BugHeart: software for online monitoring and quantitation of contractile activity of the insect heart

Purpose The insect heart (dorsal vessel, DV) is considered a valuable model for studies on cardiac genetics, development, and physiology. However, as software for monitoring and quantitation of insect cardiac activity is not commercially available, most studies depend on time-consuming, post hoc analysis of video records. In this study, a computer program (BugHeart) was developed for this purpose, and applied to the determination of the octopamine effects on Tenebrio molitor DV. Methods The software was developed in Labview 11.0 for online processing of amplified video images of the transilluminated DV, in which systolic variation of the luminal diameter can be monitored over successive contraction cycles by video-tracking the tube inner edge. The possibility of adjustment of light intensity threshold and the introduction of calibration allow online quantitation of the DV luminal diameter and its cyclic variation (contraction amplitude), as well as heart rate (HR) estimation. The program can export video and text files for documentation and further analysis. Results BugHeart showed to be user-friendly and to allow continuous assessment of the preparation stability and response to drugs. Post hoc estimation of fractional vessel shortening (FS) and contraction temporal parameters was possible by applying simple calculations to the exported data. Octopamine produced significant cardioacceleration at 1 μM, while at 10 μM it also increased FS and abbreviated relaxation. Conclusions By providing online monitoring of cardiac activity and facilitating parameter estimation, BugHeart proved to be a useful tool and allowed characterization of octopamine cardiostimulatory effects in T. molitor —here reported for the first time.