期刊
AMERICAN JOURNAL OF PHYSIOLOGY-CELL PHYSIOLOGY
卷 283, 期 1, 页码 C42-C47出版社
AMER PHYSIOLOGICAL SOC
DOI: 10.1152/ajpcell.00416.2001
关键词
force potentiation; excitation contraction coupling; mechanical output; skeletal muscle; Ca2+
A brief high-frequency burst of action potentials results in a sustained force increase in skeletal muscle. The present study investigates whether this force potentiation is the result of a sustained increase of the free myoplasmic [Ca2+] ([Ca2+](i)). Single fibers from mouse flexor brevis muscles were stimulated with three impulses at 150 Hz (triplet) at the start of a 350-ms tetanus or in the middle of a 700-ms tetanus; the stimulation frequency of the rest of the tetanus ranged from 20 to 60 Hz. After the triplet, force was significantly (P < 0.05) increased between 17 and 20% when the triplet was given at the start of the tetanus and between 5 and 18% when the triplet was given in the middle (n = 7). However, during this potentiation, [Ca2+](i) was not consistently increased. Hence, the increased force following a high-frequency burst is likely due to changes in the myofibrillar properties.
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