Pemrick S M, Edwards C
J Gen Physiol. 1974 Nov;64(5):551-67. doi: 10.1085/jgp.64.5.551.
Glycerol-extracted rabbit psoas muscle fibers were impaled with KCl-filled glass microelectrodes. For fibers at rest-length, the potentials were significantly more negative in solutions producing relaxation than in solutions producing either rigor or contraction; further the potentials in the latter two cases were not significantly different. For stretched fibers, with no overlap between thick and thin filaments, the potentials did not differ in the rigor, the relaxation, or the contraction solutions. The potentials measured from fibers in rigor did not vary significantly with the sarcomere length. For relaxed fibers, however, the potential magnitude decreased with increasing sarcomere length. The difference between the potentials measured for rigor and relaxed fibers exhibited a nonlinear relationship with sarcomere length. The potentials from calcium-insensitive fibers were less negative in both the rigor and the relaxation solutions than those from normal fibers. When calcium-insensitive fibers had been incubated in Hasselbach and Schneider's solution plus MgCl(2) or Guba-Straub's solution plus MgATP the potentials recorded upon impalement were similar in the rigor and the relaxation solution to those obtained from normal fibers in the relaxed state. It is concluded that the increase in the negative potential as the glycerinated fiber goes from rigor to relaxation may be due to an alteration in the conformation of the contractile proteins in the relaxed state.
用充满氯化钾的玻璃微电极刺入甘油抽提的兔腰大肌纤维。对于处于静息长度的纤维，在产生松弛的溶液中电位比在产生强直或收缩的溶液中显著更负；此外，后两种情况下的电位没有显著差异。对于拉伸的纤维，粗细肌丝之间没有重叠，在强直、松弛或收缩溶液中电位没有差异。从处于强直状态的纤维测得的电位随肌节长度没有显著变化。然而，对于松弛的纤维，电位大小随肌节长度增加而降低。强直纤维和松弛纤维测得的电位差与肌节长度呈非线性关系。在强直和松弛溶液中，钙不敏感纤维的电位比正常纤维的电位负性小。当钙不敏感纤维在哈塞尔巴赫和施奈德溶液加氯化镁或古巴 - 施特劳布溶液加镁 - 三磷酸腺苷中孵育后，刺入时记录的电位在强直和松弛溶液中与从处于松弛状态的正常纤维获得的电位相似。得出的结论是，当甘油化纤维从强直状态转变为松弛状态时负电位的增加可能是由于松弛状态下收缩蛋白构象的改变。
