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. 2016 Nov 15;7:542. doi: 10.3389/fphys.2016.00542

Figure 2.

Figure 2

Independent and reciprocal modulation of IK1 and INa in single cells and fibers. By standard convention, inward (depolarizing) stimulus currents are negative. (A). Changes in single cell threshold due to independent modulation of GNa. These results indicate that as GNa is increased, the magnitude of the threshold is lowered. GK1 was held at its default value of 0.5 μS. (B) Fiber threshold was also lowered as GNa was increased. GK1 was held at 0.5 μS and Ggj was held at 10 μS. (C) Fiber conduction velocity increased as GNa was increased (same conditions as B). (D) Changes in single cell threshold due to independent modulation of GK1: as GK1 is increased, the magnitude of the threshold is raised. GNa was held at 0.5 μS. (E) Fiber threshold was raised as GK1 was increased. For values of GK1 larger than 1.3 μS, the fiber was inexcitable. GNa was held at its default value of 0.5 μS and Ggj was held at 10 μS. (F) Fiber conduction velocity decreased as GK1 was increased (same conditions as D). (G) Changes in single cell threshold due to reciprocal modulation of GK1 and GNa. Cell threshold increased monotonically with the tandem changes in GK1:GNa. Three different ratios for GK1:GNa were used: 1:2, 1:1, and 2:1; the X-axis shows the GK1 values, the corresponding GNa value depends on the ratio used. (H) Fiber threshold changes due to reciprocal modulation of GK1 and GNa. Three different ratios for GK1:GNa were used (1:2, 1:1, and 2:1) while Ggj was held at 10 μS. The X-axis shows the GK1 values, the corresponding GNa value depends on the ratio used. (I) Fiber conduction velocity increased with reciprocal modulation of GK1 and GNa (same conditions as D). The X-axis shows the GK1 values, the corresponding GNa value depends on the ratio used.