The contractility of isolated muscles of the frog (and in some instances of the rat) was investigated at room temperature in Ringer's solutions containing homologous alkanoic acids (100 mM C4 to 0.4 mM C10). 2. Free fatty acids decrease the contraction amplitudes evoked by direct stimulation. The effects increase with concentration, exposure, and chain length of the fatty acids. In Ringer's solution the changes are totally or partly reversible. 3. The depression of contraction amplitude induced by free fatty acids is removed by small concentrations of caffeine (2--5 mM) in Ringer's solution. 4. Interactions of fatty acids with different structures of skeletal muscle (mitochondria, sarcolemma and membranes of sarcoplasmic vesicles) are discussed. The distinct effect of fatty acids on stimulated muscles and the importance of membranes in the regulation of the calcium ion concentration in the cytoplasm suggest that fatty acids interact with membrane lipids.
摘要
在室温下，于含有同源链烷酸（100 mM C4至0.4 mM C10）的林格氏液中，研究了青蛙（在某些情况下为大鼠）离体肌肉的收缩性。2. 游离脂肪酸会降低直接刺激所诱发的收缩幅度。这些效应会随着脂肪酸的浓度、暴露时间及链长而增加。在林格氏液中，这些变化完全或部分可逆。3. 在林格氏液中，低浓度的咖啡因（2 - 5 mM）可消除游离脂肪酸对收缩幅度的抑制作用。4. 讨论了脂肪酸与骨骼肌不同结构（线粒体、肌膜和肌浆小泡膜）之间的相互作用。脂肪酸对受刺激肌肉的显著影响以及膜在调节细胞质钙离子浓度中的重要性表明，脂肪酸与膜脂相互作用。
