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. 2018 Apr 9;8(10):2752–2764. doi: 10.7150/thno.22599

Figure 4.

Figure 4

Injection of polypyrrole-chitosan improves conduction velocity across scar tissue. Rat hearts were subjected to cryoinjury (injured region marked by dashed yellow lines). Seven days later, injured rat hearts were injected with saline, chitosan (CHI), or polypyrrole:chitosan (PPY:CHI). Rats were sacrificed 28 days later and electrical signal conduction kinetics of the ex vivo Langendorff-perfused rat hearts were measured by perfusing rat hearts with the voltage-sensitive dye di-4-ANEPPS. (A) Optical mapping of electrical impulse propagation (black arrows) through the left ventricle (LV) of the heart was performed. The start point is marked with a star. (B) Electrical impulse propagation wave velocity was calculated as the distance travelled up the LV (white dashed arrows)/time elapsed. Velocity was significantly decreased post-cryoinjury, and injection of saline or CHI did not affect this velocity. However, PPY:CHI-treated hearts exhibited conduction velocities that were similar to uninjured hearts, and significantly greater than saline- or CHI-injected cryoinjured hearts (n = 3 for healthy control, n = 4 for saline, n = 4 for CHI, and n = 5 for PPY:CHI; * p < 0.05). Data are shown as mean ± SEM. Representative recordings are provided as Movie S7 (healthy), Movie S8 (saline), Movie S9 (CHI), and Movie S10 (PPY:CHI).