Noninvasive motion vector analysis detected contractile changes in cardiomyocyte monolayers exposed to agents including 1-heptanol (2 mM), dl-sotalol (1 μM), and E-4031 (100 nM).
Motion vector analysis offers a sensitive, noninvasive approach for monitoring cardiomyocyte contractile behavior and screening drugs in vitro.
A noninvasive method for the characterization of cardiomyocyte contractile behavior is presented. Light microscopic video images of cardiomyocytes were captured with a high-speed camera, and motion vectors (which have a velocity dimension) were calculated with a high spatiotemporal resolution using a block-matching algorithm. This method could extract contraction and relaxation motions of cardiomyocytes separately and evaluate characteristics such as the beating rate, orientation of contraction, beating cooperativity/homogeneity in the monolayer, and wave propagation of impulses. Simultaneous phase-contrast imaging and calcium (Ca2+) fluorescence measurements confirmed that the timing of the maximum shortening velocity of cardiomyocytes correlated well with intracellular Ca2+ transients. Based on our analysis, gap junction inhibitors, 1-heptanol (2 mM) or 18-β-glycyrrhetinic acid (30 μM), resulted in clear changes in beating cooperativity and the propagation pattern of impulses in the cardiomyocyte monolayer. Additionally, the time dependence of the motion vector length indicated a prolonged relaxation process in the presence of potassium (K+) channel blockers, dl-sotalol (1 μM), E-4031 (100 nM), or terfenadine (100 nM), reflecting the prolonged QT (Q wave and T wave) interval of cardiomyocytes. Effects of autonomic agents (acetylcholine or epinephrine EPI) or EPI and propranolol on cardiomyocytes were clearly detected by the alterations of beating rate and the motion vector length in contraction and relaxation processes. This method was noninvasive and could sensitively evaluate the contractile behavior of cardiomyocytes; therefore, it may be used to study and/or monitor cardiomyocyte tissue during prolonged culture periods and in screens for drugs that may alter the contraction of cardiomyocytes.
Hayakawa et al. (Fri,) conducted a other in Cardiomyocyte contractile behavior. Motion vector analysis was evaluated on Contractile behavior characteristics (beating rate, orientation, cooperativity, wave propagation). Noninvasive motion vector analysis detected contractile changes in cardiomyocyte monolayers exposed to agents including 1-heptanol (2 mM), dl-sotalol (1 μM), and E-4031 (100 nM).