Cecchi G, Colomo F, Poggesi C, Tesi C
Dipartimento di Scienze Fisiologiche, Università degli Studi di Firenze, Italy.
Pflugers Arch. 1993 Apr;423(1-2):113-20. doi: 10.1007/BF00374968.
An apparatus for studying the mechanics of isolated frog heart myocytes is described. The cells are held horizontal in a through of Ringer solution by means of two suction micropipettes. Myocyte force is measured with an opto-electronic system recording the deflection of the tip of one micropipette, which acts as a cantilever force probe. The force probes are selected for compliance according to the force a myocyte is expected to develop in a given condition, so as to limit myocyte shortening during force development to no more than 1% of the slack cellular length (l0). The other micropipette, which is stiff relative to the forces measured, is mounted on an electromagnetic-loudspeaker motor by which controlled-velocity length changes, of preset size and in either direction, are imposed on myocytes. The force transducer has a sensitivity of 5-10 mV/nN, with a frequency response of 700-900 Hz in Ringer solution and a resolution of 0.5-1 nN. The motor with a suction micropipette can complete controlled-velocity length ramps within 1.5-2.0 ms, across a range of +/- 100 microns at a resolution of 8.0 nm. These values correspond, for frog-heart myocytes 200 microns and 400 microns long, to 25%-50% l0 and 0.002%-0.004% l0 respectively.
本文描述了一种用于研究离体青蛙心脏心肌细胞力学特性的装置。细胞通过两个吸液微吸管水平固定在林格氏液槽中。心肌细胞的力通过一个光电系统测量，该系统记录作为悬臂力探针的一个微吸管尖端的偏转。根据预期心肌细胞在给定条件下产生的力来选择力探针的顺应性，以便在力产生过程中将心肌细胞的缩短限制在松弛细胞长度（l0）的1%以内。另一个相对于所测量的力较硬的微吸管安装在一个电磁扬声器电机上，通过该电机可以向心肌细胞施加预设大小和任意方向的受控速度长度变化。力传感器的灵敏度为5 - 10 mV/nN，在林格氏液中的频率响应为700 - 900 Hz，分辨率为0.5 - 1 nN。带有吸液微吸管的电机能够在1.5 - 2.0毫秒内完成受控速度长度斜坡变化，范围为±100微米，分辨率为8.0纳米。对于长度为200微米和400微米的青蛙心脏心肌细胞，这些值分别对应于25% - 50% l0和0.002% - 0.004% l0。
