Development in Cell Manipulation Techniques for the Study of Single Cardiomyocyte Mechanics
The externally homogeneous mechanical activity of the heart results from the integration of the heterogeneous activity of the cardiomyocytes. Therefore, in order to understand the integrated mechanical function of the heart, it is important to study the regional single cell mechanics. Cardiac left ventricular pressure-volume relationship has been commonly used to evaluate the cardiac performance. In physiological contractions, pressure-volume relation curve for one beat forms a rectangular work-loop that is divided into four phases: isovolumic contraction, ejection, isovolumic relaxation, and filling phase. For single cardiomyocytes that constitute the heart, these phases correspond to isometric contraction, quasi-isotonic contraction, isometric relaxation, and quasi-isotonic relaxation in their force-length relationship, respectively. To reproduce these physiological work-loop style contractions in the single cell preparations, various techniques have been developed using amphibian or mammalian cardiomyocytes. The most important procedure in these techniques is holding the cell ends in order to apply mechanical load. Frog cardiomyocytes are thin and compliant; therefore, they are suitable for holding the cell ends to stretch the cells and measure the twitch force. On the other hand, applying these techniques in the mammalian cardiomyocytes has been challenging because of their short and thick shape and stiffness that makes holding cell ends difficult. Recently, carbon fiber technique has been introduced to attach the mammalian cell ends by electric statics. Since then, this technique has been modified by many researchers in order to improve the cell end attachment. To reproduce the work-loop style contractions, the afterload should be controlled using the force or length feedback control in each of the four phases separately. For this purpose, real-time feedback control is ideal; however, the relatively low signal-to-noise ratio of force/length signal in the carbon fiber technique makes real-time feedback control difficult. Instead, adaptive feedback or feed-forward approach enables it. Recently developed new optical force transducer using laser interferometry allowed force/length measurement with low enough noise for real-time feedback control.
The author thanks to Dr. Yohei Yamaguchi, Dr. Toshiyuki Kaneko and Dr. Anastasia Khokhlova for sharing their wide experience in single cell mechanics experiments.
- 8.Delnoy, P. P. H. M., Ottervanger, J. P., Luttikhuis, H. O., Vos, D. H. S., Elvan, A., Ramdat Misier, A. R., et al. (2009). Pressure-volume loop analysis during implantation of biventricular pacemaker/cardiac resynchronization therapy device to optimize right and left ventricular pacing sites. European Heart Journal, 30, 797–804.CrossRefGoogle Scholar
- 10.Gannier, F., White, E., Garnier, D., & Le Guennec, J. Y. (1996). A possible mechanism for large stretch-induced increase in [Ca2+]i in isolated guinea-pig ventricular myocytes. Cardiovascular Research, 32, 158–167.Google Scholar
- 11.Guyton, A. C., & Hall, J. E. (2006). Textbook of medical physiology (11th ed.). Philadelphia: Elsevier Saunders.Google Scholar
- 20.Le Guennec, J. Y., Peineau, N., Argibay, J. A., Mongo, K. G., & Garnier, D. (1990). A new method of attachment of isolated mammalian ventricular myocytes for tension recording: length dependence of passive and active tension. Journal of Molecular and Cellular Cardiology, 22, 1083–1093.CrossRefGoogle Scholar
- 21.Nishimura, S., Yasuda, S., Katoh, M., Yamada, K. P., Yamashita, H., Saeki, Y., et al. (2004). Single cell mechanics of rat cardiomyocytes under isometric, unloaded, and physiologically loaded conditions. American Journal of Physiology Heart and Circulatory Physiology, 287, H196–H202.CrossRefGoogle Scholar
- 36.Tung, L., & Morad, M. (1988). Contractile force of single heart cells compared with muscle strips of frog ventricle. American Journal of Physiology, 255, H111–H120.Google Scholar
- 37.White, E., Le Guennec, J. Y., Nigretto, J. M., Gannier, F., Argibay, J. A., & Garnier, D. (1993). The effects of increasing cell length on auxotonic contractions; membrane potential and intracellular calcium transients in single guinea-pig ventricular myocytes. Experimental Physiology, 78, 65–78.CrossRefGoogle Scholar
- 39.Yasuda, S. I., Sugiura, S., Kobayakawa, N., Fujita, H., Yamashita, H., Katoh, K., et al. (2001). A novel method to study contraction characteristics of a single cardiac myocyte using carbon fibers. American Journal of Physiology Heart and Circulatory Physiology, 281, H1442–H1446.CrossRefGoogle Scholar
- 40.Yasuda, S., Sugiura, S., Yamashita, H., Nishimura, S., Saeki, Y., Momomura, S., et al. (2003). Unloaded shortening increases peak of Ca2+ transients but accelerates their decay in rat single cardiac myocytes. American Journal of Physiology Heart and Circulatory Physiology, 285, H470–H475.CrossRefGoogle Scholar