Excitation-Contraction Coupling in Barnacle Muscle Fibers: Does Calcium Entry Trigger Contraction Directly?
It is well known that mechanical activation of muscle from both vertebrates and invertebrates is triggered by an elevation of the concentration of free-calcium in the sarcoplasm. In skeletal muscle fibers from vertebrates this ion is actively transported into the sarcoplasmic reticulum (SR) and released at the level of the terminal cisternae of the SR following the regenerative depolarization of the transverse tubular membrane.(1)) However, the question of the origin of the calcium required for mechanical activation in invertebrate skeletal muscle has not been yet elucidated. (2)
KeywordsSingle Muscle Fiber Peak Tension Open Fiber Contractile Machinery Vertebrate Skeletal Muscle
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- 2.Caputo, C., and DiPolo, R., 1980, Does external calcium play any role in contractile activation?, J. Gen. Physiol. 75: 235–237.Google Scholar
- 4.Rojas, E., and Luxoro, M., 1974, Coupling between ion conductance changes and contraction in barnacle muscle fibers under membrane potential control, Actual. Neurophysiol. 10: 159–169.Google Scholar
- 14.Luxoro, M., and Nassar-Gentina, V., 1984, Potassium-induced depolarizations and generation of tension in barnacle muscle fibers: Effects of external calcium, strontium, and barium, Quart. J. Exp. Physiol. 69: 235–243.Google Scholar
- 17.Nassar, V., Rojas, E., Carrasco, M. A., and Luxoro, M., 1987, Acoplamiento excitacion-contrac-cion en musculo de crustaceo, Arch. Biol. Med. Exp. 20: R154.Google Scholar