mM Ca²⁺, or 10 mM Ca²⁺, or 140 mM Na⁺. Reversal potentials were determined by voltage ramps from -100 mV to +30 mV in two seconds. Background currents had been subtracted by voltage ramps in the absence of agonist. B) Diagram showing the shift of the reversal potentials for different HyNaC combinations, when the extracellular solution contained 1 or 10 mM Ca²⁺ as the only conductive ion. HyNaCs had been activated by a concentration of Hydra-RFamide I that corresponds to the individual EC₅₀. HyNaCs, Hydra Na⁺ channels.