Irving M, Maylie J, Sizto N L, Chandler W K
J Gen Physiol. 1987 Jan;89(1):1-40. doi: 10.1085/jgp.89.1.1.
This article describes a new apparatus for making simultaneous optical measurements on single muscle fibers at three different wavelengths and two planes of linear polarization. There are two modes of operation: mode 1 measures the individual absorbances of light linearly polarized along and perpendicular to the fiber axis, and mode 2 measures retardation (or birefringence) and the average of the two absorbance components. Although some intact frog twitch fibers were studied, most experiments used cut fibers (Hille, B., and D. T. Campbell. 1976. Journal of General Physiology. 67:265-293) mounted in a double-Vaseline-gap chamber (Kovacs, L., E. Rios, and M. F. Schneider. 1983. Journal of Physiology. 343:161-196). The end-pool segments were usually exposed for 2 min to 0.01% saponin. This procedure, used in subsequent experiments to make the external membranes in the end pools permeable to Ca indicators (Maylie, J., M. Irving, N. L. Sizto, G. Boyarsky, and W. K. Chandler. 1987. Journal of General Physiology. 89:145-176; Maylie, J., M. Irving, N. L. Sizto, and W. K. Chandler. 1987. Journal of General Physiology. 89:41-143), was routinely employed so that all our cut fiber results would be comparable. A simple method, which does not require microelectrodes, allowed continual estimation of a fiber's membrane (rm) and internal longitudinal (ri) resistances as well as the external resistance (re) under the Vaseline seals. The values of rm and ri obtained from cut fibers with this method agree reasonably well with values obtained from intact fibers using microelectrode techniques. Optical measurements were made on resting and action potential-stimulated fibers. The intrinsic fiber absorbance, defined operationally as log10 of the ratio of incident light to transmitted light intensity, was similar in intact and cut preparations, as were the changes that accompanied stimulation. On the other hand, the resting birefringence and the peak of the active change in cut fibers were, respectively, only 0.8 and 0.7 times the corresponding values in intact fibers. Both the amplitude and the half-width of the active retardation signal increased considerably during the time course of cut fiber experiments; a twofold increase in 2 h was not unusual. Such changes are probably due to a progressive alteration in the internal state of the cut fibers.
本文介绍了一种新装置，可对单根肌纤维在三种不同波长和两个线偏振平面上进行同步光学测量。该装置有两种操作模式：模式1测量沿纤维轴方向和垂直于纤维轴方向线性偏振光的各自吸光度，模式2测量延迟（或双折射）以及两个吸光度分量的平均值。虽然对一些完整的青蛙抽搐纤维进行了研究，但大多数实验使用的是置于双凡士林间隙室中的切断纤维（希勒，B.，和D.T.坎贝尔。1976年。《普通生理学杂志》。67:265 - 293）（科瓦奇，L.，E.里奥斯，和M.F.施奈德。1983年。《生理学杂志》。343:161 - 196）。末端池段通常暴露于0.01%的皂角苷中2分钟。在后续实验中使用该程序使末端池中的外部膜对钙指示剂具有通透性（梅利，J.，M.欧文，N.L.西佐，G.博亚尔斯基，和W.K.钱德勒。1987年。《普通生理学杂志》。89:145 - 176；梅利，J.，M.欧文，N.L.西佐，和W.K.钱德勒。1987年。《普通生理学杂志》。89:41 - 143），该程序被常规采用，以便我们所有切断纤维的结果具有可比性。一种不需要微电极的简单方法可以连续估计纤维的膜电阻（rm）、内部纵向电阻（ri）以及凡士林密封下的外部电阻（re）。用这种方法从切断纤维获得的rm和ri值与使用微电极技术从完整纤维获得的值相当吻合。对静息和动作电位刺激的纤维进行了光学测量。固有纤维吸光度在操作上定义为入射光与透射光强度之比的常用对数，在完整和切断的标本中相似，刺激时伴随的变化也相似。另一方面，切断纤维的静息双折射和活动变化峰值分别仅为完整纤维相应值的0.8倍和0.7倍。在切断纤维实验过程中，活动延迟信号的幅度和半高宽都显著增加；2小时内增加两倍并不罕见。这种变化可能是由于切断纤维内部状态的逐渐改变所致。
