Contractile activation in myotomes from developing larvae of Xenopus laevis.
Contractile activation in myotomes from developing larvae of Xenopus laevis.
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非洲爪蟾发育中幼虫肌节的收缩激活。
DOI：
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发表时间：
1986
期刊：
影响因子：
--
通讯作者：
C. L. Huang
中科院分区：
文献类型：
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作者：
C. L. Huang
研究了不同灌注液对非洲爪蟾（Xenopus laevis）幼体肌组发育的影响。子宫收缩是由含有高浓度钾离子的等渗溶液在24期以后的胚胎中引起的。这些细胞在5 - 10秒内发育，在20 - 30秒内灭活。缩窄准备时挛缩持续存在。第26期和第34期胚胎估计机械阈值处的K+浓度分别约为30和20 mM。K+浓度分别为78和48 mM时活性最高。溶性离子硫氰酸盐（10 mM）增强K+收缩，使K+浓度阈值降低。在3mm - Mn2+和无Ca2+溶液中，挛缩持续存在，机械阈值不变。2 mM‐丁卡因可逆地消除K+挛缩。3和20 mM - K+的静息电位比较证实，静息电位对外部K+浓度仍然敏感，无论是在对照、含丁卡因或低Ca2+洗浴溶液中。咖啡因（10‐20 mM）从24期开始引起持续的宫缩。咖啡因敏感性在26 - 28阶段最大，然后在33 - 36阶段出现下降。这些观察结果表明，在非洲爪蟾胚胎中，兴奋-收缩耦合机制与完成的肌节同时发育，接近第24期。然后，收缩的激活呈现成人模式，包括细胞内激活剂储存的电压依赖性释放，独立于细胞外Ca2+的进入。
Contractile activation in response to application of different perfusing solutions was observed in developing myotomes from larvae of Xenopus laevis. Contractures resulted from treatment with isotonic solutions containing high K+ concentrations in myotomes from embryos from stage 24 onwards. These developed over 5‐10 s and inactivated over 20‐30 s. Contractures persisted in curarized preparations. The applied K+ concentrations at the estimated mechanical threshold in embryos at stages 26 and 34 were about 30 and 20 mM respectively. Maximum activity was achieved at K+ concentrations of 78 and 48 mM respectively. The lyotropic ion thiocyanate (10 mM) potentiated K+ contractures, and shifted the threshold K+ concentration to lower values. Contractures persisted in the presence of 3 mM‐Mn2+ and in Ca2+‐free solutions, with unaltered mechanical thresholds. K+ contractures were reversibly abolished by 2 mM‐tetracaine. Comparisons of resting potentials in 3 and 20 mM‐K+ confirmed that the resting potential remained sensitive to external K+ concentration, whether in control, tetracaine‐containing, or low‐Ca2+ bathing solutions. Caffeine (10‐20 mM) caused sustained contractures from stage 24 onwards. Caffeine sensitivity was greatest at stages 26‐28, then appeared to decline at stages 33‐36. These observations suggest that mechanisms for excitation‐contraction coupling develop in Xenopus embryos at the same time as do completed sarcomeres, close to stage 24. Activation of contraction then assumes the adult pattern, involving voltage‐dependent release of the intracellular store of activator, independent of entry of extracellular Ca2+.
丁卡因对青蛙骨骼肌纤维中电荷运动和钙信号的影响。
DOI：
10.1073/pnas.80.5.1477
发表时间：
1983
影响因子：
11.1
作者：
Vergara,J;Caputo,C
通讯作者：
Caputo,C