The use of fluorescent dextrans as a marker of sarcolemmal injury.
We investigated the use of intravenously injected fluorescent dextran molecules (FDx) as a histological marker of sarcolemmal injury. Using fluorescent microscopy, uptake of FDx (average MW 10 kD) was assessed in sections of quadriceps muscles from three models: 1) normal (C57BL/10SnJ) mice, 2) normal mice run downhill (0, 3, and 7 days post exercise), and 3) non-exercised mdx (dystrophin-deficient) mice. These were compared to serial sections stained with hematoxylin and eosin (H&E). In control muscles, strong fluorescence was seen between fibers (intercellular). Intracellular FDx was observed within cells of the quadriceps from normal mice run downhill at days 0 and 3 post exercise, but not at day 7. On H&E staining, muscle pathology was not observed until day 3, with regeneration by day 7. Intracellular FDx was also observed within mdx muscles, particularly in fibers that appeared pre-necrotic on H&E stained sections. FDx appears to be useful as a histological marker of changes in sarcolemmal integrity associated with muscle injury from eccentric exercise or muscle disease.
Carter
G T
GT
Department of Physical Medicine and Rehabilitation, School of Medicine, University of California, Davis 95616.
Kikuchi
N
N
Horasek
S J
SJ
Walsh
S A
SA
D000818:Animals; D015415:Biomarkers; D003402:Creatine Kinase / Q000097:blood; D003911:Dextrans; D005069:Evaluation Studies as Topic; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives*; D051379:Mice; D008810:Mice, Inbred C57BL; D018101:Mice, Inbred mdx; D018485:Muscle Fibers, Skeletal / Q000473:pathology*; D010805:Physical Conditioning, Animal; D012508:Sarcolemma / Q000473:pathology*
D015415:Biomarkers; D003911:Dextrans; C015219:fluorescein isothiocyanate dextran; D003402:Creatine Kinase; D016650:Fluorescein-5-isothiocyanate