van Lunteren E, Vafaie H, Salomone R J
Department of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA.
Respir Physiol. 1995 Jan;99(1):113-25. doi: 10.1016/0034-5687(94)00077-d.
We hypothesized that aging is associated with alterations in pharyngeal muscle structural and contractile properties. Sternohyoid and geniohyoid muscles from young (3-4 months) and old (20-21 months) Fischer 344 rats were compared with diaphragm muscle. The pharyngeal muscles had significantly lower proportions of slow oxidative (SO) fibers compared to the diaphragm, and the percentage of fast glycolytic (FG) fibers was significantly higher in the sternohyoid than in both the geniohyoid and the diaphragm. With senescence, there was a small but significant increase in the proportion of FG fibers and a corresponding reduction in the proportion of fast oxidative glycolytic (FOG) fibers in all three muscles. The sternohyoid muscle had significantly faster isometric contractile kinetics and lower fatigue indexes than the diaphragm. Aging was associated with significant worsening of sternohyoid endurance, but no significant alterations in sternohyoid twitch kinetics or diaphragm properties. These results indicate that in rats the pharyngeal dilator muscles have larger proportions of fast fibers, fast contractile kinetics and worse endurance than the diaphragm. Furthermore, aging was associated with a shift to a higher proportion of FG fibers with a concomitant reduction in proportion of FOG fibers, as well as a decline in pharyngeal muscle endurance.
我们推测衰老与咽肌结构和收缩特性的改变有关。将年轻（3 - 4个月）和年老（20 - 21个月）的Fischer 344大鼠的胸骨舌骨肌和颏舌骨肌与膈肌进行比较。与膈肌相比，咽肌中慢氧化（SO）纤维的比例显著更低，且胸骨舌骨肌中快糖酵解（FG）纤维的百分比显著高于颏舌骨肌和膈肌。随着衰老，所有三块肌肉中FG纤维的比例都有小幅但显著的增加，同时快氧化糖酵解（FOG）纤维的比例相应降低。胸骨舌骨肌的等长收缩动力学明显比膈肌快，疲劳指数也更低。衰老与胸骨舌骨肌耐力的显著恶化有关，但胸骨舌骨肌的抽搐动力学或膈肌特性没有显著改变。这些结果表明，在大鼠中，咽扩张肌比膈肌具有更大比例的快肌纤维、更快的收缩动力学和更差的耐力。此外，衰老与FG纤维比例的增加以及FOG纤维比例的相应减少有关，同时咽肌耐力下降。
