筋収縮に及ぼすADPの効果

概要

論文の詳細を見る
Muscle contraction is caused by actin and myosin filaments sliding past each other. The physiological minimum unit of contraction is called a "sarcomere". This sliding movement is caused by repeating the hydrolysis of adenosine triphosphate (ATP). The reaction cycle is generally explained as follows. ATP bound to myosin splits ADP (adenosine diphosphate) and Pi (phosphate) in myosin. Here, myosin affaches to actin. Subsequently, when Pi and ADP are released, myosin generates the force. Thus, myosin heads move on the actin filament toward the center of the sarcomere. However, the precise mechanism has not been solved. In this study, we focused on the step of ADP release, and investigated how the change in ADP concentration affects the muscle contraction. From a glycerinated rabbit muscle fiber, myofibriles were prepared by use of a homogenizer until those reached a length of about 100μm. We observed them by using an optical phase contrast microscope (magnification of objective lens, ×40). Contraction was initiated by the contractile solution, including various ADP concentrations (0mM, 2mM, 8mM, 13mM, 20mM). We evaluated the velocity of sarcomere contraction, as a function of ADP or ATP concentration. We report here that ADP behaves as a competitive inhibitior for the myosin ATPase. And we conclude that the step of ADP release plays a role in resistance.
東海大学の論文
2000-03-10