To further clarify the potential role of IFN-γ in susceptibility to atrial fibrillation, the researchers performed optical mapping on rat hearts. Although IFN-γ perfusion did not significantly alter the atrial effective refractory period (AERP) or action potential duration (APD), it led to a reduction in conduction velocity. Furthermore, following IFN-γ perfusion, typical arrhythmic phenomena such as electrical alternans and calcium transient alternans were observed, along with an increased inducibility and prolonged duration of AF.

A. Schematic diagram of the optical mapping system used for analyzing the rat heart. The hearts were perfused with recombinant rat IFN-γ or a vehicle control in each panel. B. AERP 3 measurements in S1-S2 mode, with premature S2 stimuli ranging from 60 to 20 ms (n = 11 each). C. APD30 and APD80 maps and quantification, with S1S1 stimulation at 6 Hz (n = 11 each). D. Comparison of the conduction velocity, with S1S1 stimulation at 6 Hz (n = 11 each). E-F. The amplitude maps along with profiles tracing normal or the alternans of both action potentials and calcium transients at indicated sites, at a cycle length of 80 ms (n = 11 each). G. Recordings of action potential and pseudo-ECG after 50Hz pacing and phase maps showing normal or rotor signal. H-I. Comparison of the AF incidence and duration after 50Hz pacing (n = 11 each). Student’s t test in B and D. Two-way ANOVA in C. Fisher’s exact test in F. Wilcoxon rank-sum test in H and I. *, p < 0.05; **, p < 0.01. Scale bar (ms): 40 in E

Cardiovascular research ( IF 13.3）

DOI: 10.1093/cvr/cvae222