Enhanced neuromuscular transmission efficacy in overloaded rat plantaris muscle

被引:6
作者
Argaw, A
Desaulniers, P
Gardiner, PF
机构
[1] Univ Manitoba, Hlth Leisure & Human Performance, Res Inst, HLHP, Winnipeg, MB R3T 2N2, Canada
[2] Univ Manitoba, Spinal Cord Res Ctr, Max Bell Ctr, Winnipeg, MB R3T 2N2, Canada
[3] Univ Montreal, Dept Kinesiol, Montreal, PQ, Canada
关键词
endplate potential; neuromuscular junction; neuromuscular transmission efficacy; overloaded plantaris; synaptic transmission;
D O I
10.1002/mus.10535
中图分类号
R74 [神经病学与精神病学];
学科分类号
摘要
To better understand the effect of muscle hypertrophy on the physiological properties of transmitter release, we investigated neuromuscular transmission (NMT) efficacy in overloaded rat plantaris muscle in situ. In the overload group, following bilateral tenotomy of plantaris synergists, rats were confined to wheel-cages. Age-matched rats in the control group were confined to plastic cages. During the terminal experiment, muscle action potentials were blocked using It-conotoxin, and full-sized endplate potentials (EPPs) were recorded at 25, 50, and 75 Hz to determine their amplitude rundown. Quantal contents for the control and overload groups were 37.0 and 74.3, respectively (P <0.01). There was a significant group difference in EPP amplitude rundown at all frequencies examined, with increased rundown occurring in the overload group (P < 0.01). Cumulative quantal release was 139% and 153% higher in the overload group at 25 and 50 Hz, respectively (P < 0.05). Together, these data suggest the safety factor for NMT is increased by neuromuscular overload. Furthermore, these findings support and supplement previously reported activity-dependent improvements in NMT efficacy that are probably mediated via presynaptic adaptations.
引用
收藏
页码:97 / 103
页数:7
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