Denervation-induced changes in myosin heavy chain expression in the rat diaphragm muscle

• Published in: Journal of applied physiology (1985) 2003-08, Vol.95 (2), p.611-619
• Main Authors: Geiger, Paige C, Bailey, Jeffrey P, Zhan, Wen-Zhi, Mantilla, Carlos B, Sieck, Gary C
• Format: Article
• Language: English
• Subjects: Air breathing; Animals; Biological and medical sciences; Blotting, Northern; Diaphragm - innervation; Diaphragm - metabolism; Electrophoresis; Electrophoresis, Polyacrylamide Gel; Fundamental and applied biological sciences. Psychology; Male; Muscle Denervation - methods; Muslims; Myosin Heavy Chains - genetics; Myosin Heavy Chains - metabolism; Nervous system; Protein Isoforms - genetics; Protein Isoforms - metabolism; Proteins; Rats; Rats, Sprague-Dawley; Respiratory system: anatomy, metabolism, gas exchange, ventilatory mechanics, respiratory hemodynamics; Ribonucleic acid; RNA; RNA, Messenger - metabolism; Rodents; Vertebrates: respiratory system
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.00862.2002

Departments of 1 Physiology and Biophysics and 2 Anesthesiology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905 Submitted 19 September 2002 ; accepted in final form 26 March 2003 Unilateral denervation (Dnv) of the rat diaphragm muscle (Dia m ) markedly alters expression of myosin heavy chain (MHC) isoforms. After 2 wk of Dia m Dnv, MHC content per half-sarcomere decreases in fibers expressing MHC 2X and MHC 2B . We hypothesized that changes in MHC protein expression parallel changes in MHC mRNA expression. Relative MHC isoform mRNA levels were determined by Northern analysis after 1, 3, 7, and 14 days of Dnv of the rat Dia m . MHC protein expression was determined by SDS-PAGE. Changes in MHC isoform protein and mRNA expression were not concurrent. Expression of MHC Slow and MHC 2X mRNA isoforms decreased dramatically by 3 days of Dnv, whereas that of MHC 2A and MHC 2B did not change. Expression of all MHC protein isoforms decreased by 3 days of Dnv. We observed a differential effect of rat Dia m Dnv on MHC isoform protein and mRNA expression. The time course of the changes in MHC isoform mRNA and protein expression suggests a predominant effect of altered protein turnover rates on MHC protein expression instead of altered transcription after Dnv. innervation patterns; electrophoresis; myosin heavy chain gene regulation; neuromuscular control Address for reprint requests and other correspondence: G. C. Sieck, Dept. of Physiology and Biophysics, Mayo Clinic College of Medicine, 200 First St. SW, Rochester, MN 55905 (E-mail: sieck.gary{at}mayo.edu ).