EFFECT OF LOW EXTRACELLULAR CALCIUM AND RYANODINE ON MUSCLE-CONTRACTION OF THE MOUSE DURING POSTNATAL-DEVELOPMENT
EFFECT OF LOW EXTRACELLULAR CALCIUM AND RYANODINE ON MUSCLE-CONTRACTION OF THE MOUSE DURING POSTNATAL-DEVELOPMENT
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DOI：
10.1139/y91-190
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发表时间：
1991-09-01
影响因子：
2.1
通讯作者：
NEERING, IR
中科院分区：
文献类型：
--
作者：
DANGAIN, J;NEERING, IR
我们研究了低钙溶液、Co2+和Ryanodine对发育中的小鼠EDL肌的等长张力和收缩速度的影响。年轻肌肉(出生后7-14天)的抽动反应对降低[Ca~(2+)]o比发育较充分的肌肉(出生后22-35天)更敏感。中年组(出生后15-21天)的EDL肌反应介于其他两组之间。总体而言，低[Ca~(2+)]o·无Ca~(2+)溶液在年轻和“老年”肌纤维上分别引起7.95 mV和9.25 mV的去极化，加速了单次抽动收缩的时间进程。Krebs溶液中钴离子(5 MM)的存在与无钙Krebs溶液在减少不同年龄组EDL肌的等长抽动和强直性张力方面具有相似的效果。相比之下，无钙溶液的收缩时间在接触含CO2+溶液后并未发生缩短。最后，与发育较充分的肌肉(出生后22-35天)相比，年轻的肌肉(出生后7-14天)对兰诺定对抽动的抑制作用不那么敏感。综上所述，我们的结果表明，从出生到成熟，用于收缩过程的钙利用谱有一个逐渐变化的过程。
We have examined the effects of low Ca2+ solutions, Co2+, and ryanodine on the isometric tension and contraction speed of isolated, developing mouse EDL muscles. Twitch responses of young muscles (7-14 days postnatal) were more sensitive to lowered [Ca2+]o than those of more fully developed muscles (22-35 days postnatal). Responses of EDL muscles from a middle-aged group (15-21 days postnatal) were intermediate between the two other groups. Overall, the time course of contraction in a single twitch was accelerated by low [Ca2+]o. Ca2+-free solution induced a 7.95 and 9.25 mV depolarization in young and "old" muscle fibres, respectively. The presence of cobalt ions (5 mM) in the Krebs solution had a similar effect as Ca2+-free Krebs in terms of reduction of the isometric twitch and tetanic tensions of EDL muscles from the various age groups. In contrast, the shortening of the contraction time seen with Ca2+-free solution did not take place following exposure to Co2+-containing solutions. Finally, young (7-14 days postnatal) muscles were less sensitive to the inhibitory action of ryanodine on the twitch compared with more fully developed muscles (22-35 days postnatal). Taken together, our results indicate that from birth to maturity, there is a gradual change in the spectrum of calcium utilization for the contractile process.