Capillary fiber ratio and electrolyte content of compensatory hypertrophied rat soleus

Capillary-to-fiber ratio and the content (mu moles/g muscle) of Na, K, Mg, Ca and Zn was measured in compensatory hypertrophied (CH) soleus muscles of adult Sprague-Dawley rats. The soleus hypertrophy was induced by unilateral tenotomy of the gastrocnemius and the plantaris muscles. Seven days after synergistic tenotomy the compensatory hypertrophied Soleus muscles showed no difference in the capillary-fiber ratio, Sr-extractable calcium ([Ca]Ext.) or the total content of Na, K, Mg and Zn. However, compared to the contralateral control side, the CH muscles showed an increase in the wet muscle weight (31.6%, P less than 0.01) and a significant decline (57.1%, P less than 0.05) in the residual calcium ([Ca]Res.) and 43.2% (P less than 0.05) decrease in the total calcium ([Ca]Total) content. It is concluded that during compensatory hypertrophy of skeletal muscles, the residual Ca reserves are significantly depleted, which may lead to a lower isometric tension generation in the muscle.