Age-related change in activation by Tris (hydroxymethyl) aminomethane on myosin-ATPase activity of human minor pectoral muscles. 
Age related change of the human minor pectoral muscles was biochemically demonstrated.  Myosin-ATPase activity was significantly decreased with age, and was activated with Tris.  The degree of the activation by Tris was observed to be lower in old aged patients than in the young.  Furthermore, at low concentration of CaCl2 (less than 100 microM), myosin-ATPase activity was higher in the young age than in the old, while at high concentration of CaCl2 (more than 1 mM) no significant difference was observed between young and old age.  Decrease with age in activation by primary amine such as Tris would play an important role in the muscle working capacity in old age.