Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.3.1 (Mg2+-ATPase)
 1,484 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Chronic low-frequency stimulation of rabbit tibialis anterior muscle over a 24-h period induces a conspicuous loss of isometric tension that is unrelated to muscle energy metabolism (J.A. Cadefau, J. Parra, R. Cusso, G. Heine, D. Pette, Responses of fatigable and fatigue-resistant fibres of rabbit muscle to low-frequency stimulation, Pflugers Arch. 424 (1993) 529-537). To assess the involvement of sarcoplasmic reticulum and transverse tubular system in this force impairment, we isolated microsomal fractions from stimulated and control (contralateral, unstimulated) muscles on discontinuous sucrose gradients (27-32-34-38-45%, wt/wt). All the fractions were characterized in terms of calcium content, Ca2+/Mg2+-ATPase activity, and radioligand binding of [3H]-PN 200-110 and [3H]ryanodine, specific to dihydropyridine-sensitive calcium channels and ryanodine receptors, respectively. Gradient fractions of muscles stimulated for 24 h underwent acute changes in the pattern of protein bands. First, light fractions from longitudinal sarcoplasmic reticulum, enriched in Ca2+-ATPase activity, R1 and R2, were greatly reduced (67% and 51%, respectively); this reduction was reflected in protein yield of crude microsomal fractions prior to gradient loading (25%). Second, heavy fractions from the sarcoplasmic reticulum were modified, and part (52%) of the R3 fraction was shifted to the R4 fraction, which appeared as a thick, clotted band. Quantification of [3H]-PN 200-110 and [3H]-ryanodine binding revealed co-migration of terminal cisternae and t-tubules from R3 to R4, indicating the presence of triads. This density change may be associated with calcium overload of the sarcoplasmic reticulum, since total calcium rose three- to fourfold in stimulated muscle homogenates. These changes correlate well with ultrastructural damage to longitudinal sarcoplasmic reticulum and swelling of t-tubules revealed by electron microscopy. The ultrastructural changes observed here reflect exercise-induced damage of membrane systems that might severely compromise muscle function. Since this process is reversible, we suggest that it may be part of a physiological response to fatigue.
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PMID:Disturbances of the sarcoplasmic reticulum and transverse tubular system in 24-h electrostimulated fast-twitch skeletal muscle. 1567 Jul 32

American ginseng (Panax quinquefolium L.) was reported to have extensive biological activities and pharmaceutical properties. In most of the studies, the anti-fatigue effects of American ginseng are attributed to ginsenoside, and in only a few studies, they have been attributed to oligopeptides. Therefore, the aim of this study was to observe the anti-fatigue effects of small-molecule oligopeptides isolated from Panax quinquefolium L. (QOPs) in mice. At first, mice chosen for the study were randomly divided into four experimental groups; each group of mice was further divided into five subgroups: vehicle control group, whey protein group (450 mg per kg BW), and three groups of QOPs at different doses (225 mg per kg BW, 450 mg per kg BW, and 900 mg per kg BW). Test substances were given by gavage once a day for 30 days. QOPs can significantly prolong the forced swimming time, decrease the serum urea nitrogen (SUN) and blood lactate (BLA) levels, and increase the lactate dehydrogenase (LDH) activity and hepatic glycogen content. QOPs also markedly enhanced the superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity and attenuated the malondialdehyde (MDA) levels. Notably, QOPs enhanced the activity of succinate dehydrogenase (SDH), Na+-K+-ATPase, and Ca2+-Mg2+-ATPase and increased the mRNA expression of nuclear respiratory factor 1 (NRF-1) and mitochondrial transcription factor A (TFAM) and the mitochondrial DNA (mtDNA) content in skeletal muscles. These results indicate that treatment with QOPs induces anti-fatigue effects, which may be due to the inhibition of oxidative stress and the improvement of mitochondrial function in skeletal muscles. QOPs can be used as a novel natural agent for relieving physical fatigue.
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PMID:Anti-fatigue effects of small-molecule oligopeptides isolated from Panax quinquefolium L. in mice. 3002 91