1994 年 14 巻 2 号 p. 150-157
Changes in the contractile tension and muscle length of rat superficial masseter muscles were measured together with postnatal increases in body weight from the age of 3 to 11 weeks to establish control data during growth. Isolated masseter muscle fiber bundles were used for precise measurement of contractile tension and muscle length. Up to the age of 5 weeks, female rats showed a greater contractile tension than male rats. At the 6th weeks, the level of contractile tension in male and female rats was similar. The tension development curve in 6-to 9-week-old males was sigmoidal, while that in 6-to 8-week-old females showed a linear increase. Male and female rats reached maximum contractile tension at 9 and 8 weeks of age, respectively. The most remarkable changes in contractile tension from the age of 6 to 9 weeks correlated with rapid changes of body both weight and muscle length. Statistically significant relationships were observed between contractile tension and both body weight and muscle length. These findings suggest that the changes in the contractile tension were influenced by morphological changes as well as by individual growth. These findings will also be useful as control data regarding the rat superficial masseter muscle contractile tension.
