Bagni M A, Cecchi G, Colomo F, Garzella P
Dipartimento di Scienze Fisiologiche, Università di Firenze, Italy.
J Muscle Res Cell Motil. 1992 Oct;13(5):516-22. doi: 10.1007/BF01737994.
The effects of 2,3-butanedione monoxime (BDM) on contraction characteristics were studied at 5 degrees C in single intact fibres isolated from the tibialis anterior muscle of the frog. The force-velocity relation was determined using the controlled-velocity method in either whole fibres or short fibre segments in which sarcomere shortening was measured by a laser light diffraction method. It is shown that 3 mM BDM decreases the speed of rise and the amount of tetanus tension, reduces the maximum velocity of shortening and increases the curvature of the force-velocity relation, as well as the value for the stiffness to tension ratio. BDM also slowed down the redevelopment of tetanus tension after a period of unloaded shortening both in fixed-end and in length-clamp conditions. In normal and in BDM-treated fibres length-clamping increased the speed of the initial rise of tetanus tension but not that of the recovery after shortening. The observed force-velocity data points were fitted by the Huxley (1957) equation. It was found that BDM produces a conspicuous decrease of the rate constant for crossbridge attachment. This effect, and also a reduction of the force per crossbridge, are responsible for the depression of the contractile characteristics produced by BDM.
在5摄氏度下，对从青蛙胫骨前肌分离出的单根完整肌纤维研究了2,3-丁二酮一肟（BDM）对收缩特性的影响。采用控制速度法，在完整肌纤维或短肌纤维段中测定力-速度关系，其中肌节缩短通过激光衍射法测量。结果表明，3 mM BDM降低了上升速度和强直张力大小，降低了最大缩短速度，增加了力-速度关系的曲率以及刚度与张力比值。在固定端和长度钳制条件下，BDM还减缓了一段无负荷缩短后强直张力的重新恢复。在正常和BDM处理的肌纤维中，长度钳制增加了强直张力初始上升速度，但未增加缩短后恢复速度。观察到的力-速度数据点用赫胥黎（1957）方程拟合。发现BDM使横桥附着的速率常数显著降低。这种效应以及每个横桥力的降低，是BDM导致收缩特性降低的原因。
