The purpose of this study was to determine the effects of longterm differences in workload, in the form of soft and hard diets, on rat masseter muscle function and mass with increasing age. Nineteen male F344 rats were fed a soft diet (SD) from four weeks until the time of sacrifice. Twenty-four male F344 rats were fed a standard hard pellet diet (HD) until the time of sacrifice. Contractile properties of the anterior deep branch of the masseter (ADM) were measured at room temperature (23'C) under isometric conditions using muscles of young (4-6 months), adult (12-13 months) and old (23-24 months) age. Contraction time (CT), half relaxation time (HRT) and endurance (Fi) were significantly less in young SD rats when compared with young HD rats (CT of 37.8 ±1.8 msec versus 48.2 ±1.9 msec, HRT of 41.3 ±3.1 msec versus 60.9 ±5.8 msec and Fi of 0.10 ±0.10 versus 0.21 ± 0.02, SD, n=8, versus HD, n=IO). No significant differences were found in these parameters when adult SD and adult HD rats were compared or when old SD and old HD were compared. However, muscle weight to body weight ratio was significantly less in muscles of adult SD compared to adult HD rats (SD, n=7, versus HD, n=5) and old SD than old HD rats (SD, n=4, versus HD, n=9). Our results indicate that reducing the workload of the ADM muscle over the life span of the F344 rat has no significant impact on contractile characteristics but, is associated with age-related muscle atrophy. NIDR grant:P50DE10756.
|Original language||English (US)|
|State||Published - Dec 1 1996|
ASJC Scopus subject areas
- Molecular Biology