Jaspers R T, Feenstra H M, Lee- de Groot M B, Huijing P A, van der Laarse W J
Instituut voor Fundamentele en Klinische Bewegingswetenschappen, Faculteit Bewegingswetenschappen, Vrije Universiteit, Amsterdam, The Netherlands.
Arch Physiol Biochem. 2001 Dec;109(5):410-7. doi: 10.1076/apab.109.5.410.11825.
Investigation of the mechanisms of muscle adaptation requires independent control of the regulating factors. The aim of the present study was to develop a serum-free medium to culture mature single muscle fibres of Xenopus laevis. As an example, we used the culture system to study adaptation of twitch and tetanic force characteristics, number of sarcomeres in series and fibre cross-section. Fibres dissected from m. iliofibularis (n = 10) were kept in culture at a fibre mean sarcomere length of 2.3 microm in a culture medium without serum. Twitch and tetanic tension were determined daily. Before and after culture the number of sarcomeres was determined by laser diffraction and fibre cross-sectional area (CSA) was determined by microscopy. For five fibres twitch tension increased during culture and tetanic tension was stable for periods varying from 8 to 14 days ('stable fibres'), after which fibres were removed from culture for analysis. Fibre CSA and the number of sarcomeres in series remained constant during culture. Five other fibres showed a substantial reduction in twitch and tetanic tension within the first five days of culture ('unstable fibres'). After 7-9 days of culture, three of these fibres died. For two of the unstable fibres, after the substantial force reduction, twitch and tetanic tension increased again. Finally at day 14 and 18 of culture, respectively, the tensions attained values higher than their original values. For stable fibres, twitch contraction time, twitch half-relaxation time and tetanus 10%-relaxation time increased during culture. For unstable fibres these parameters fluctuated. For all fibres the stimulus threshold fluctuated during the first two days, and then remained constant, even for the fibres that were cultured for at least two weeks. It is concluded that the present culture system for mature muscle fibres allows long-term studies within a well-defined medium. Unfortunately, initial tetanic and twitch force are poor predictors of the long-term behaviour of the fibres.
对肌肉适应性机制的研究需要对调节因子进行独立控制。本研究的目的是开发一种无血清培养基，用于培养非洲爪蟾的成熟单根肌纤维。例如，我们使用该培养系统来研究抽搐和强直力特性、串联肌节数量以及纤维横截面积的适应性。从髂腓肌（n = 10）分离出的纤维在无血清培养基中以平均肌节长度2.3微米的条件进行培养。每天测定抽搐和强直张力。培养前后通过激光衍射测定肌节数量，通过显微镜测定纤维横截面积（CSA）。对于五根纤维，培养期间抽搐张力增加，强直张力在8至14天的不同时间段内保持稳定（“稳定纤维”），之后将纤维从培养中取出进行分析。培养期间纤维CSA和串联肌节数量保持不变。另外五根纤维在培养的前五天内抽搐和强直张力大幅降低（“不稳定纤维”）。培养7 - 9天后，其中三根纤维死亡。对于两根不稳定纤维，在力大幅降低后，抽搐和强直张力再次增加。最终分别在培养的第14天和18天，张力达到高于其初始值的值。对于稳定纤维，培养期间抽搐收缩时间、抽搐半松弛时间和强直10%松弛时间增加。对于不稳定纤维，这些参数波动。对于所有纤维，刺激阈值在前两天波动，然后保持恒定，即使对于培养至少两周的纤维也是如此。结论是，目前用于成熟肌纤维培养的系统允许在明确界定的培养基中进行长期研究。不幸的是，初始强直和抽搐力并不能很好地预测纤维的长期行为。
