Bonilla M, García M C, Orkand P M, Zuazaga C
Department of Physiology and Biophysics, ENCB del IPN, Mexico, D.F.
Tissue Cell. 1992;24(4):525-35. doi: 10.1016/0040-8166(92)90068-i.
Examination of the ultrastructure and mechanical activation of the ventro-abdominal flexor muscle of the freshwater crustacean Atya lanipes shows that the fibers are of the long sarcomere, tonic type. The fibers possess an ample and well-organized internal membrane system, with extensive regions of T/SR dyad contacts near the ends of the A bands. An orbit of 10-12 thin filaments surrounds each thick filament. The lanthanum tracer method reveals a highly regular organization of the T-system, Z-tubules, and multiple internal clefts. Tension generation responds to extracellular potassium in a concentration dependent manner and is very slow. Mechanical activation is strictly dependent on extracellular Ca2+, even though these muscle fibers do not generate Ca2+ currents when depolarized. Tension development responds to caffeine and is also dependent on extracellular Na+, suggesting that Ca2+ release from the SR and Ca2+ influx via the Na/Ca exchanger intervene in mechanical activation.
对淡水甲壳类动物阿蒂亚长脚蟹腹侧腹肌的超微结构和机械激活的研究表明，其纤维属于长肌节、紧张型。这些纤维拥有丰富且组织良好的内膜系统，在A带末端附近有广泛的T/SR二联体接触区域。每条粗肌丝周围有10 - 12条细肌丝环绕。镧示踪法揭示了T系统、Z小管和多个内部裂隙的高度规则组织。张力产生以浓度依赖的方式对细胞外钾作出反应，且非常缓慢。机械激活严格依赖于细胞外Ca2+，尽管这些肌纤维在去极化时不产生Ca2+电流。张力发展对咖啡因有反应，并且也依赖于细胞外Na+，这表明Ca2+从肌浆网释放以及通过Na/Ca交换体的Ca2+内流参与了机械激活。
