Abstract
Background: Astaxanthin (AX) a marine carotenoid is a powerful natural antioxidant which protects against oxidative stress and improves muscle performance. Retinol and its derivatives were described to affect lipid and energy metabolism. Up to date, the effects of AX and retinol on excitation-contraction coupling (ECC) in skeletal muscle are poorly described. Methods: 18 C57Bl6 mice were divided into two groups: Control and AX supplemented in rodent chow for 4 weeks (AstaReal A1010). In vivo and in vitro force and intracellular calcium homeostasis was studied. In some experiments acute treatment with retinol was employed. Results: The voltage activation of calcium transients (V50) were investigated in single flexor digitorum brevis isolated fibers under patch clamp and no significant changes were found following AX supplementation. Retinol shifted V50 towards more positive values and decreased the peak F/F0 of the calcium transients. The amplitude of tetani in the extensor digitorum longus was significantly higher in AX than in control group. Lastly, the mitochondrial calcium uptake was found to be less prominent in AX. Conclusion: AX supplementation increases in vitro tetanic force without affecting ECC and exerts a protecting effect on the mitochondria. Retinol treatment has an inhibitory effect on ECC in skeletal muscle.
Highlights
The energy required for muscle contraction arises from the breakdown of ATP
We examined the effect of retinol—a structurally similar compound to AX—on the excitation-contraction coupling (ECC) mechanism and fatigability of fast twitch skeletal muscles and propose a model of AX actions
Diego, Since AX was proposed as a potent antioxidant affecting cell metabolism, the chronic effect of AX administration on body weight was evaluated
Summary
The mitochondria being the site of most ATP production play a critical role in skeletal muscle function [1]. The aerobic production of ATP highly depends on the morphological and functional state of mitochondria, including appropriate intra-mitochondrial calcium levels. Under physiological conditions the production of ROS, which are crucial in signaling processes, and the activity of the antioxidant systems are strictly balanced. The latter is responsible for the removal of ROS and comprised of exogenous and endogenous antioxidant molecules and enzymes as catalase, superoxide dismutase (SOD), lacto-peroxidases, and glutathione peroxidase. The effects of AX and retinol on excitation-contraction coupling (ECC) in skeletal muscle are poorly described. The amplitude of tetani in the extensor digitorum longus was significantly higher in AX than in control group
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