Effects of Some Inhibitors on the Temperature-Dependent Component of Resting Potential in Lobster Axon

The resting membrane potential of the lobster axon becomes 5–8 mv more negative when the temperature of the perfusion solution is increased 10°C. This potential change is about twice that predicted if the axon membrane potential followed that expected for a potassium ion electrode potential. When the inhibitors, 2, 4-dinitrophenol, sodium cyanide, and sodium azide, were added separately to the perfusion medium the potential change was reduced to about 1.4 times that predicted for a potassium ion electrode potential. Assays of axons exposed to these inhibitors showed that ATP levels were reduced to about one-fourth that obtained for control axons. Ouabain added to the perfusion medium reduced the potential change to that expected for a potassium ion electrode potential. These results suggest that the resting potential changes with temperature as a result of the activity of an electrogenic ion pump.