Differences in muscle fiber growth in slow-twitch muscles of the forelimb and hindlimb of the rat: role of the pituitary and food intake.

This investigation tested the hypothesis that differences in the growth of fore- and hindlimb muscles in the rat are regulated by the pituitary and food intake. Using morphometric techniques, the growth of muscle fibers was compared in two slow-twitch muscles, the flexor carpi ulnaris (FCU) of the forelimb, and the soleus of the hindlimb, in male Wistar rats fed ad libitum, food restricted (FR) or hypophysectomized (hypox) from age 60 days. Growth was defined as an increase in fiber diameter and/or type 1 fiber percentage.