Effects of hypertonic solutions on contraction of frog tonic muscle fibers.
Effects of hypertonic solutions on contraction of frog tonic muscle fibers.
复制标题
高渗溶液对青蛙强直肌纤维收缩的影响。
DOI：
10.1152/ajpcell.1984.246.1.c148
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发表时间：
1984
期刊：
影响因子：
--
通讯作者：
Gordon,AM
中科院分区：
文献类型：
--
作者：
Godt,RE;Kirby,AC;Gordon,AM
在来自青蛙髂腓肌的小束强直肌纤维中研究了溶液高渗性对收缩的影响。用高 K+ 溶液激活肌肉，该溶液的渗透压随三（羟甲基）氨基甲烷丙酸盐的增加而增加。峰值钾收缩力随张力单调下降，并且在渗透压为对照林格氏渗透压摩尔浓度的 2.5 或 3 倍的溶液中为零。通过将培养基中的 Ca2+ 增加 10 倍（至 20 mM）和/或通过添加咖啡因 (10-20 mM) 来增加所研究的所有张力（小于或等于 3 X Ringer）的挛缩力。然而，随着张力的增加，这种增强的力量也会减弱。从这些纤维束中取出的单个机械剥皮的强直纤维的力被 Ca2+ 在与抽搐纤维相同的浓度范围内激活。此外，最大Ca2+激活力（单位横截面积归一化）在带皮强直纤维和抽搐纤维中是相似的。正如之前在抽搐纤维中所示，当离子强度增加时，最大 Ca2+ 激活力降低。这些数据表明，与抽搐纤维一样，张力的增加通过增加细胞内离子强度来抑制张力纤维的收缩，从而抑制收缩装置产生力的能力。然而，与抽搐纤维不同，兴奋-收缩耦合过程的破坏可能在强直纤维的高渗性作用中发挥更重要的作用。
The influence of solution hypertonicity on contraction was studied in small bundles of tonic muscle fibers from the iliofibularis muscle of the frog Rana pipiens. Muscles were activated with high-K+ solutions that had osmolalities which were increased with tris(hydroxymethyl)aminomethanepropionate. Peak potassium contracture force decreased monotonically with tonicity and was zero in solutions with 2.5 or 3 times the osmolality of control Ringer. Contracture force at all tonicities studied (less than or equal to 3 X Ringer) was increased by increasing Ca2+ in the media 10-fold (to 20 mM) and/or by adding caffeine (10-20 mM). Nevertheless, this potentiated force also was diminished as tonicity increased. Force of single, mechanically skinned tonic fibers taken from these bundles was activated by Ca2+ over the same concentration range as that of twitch fibers. Moreover, maximal Ca2+-activated force, normalized per cross-sectional area, was similar in skinned tonic and twitch fibers. As was shown previously in twitch fibers, maximal Ca2+-activated force was decreased when ionic strength was increased. These data suggest that, as with twitch fibers, increased tonicity depresses contraction of tonic fibers by increasing the intracellular ionic strength, which in turn inhibits the ability of the contractile apparatus to generate force. Unlike twitch fibers, however, disruption of the excitation-contraction coupling process probably plays a more significant role in the action of hypertonicity on tonic fibers.