NTRK1 and atrial fibrillation: The percentages of TrkA-positive NP and AF cells in the gel group were significantly higher than those in the control group at each time point, except for the percentages of AF cells on day 4 and 28 (control vs. gel, P < 0.01, each time point except for the percentages of AF cells on day 4 and 28, Fig. 4g,h).