TRPV4 and atrial fibrillation: In order to investigate the potential role of the TRPV4 ion channel in the increased expression of IL6, IL8, COX2 and MMP1 induced by hyperphysiological stretching, we selected the stretching duration of 1 h, and further cyclically stretched AF cells in the absence or presence of the selective TRPV4 antagonist GSK2193874 (20 to 500 nM).