Fig. 4. Synaptic responses elicited by the opener inhibitor (OI) and the common inhibitor (CI) reverse polarity at similar temperatures. The amplitudes of inhibitory junction potentials (IJPs) elicited by stimulation of OI and CI are plotted as a function of temperature. All measurements were made in a single muscle fiber; insets show synaptic responses at 2°C and 18°C. Note that IJPs are hyperpolarizing at colder temperatures (<10°C) and depolarizing at warm temperatures (>12°C). Scale bars, 0.5 mV, 0.2 s.