Intracellular sodium in mammalian muscle fibers after eccentric contractions

• Published in: Journal of applied physiology (1985) Vol. 94; no. 6; pp. 2475 - 2482
• Main Authors: Yeung, Ella W, Ballard, Heather J, Bourreau, J.-P, Allen, David G
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Physiological Soc 01.06.2003; American Physiological Society
• Subjects: Animals; Benzofurans; Biological and medical sciences; Cells; Electric Stimulation; Enzyme Inhibitors - pharmacology; Ethers, Cyclic; Fibers; Fluorescent Dyes; Fundamental and applied biological sciences. Psychology; Gadolinium - pharmacology; In Vitro Techniques; Intracellular Membranes - metabolism; Ion Channels - antagonists & inhibitors; Ion Channels - metabolism; Isometric Contraction - drug effects; Isometric Contraction - physiology; Mammals; Mice; Microscopy, Confocal; Muscle Contraction - drug effects; Muscle Contraction - physiology; Muscle Fibers, Skeletal - metabolism; Muscle, Skeletal - physiology; Muscular system; Organic Chemicals; Osmolar Concentration; Ouabain - pharmacology; Rats; Sodium; Sodium - metabolism; Sodium-Potassium-Exchanging ATPase - antagonists & inhibitors; Striated muscle. Tendons; Tissue Distribution; Vertebrates: osteoarticular system, musculoskeletal system; intracellular sodium; eccentric damage; Eccentric; Muscular fiber; Striated muscle; Muscle contraction; stretch-sensitive channels; Vertebrata; Mammalia; Sodium; muscle; Intracellular; gadolinium
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.01128.2002

1  Department of Rehabilitation Sciences, Hong Kong Polytechnic University, Hung Hom, Kowloon; 2  Department of Physiology, University of Hong Kong, Hong Kong, China; and 3  Institute for Biomedical Research and Department of Physiology, University of Sydney F13, Sydney NSW 2006, Australia The effect of eccentric contractions on intracellular Na + concentration ([Na + ] i ) and its distribution were examined in isolated rat and mouse muscle fiber bundles. [Na + ] i was measured with either Na + -binding benzofuran isophthalate or sodium green. Ten isometric contractions had no significant effect on force (measured after 5 min of recovery) and caused no significant change in the resting [Na + ] i (7.2 ± 0.5 mM). In contrast 10 eccentric contractions (40% stretch at 4 muscle lengths/s) reduced developed force at 100   Hz to 45 ± 3% of control and increased [Na + ] i to 16.3 ± 1.6 mM ( n  = 6; P  < 0.001). The rise of [Na + ] i occurred over 1-2 min and showed only minimal recovery after 30 min. Confocal images of the distribution of [Na + ] i showed a spatially uniform distribution both at rest and after eccentric contractions. Gd 3+ (20 µM) had no effect on resting [Na + ] i or control tetanic force but prevented the rise of [Na + ] i and reduced the force deficit after eccentric damage. These data suggest that Na + entry after eccentric contractions may occur principally through stretch-sensitive channels. muscle; eccentric damage; intracellular sodium; gadolinium; stretch-sensitive channels