Total concentration of zinc or calcium was determined in acid digests of rat soleus or plantaris muscle tissue by ICP-MS. Results are expressed in mmole/kg (muscle wet weight). *, significantly different when Zn²⁺ is compared with Ca²⁺ in the soleus muscle; P < 0.05; Student’s unpaired t test. ***, significantly different when Zn²⁺ is compared with Ca²⁺ in the plantaris muscle, and when Zn²⁺ in the soleus is compared with Zn²⁺ in the plantaris; P < 0.0001; Student’s unpaired t test. No significant difference was found when comparing Ca²⁺ in the soleus with Ca²⁺ in the plantaris muscle. n = 5 for each muscle type. Error bars represent mean ± SEM.