Tung L, Morad M
Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21205.
Am J Physiol. 1988 Jul;255(1 Pt 2):H111-20. doi: 10.1152/ajpheart.1988.255.1.H111.
Single heart cells were obtained from frog ventricle with an enzymatic dispersion technique. Isometric contractile force was measured in these cells by an ultrasensitive force transducer and compared with that generated by multicellular muscle strips under similar conditions. The shape of the single-cell twitch was qualitatively similar to that obtained in intact tissue; however, the time to peak was generally shorter, and the falling phase was prolonged in the single cell compared with the muscle strip. The single-cell contractile force was measured in response to alterations in stimulus rate, resting length, and extracellular Ca2+ concentration [Ca2+]o or by addition of epinephrine; in all cases, the force response resembled the physiological response seen in the muscle strip. However, at a constant stimulation rate, the steady-state amplitude of the single-cell twitch exhibited beat-to-beat variations under all conditions tested, whereas that of the muscle strip was essentially constant. These results may prove to be useful in assessing the suitability of the single-cell preparation as a model for the intact tissue.
采用酶分散技术从青蛙心室获取单个心肌细胞。通过超灵敏力传感器测量这些细胞的等长收缩力，并与在类似条件下多细胞肌条产生的收缩力进行比较。单细胞收缩期的形状在定性上与在完整组织中获得的相似；然而，与肌条相比，单细胞达到峰值的时间通常更短，且下降期延长。测量单细胞收缩力以响应刺激频率、静息长度、细胞外钙离子浓度[Ca2+]o的变化或通过添加肾上腺素；在所有情况下，力响应类似于在肌条中观察到的生理反应。然而，在恒定刺激频率下，在所有测试条件下，单细胞收缩期的稳态幅度逐搏变化，而肌条的稳态幅度基本恒定。这些结果可能有助于评估单细胞制备作为完整组织模型的适用性。
