Figure 4.

Endothelial-specific Tnf ablation does not protect against atrial arrhythmia inducibility in swim-trained mice. Atrial arrhythmia inducibility was determined using intracardiac octopolar catheters inserted into the right atria via the superior jugular vein. (A) Representative electrical recordings during and following programmed electrical stimulations in sedentary (n = 14 per group) and swim-exercised (n = 18 and 24, respectively, per group) mice with (Tie2-Cre+) and without (Cre−) endothelial cell-specific Tnf ablation. Prolonged highly disorganized electrical patterns lasting greater than 10 s, indicative of atrial arrhythmias, were seen in swim-exercised Tie2-Cre+ and Cre− mice. (B and C) Endothelial cell-specific Tnf ablation did not decrease (P value from 2 × 2 contingency table using Fisher’s exact test) the incidence atrial arrhythmias lasting >10 s or decrease the duration of arrhythmia episodes. Data presented as mean ± S.e.m. n values listed within each individual panel. P values for arrhythmia durations from Mann–Whitney U test with Dunn’s multiple comparisons test. *P < 0.05; **P < 0.01.