The role of the electrogenic sodium pump in modulation of pacemaker discharge of Aplysia neurons

The discharge of Aplysia pacemaker neurons varies with temperature over the range 10 to 22°C. Three types of frequency‐temperature plots are found, with maximal discharge at lowest, intermediate or highest temperatures. In the presence of ouabain, however, all cells show maximal discharge at the highest temperature, suggesting that the steady state activity of an electrogenic sodium pump is an important determinant of membrane excitability. The average magnitude of pump current, as indicated by the applied current necessary to restore discharge to control values after ouabain application, was about 4 namps at 20°C but near zero at 10°C. These neurons may be excellent models of mammalian thermoreceotprs.