Figure 4

MEF-induced cardiac pacing in an in vivo rat model.

(a) Bradycardia was induced by xylazine and IMPs were injected into the tail vein. First, the IMPs were captured in the RV by the electromagnet operating on DC mode. Then, magnetic pulses were applied in order to mechanically stimulate the heart. The blue line indicates the arterial pressure (AP) and the red line indicates the current through the electromagnet coil, which correlates with the magnetic induction generated by the electromagnet. Plus (+) signs indicate heart beats that are synchronized with the magnetic pulses (see more detailed information of the pacing in A in Fig. 3 in supplementary information). To examine the fading of pacing, similar experiments were repeated, but rats were sacrificed before (b) or after (c) the magnetic pulses were applied. Thereafter, animals were frozen and the hearts were cryo-sectioned to visualize the content of the RV. The IMP sediments are marked with blue arrows. High magnification (squares) clearly shows that the red substance in the ventricle of c is blood and it is clear that the amount of IMPs in b is much larger than that in (c) Scale bar is 1 mm.