Related Experiment Videos
Dihydropyridine effects on skeletal muscle fatigue
1Division of Health and Physical Education, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg 24061-0326.
Abstract:
1. The purpose of this investigation was to determine if alterations in extracellular calcium (Ca2+) influx by the dihydropyridine derivatives Bay K 8644 and nifedipine affected skeletal muscle fatigue. 2. Tetanic contractions (80 Hz, 100 msec) of frog sartorius muscles were evoked every sec for 3 min. Muscles were fatigued in normal Ringer's solution (NR), in NR containing 1 microM nifedipine of 10 microM Bay K 8644 or in low Ca2+ Ringer's. 3. In each case, the experimental conditions increased the rate and magnitude of fatigue. Rate constants of fatigue obtained during Bay K 8644, nifedipine and low Ca2+ conditions (-.0122 +/- .0016, -.0397 +/- 0022 and 0.0169 +/- .0064 sec-1, respectively) were significantly greater than NR (-.0104 +/- .0006 sec-1, p less than .05). In addition, tetanic forces developed at the end of the stimulation period under the experimental conditions (3.90 +/- 0.81, 1.21 +/- 1.40 and 2.04 +/- 1.10% of initial) were significantly less than NR (7.18 +/- 1.27%, p less than .05). 4. Caffeine contracture forces (10 mM) evoked immediately after stimulation were not significantly different between conditions. 5. These results suggest that alterations in sarcolemmal Ca2+ exchange has some influence on the fatigue process.
Insights
Altering calcium (Ca2+) influx with dihydropyridine derivatives significantly increased skeletal muscle fatigue in frog sartorius muscles, suggesting a role for sarcolemmal Ca2+ exchange in muscle fatigue.
Area of Science:
- Physiology
- Muscle Physiology
- Calcium Signaling
Background:
- Skeletal muscle fatigue is a complex physiological process.
- Extracellular calcium influx is crucial for muscle contraction.
- Dihydropyridine derivatives are known modulators of calcium channels.
Purpose of the Study:
- To investigate the effect of altered extracellular calcium (Ca2+) influx on skeletal muscle fatigue.
- To determine if dihydropyridine derivatives (Bay K 8644, nifedipine) influence muscle fatigue rates and magnitudes.
Main Methods:
- Frog sartorius muscles underwent tetanic contractions (80 Hz, 100 msec) every second for 3 minutes.
- Muscles were fatigued in normal Ringer's solution (NR), or NR with nifedipine, Bay K 8644, or low Ca2+.
- Fatigue rate constants and end-stimulation tetanic forces were measured.
Main Results:
- Bay K 8644, nifedipine, and low Ca2+ conditions significantly increased the rate and magnitude of skeletal muscle fatigue compared to NR.
- Fatigue rate constants were significantly greater under experimental conditions (p < .05).
- Tetanic forces at the end of stimulation were significantly reduced under experimental conditions (p < .05).
Conclusions:
- Alterations in sarcolemmal calcium (Ca2+) exchange influence the process of skeletal muscle fatigue.
- Dihydropyridine derivatives and modified extracellular calcium levels can exacerbate muscle fatigue.