Changes in the water and electrolyte content of skeletal muscles of the mouse during post-natal development

Abstract

1. 1. A study was made of the changes in total water, sodium, chloride and potassium in the biceps brachii (BB), extensor digitorum longus (EDL) and soleus (SOL) muscles of the mouse durinf post-natal development. 2. 2. There was a decrease in the total water, sodium and chloride content in all three muscles. 3. 3. Potassium expressed per unit wet wt. increased in the BB and EDL during development, but in the SOL it increased and then decreased. On a dry tissues basis there was a decrease in potassium in all three muscles, the change was greatest in the SOL. 4. 4. There were significant differences between the three muscles in their electrolytes content at maturity. In the SOL potassium was less and sodium and chloride greater than in the BB and EDL. 5. 5. Differences were noted between the muscles in their time to reach maturity. The SOL took up to 12 weeks, while the BB took only 6 weeks.