Figure 7.

Role of short-term desensitization in spontaneous firing of the sinoatrial node. (A and E) Effects of 0.1 μM ACh on spontaneous firing in the Demir and Kurata sinoatrial node models. The current I_KACh model was incorporated into the Demir (A) and Kurata (E) sinoatrial node models (30–32) and 0.1 μM ACh was applied during the period indicated by the bar. The dashed lines indicate the zero level of each trace. The value of g_KACh was set at 1.1 (pS/pF) for the Demir model and at 6 (pS/pF) for the Kurata model. (B and F) Effects of 10 μM [ACh] on spontaneous firing. Parameters are the same as in A and E except that 10 μM ACh was applied. (C and G) Effects of 10 μM ACh on the K_ACh/high channel only. Parameters are the same as in B and F except that the K_ACh/low channel was replaced with the K_ACh/high channel. (D and H) Effects of 10 μM ACh on the K_ACh/low channel only. Parameters are the same as in B and F except that the K_ACh/high channel was replaced with the K_ACh/low channel.