Alwan, Mohand R.
(2009)
The effect of selenium and tocotrienol supplementation on the muscle contractile properties, fatigue, EMG and antioxidant status of gastrocnemius muscle of trained and untrained rats.
Masters thesis, Universiti Sains Malaysia.
Abstract
Exercise induces radical-mediated oxidative damage of skeletal muscle
membranes which has been implicated in the fatigue process. Selenium (S) is an
important component of cellular selenocompounds and is an integral component of
glutathione Peroxidase (GPx), which catalyze the reduction of harmful peroxides.
Tocotrienol (T) is a major chain breaking antioxidant that has been shown to reduce
contraction mediated oxidative damage. We hypothesized that Sand T supplementation
would positively affect muscle contractile function and increase antioxidant enzymes
activities during exercise. To test this postulate, were used sixty-four male Wistar-Kyoto
rats at weight between 300-350g randomized into eight groups with eight rats per group
rats these sample size was calculated using PS software based on comparing two
means of superoxide dismutase (SOD).
The rats were fed with either S (80 μg/kg body weight) or T (8 mg/kg body
weight) and also with combination of S and T diet in sedentary and jumping exercise
which consisted from 40 jumps for 40 cm in height for 5 days per week for 6 weeks.
Upon completion of the feeding period, animals were anesthetized with an
intraperitoneal injection of sodium pentobarbital ( 40 mg/kg); the sciatic nerve was
located and cut and tendon of the TA muscle was cut close to the bone and attached to
an isometric force transducer (AD Instrument, model 400) with computer-based data
acquisition system (AD Instrument, Power Lab® and Chart software. The muscle contractile properties were measured, fatigue protocol consisted of
trains of pulses composed of fourteen pulses recurring at 40 Hz repeated every 1 s for
at least 2 min in order to assess sensitivity to fatigue. There were significant (P<0.05)
differences in the muscle contractile properties (Pt, Po, Pt/Po Ratio and CT), also
decrease in EMG failure and increase of fatigue index between S, T and control animals
and this difference was still greater in combined supplementation of S and T group of
exercised rats. The stimulated MG muscle from the exercised S and T supplemented
animals had significantly (P<0.05) higher antioxidant enzymes activity in both GPx, CAT
and decreased lipid hydroperoxidation as compared to the same muscles in control
animals as well as in comparison with sedentary supplementation. Most effective results
were observed in combined S and T supplementation animals in exercise group as
compared with sedentary supplementation groups. This data support the hypothesis
that S and T supplementation in exercised animals increases muscular endurance and
improves muscle contractile properties following a prolonged series of contractions.
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