抄録
The intrinsic mechanical properties of intact cells are basically important themselves and also important to explain those of muscle bundles, since the muscle bundles are comprised of infinitely many cells. The mechanical properties of single cardiac cells enzymatically isolated from rat ventricles were studied. Both ends of single cells were firmly and stably glued to the glass-fiber needles (diameter of 30 μm) coated with poly-L-lysine to measure the length change or the force by the handmade electrostatic force-length transducer. The absolute forces were measured in resting state, which is considered to express the parallel elastic element. The resting force seemed to increase with the cell length. The forces were also measured during twitch-contractions. The measured active forces were typically more than 1 μN. The shortening velocity, which is considered to express the contractile element, was measured by various methods, namely, the quick release method (QR), the afterload contraction method (AL) and the ramp-load release method (RAMP) applied the linear load decrement from the time of peak tension developed. The maximal shortening velocities (Vmax) were about 2.6 cell length/sec (CL/s) by QR, 0.9 CL/s by AL. The ramp rate dependent Vmax was 0.5 CL/s by RAMP with the ramp rate of -10 μN/sec. The length change was related rather linearly to the tension change with the decay rate of about 22 μm/μN, which is considered to express the series elastic element. Finally, the main three mechanical elements of single cardiac cells were obtained. [Jpn J Physiol 54 Suppl:S121 (2004)]
