Figure 3.

Temperature sensitivity of the M-ihhibition. (a) In the absence of prepuff, MCh or ACh could inhibit nAChRs current only at 36°C but not 22°C. Left panels, Nic (1 mM), ACh (1 mM) and MCh (1 mM) + Nic (1 mM) induced currents at 22°C and 36°C, respectively. Right panel, the statistics of the experiments using protocol of left panel. Without prepuff at 36°C, the inhibition of nAChRs current was 33 ± 3% by 1 mM ACh (n = 5), and 34 ± 4% (n = 6) by 1 mM MCh. Note, there was no inhibition of nAChRs by MCh or ACh at 22°C. (b) The MiI of nAChRs was strongly dependent on temperature and prepuff time. Left two panels show currents induced by 100 µM-Nic at 22°C (neuron 1) and 36°C (neuron 2), respectively. MCh (1 mM) was prepuffed with MCh-prepuff-solution. MCh (1 mM) was also included in the Nic (100 µM)-puffing solution for the traces marked with the prepuff times (0 s, 0.5 s, etc.), except where only ‘Nic’ and ‘wash’ are marked. Right panel shows the statistics. The time constants of MiI versus prepuff time were 1.32 s, 0.58 s and 0.27 s, corresponding to 22°C (n = 11), 30°C (n = 8) and 36°C (n = 8), respectively.