特布他林对力的影响和细胞内钙slow-twitch骨骼肌纤维的老鼠。
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哈TN, Posterino GS,莱尔兆瓦
特布他林对力的影响和细胞内钙slow-twitch骨骼肌纤维的老鼠。
Br J杂志。1999年4月,126 (8):1717 - 24。doi: 10.1038 / sj.bjp.0702482。
- PubMed ID
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10372813 (在PubMed]
- 文摘
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1。alpha2-adrenoceptor受体激动剂的效果,特布他林,研究同时测量力和细胞内自由钙([Ca2 +] i)完整的大鼠比目鱼肌肌肉纤维,和收缩蛋白功能和Ca2 +肌浆网的内容(SR)皮肤的纤维。2。特布他林(10 microM)没有显著影响我休息力或[Ca2 +]。接触特布他林增加indo-1比例的积分瞬态和抽搐力峰值37%。3所示。在sub-maximal (10 Hz)刺激频率,特布他林加速力放松但高度变量对强直力振幅的影响。相应的indo-1比瞬变明显更大,更快的衰减比控制。4所示。特布他林增加强直力在接近最大刺激频率(50赫兹)通过增加强直[Ca2 +]我。 Force relaxation was accelerated at this frequency with no significant change in the indo-1 ratio transient decay rate. 5. All of terbutaline's effects on force and indo-1 ratio transients in intact fibres were completely blocked and reversed by ICI 118551 (1 microM). 6. Mechanically skinned fibres isolated from intact muscles pre-treated with terbutaline showed no significant changes in SR Ca2+ content, myofilament [Ca2+]i-sensitivity or maximum force generating capacity. 7. The results suggest that terbutaline primarily modulates force by altering the amplitude and decay rate of the [Ca2+]i transient via phosphorylation of both the ryanodine receptor (RR) and the SR pump regulatory protein, phospholamban (PLB). The high variability of responses of slow-twitch muscles to beta2-agonists probably reflects individual differences in basal phosphorylation levels of PLB relative to that of RR.