Effect of high-fat diet on sarcoplasmic reticulum Ca(++)-ATPase activity in different types of rat skeletal muscle.

The aim of the present study was to examine the effect of a high-fat diet on the Ca(2+)-ATPase activity in the sarcoplasmic reticulum of the flexor digitorum longus (fast-twitch, glycolytic muscle) and the soleus (slow-twitch, oxidative muscle). The enzyme activity in the extensor digitorum longus was several-fold higher than in the soleus. The high-fat diet increased the enzyme activity by 22% (p < 0.05) in the soleus but it had no effect in the flexor digitorum longus. It is concluded that a high-fat diet increases the activity of only one isoform of the enzyme, namely the one which is present in the slow-twitch oxidative fibers.