Histochemical study on end-plate cholinesterase in aged mice

The cholinesterase activity at the motor end-plate of aged mice was investigated histochemically. A relative quantitative method was applied for studying the reaction at end-plates by utilizing varying concentrations of eserine. The number of end-plates reacting at a concentration of more than 5 X 10(-6) M eserine was reduced in aged diaphragm but increased in aged soleus muscle at 10(-5) M eserine in comparison with those in the young. It seems likely that there is an age-related change in cholinesterase activities in relation to muscle fiber types.