TIME- AND Na-DEPENDENT EFFECTS OF Ca DEPLETION ON POTASSIUM CONTRACTURE IN FROG TWITCH MUSCLE FIBER

DOI Web Site PubMed

書誌事項

タイトル別名
  • Time and Na Dependent Effects of Ca Dep

この論文をさがす

抄録

The effect of the extracellular Ca depletion on potassium contracture was investigated in single fibers isolated from frog semitendinosus muscle mainly in relation to its time and Na dependency. The shortening of plateau duration and the increase in the rate of relaxation of the potassium contracture appeared within 3-5 sec and 15sec, respectively, after the fiber was immersed in Ca-free Na Ringer solution containing 1mm ethylene glycol bis (β-aminoethyl ether)-N, N'-tetraacetic acid (EGTA)(EGTA-Na Ringer solution) or Ca-free choline Ringer solution containing 1mm EGTA (EGTA-choline Ringer solution). These effects were independent of the presence or absence of extracellular Na. In EGTA-Na Ringer solution, the potassium contracture tension was inhibited only by about 20% after 20-90min andwas abolished after 120min. The inhibition of the peak tension was accelerated by the depletion of extracellular Na;in EGTA-choline Ringer solution, the tension was gradually inhibited by about 20 during the first 7min and abolished after 10-12min. When the peak tension of potassium contracture was abolished in EGTA-choline Ringer solution, the depolarization by Ca depletion was about 10mV and the caffeine contracture was sufficiently produced. The results suggest that the inhibition of the potassium contracture tension in EGTA-choline Ringer solution is due to the dissociation of excitationcontraction coupling. On the basis of these results, an aspect of the inactivation of the potassium contracture was proposed.

収録刊行物

キーワード

詳細情報 詳細情報について

問題の指摘

ページトップへ