The effects of ouabain on resting membrane potential and hyperpolarization-activated current in neonatal rat nodose ganglion neurons

To determine whether the responses of resting membrane potential (RMP) and hyperpolarization-activated current (IH) are altered by the application of ouabain, one of the Na+-K+ pump inhibitors, in neonatal rat small-diameter (<30microm) nodose ganglion (NG) neurons, we examined the effects of 1microM ouabain on those responses using perforated patch-clamp techniques. In current-clamp mode, the RMP was 40.2+/-1.6mV (n=31). Twenty of 31 cells tested were depolarized by ouabain application, and these responses were associated with an increase in the cell input resistance. In the remaining 11 cells studied, 3 showed hyperpolarization in response to ouabain and 8 showed no effect on RMP. In voltage-clamp mode, 1muM ouabain application enhanced the IH in all of 10 neurons examined. These results suggest that ouabain application at 1microM is capable of setting both the RMP level and the neuronal excitability in small-diameter NG neurons.