抽象的
咽部和隔膜肌肉合同并在协同作用中放松,这就是为什么它决定在整个负荷连续内比较它们的机械性能。还研究了疲劳的影响。体外研究大鼠胸蛋白(SH; n = 10)和隔膜(D; n = 10)的等渗机械。在从零负载到等距的肌肉收缩的肌肉中测量力和长度。记录了最大等距张力(PMAX),峰机械工作(WMAX),最大卸载缩短速度(VZL)和机械效率(EFF(最大))。数据在基线和疲劳后获得。S.H muscles had a lower Pmax (96.0+/-13.7 versus 119.5+/-22.7 mN x mm(-2); p<0.05), a lower Wmax (5.5+/-1.2 versus 8.0+/-2.1 mJ x g(-1); p<0.01), a lower eff(max) (56.0+/-6.9 versus 62.6+/-5.8%; p<0.05) and a higher vzL (4.8+/-0.4 versus 3.4+/-0.4 initial length (L0) x s(-1); p<0.001) than D muscles. Wmax occurred at a higher relative load in SH (40% Pmax) than in D (30% Pmax). Fatigue did not modify eff(max) in SH muscles, whereas it significantly improved eff(max) in D muscles. These findings suggest that under control conditions, economy of force generation was less efficient in sternohyoid than in diaphragm muscles. Fatigue in sternohyoid muscles induced unfavourable mechanical behaviour. This may partly explain pharyngeal dilator muscle failure in the presence of increased loads. Whether these findings are relevant to human sleep apnoea syndrome has yet to be determined.