CONTRACTILE PROPERTIES AND TEMPERATURE SENSITIVITY OF THE EXTRAOCULAR-MUSCLES, THE LEVATOR AND SUPERIOR RECTUS, OF THE RABBIT
CONTRACTILE PROPERTIES AND TEMPERATURE SENSITIVITY OF THE EXTRAOCULAR-MUSCLES, THE LEVATOR AND SUPERIOR RECTUS, OF THE RABBIT
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DOI：
10.1113/jphysiol.1994.sp020073
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发表时间：
1994-03-01
影响因子：
5.5
通讯作者：
WILLIAMS, DA
中科院分区：
文献类型：
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作者：
FRUEH, BR;HAYES, A;WILLIAMS, DA
1.对兔上直肌和上睑提肌两种眼外肌的收缩和抗疲劳特性、收缩温度敏感性(10-37℃)和组织化学纤维类型进行了测定。在室温(20℃)下，提肌表现出与哺乳动物快速抽动肢体肌肉相似的收缩特征(抽动反应的峰值时间、一半松弛时间和抽动与破伤风的力量比)。然而，标准化的抽搐和强直力水平明显低于四肢肌肉。在20℃的温度下，上直肌表现出比提升肌更快的收缩速度，但产生的最大力量水平低于提升肌。上直肌的抽动反应呈双相松弛相。这一反应不是由于上直肌中存在的非抽动(紧张性)纤维所致，因为在肌肉刺激过程中应用心得安不会对其产生影响。在强直肌和提肌的强直力反应中，上直肌和提肌的疲劳程度明显低于快速抽动肢体肌肉对疲劳电刺激方案的反应。提肌的抗疲劳能力明显强于上直肌。两个眼外肌的力量反应对温度(10-37摄氏度)的依赖与四肢骨骼肌相似。肌球蛋白ATPase染色显示，肌球蛋白ATPase染色显示上直肌和提肌有较高比例的快抽动肌纤维(II型)。琥珀酸脱氢酶活性表明，这些肌肉表现出很高的氧化能力，染色强度典型的是四肢肌肉的I型或IIA型纤维。这些结果强调了哺乳动物眼外肌的形态和功能的复杂性。快速收缩特性和高氧化能力的结合使这些肌肉非常适合它们在眼球/眼皮运动中的作用。
1. Contractile and fatigue-resistance characteristics, temperature sensitivity (10-37-degrees-C) of contraction, and histochemical fibre types were determined for two of the extraocular muscles, the superior rectus and levator palpebrae superioris (levator), of the rabbit.2. The levator displayed similar contractile characteristics (time to peak, half-relaxation time of twitch response, and twitch-tetanus force ratio) to mammalian fast-twitch limb muscle at room temperature (20-degrees-C). However, normalized twitch and tetanic force levels were significantly less than those found in limb muscle. The superior rectus displayed the characteristics of even faster contraction than the levator at 20-degrees-C, but generated lower maximum force levels than the levator.3. The twitch response of the superior rectus showed a biphasic relaxation phase. This response was not due to non-twitch (tonic) fibres present in the superior rectus as it was unaffected by propranolol application during muscle stimulation.4. The superior rectus and levator displayed significantly less fatigue in the tetanic force response than fast-twitch limb muscles did in response to a fatiguing electrical stimulation protocol. The levator was significantly more fatigue resistant than the superior rectus.5. The force responses of both extraocular muscles displayed a similar dependence on temperature (10-37-degrees-C) to limb skeletal muscles.6. The superior rectus and levator exhibited a high proportion of fast-twitch muscle fibres (type II) as shown by myosin ATPase staining. Succinate dehydrogenase activity indicated that these muscles showed a high oxidative capacity, with a staining intensity typical of type I or type II A fibres of limb muscles.7. The results emphasize the morphological and functional complexity of mammalian extraocular muscles. The combination of very fast contractile properties with high oxidative capacity make these muscles well suited to their role in eye/eyelid movement.