title: Regional specialization of rat quadriceps myosin heavy chain isoforms occurring in distal to proximal parts of middle and deep regions is not mirrored by citrate synthase activity.
abstract: Myosin heavy chain (MHC) isoform content and citrate synthase (CS) activities were measured in the Quadriceps femoris (QF) muscle of 18 female rats. The muscle group was divided into superficial, middle and deep, distal, central and proximal parts. MHC IIb and IIx were more abundant in superficial regions (P<0.05) with low CS activities compared with deeper parts. The deeper parts expressed all four isoforms (MHC IIb, MHC IIx, MHC IIa and MHC I), with a concomitantly higher CS activity. MHC I, MHC IIa and MHC IIb isoform content varied significantly along the length of the deep regions. Only MHC IIb and CS activity in the proximal middle part correlated (negatively) with each other. This study showed that the QF has regional specialization and that standardization of sampling site is important. Furthermore, CS activity and MHC isoforms are only loosely associated, or not at all.
authors.affiliation: Department of Physiological Sciences, University of Stellenbosch, South Africa.
authors.forename: Tertius Abraham
authors.initials: TA
authors.lastname: Kohn
authors.forename: Kathryn Helen
authors.initials: KH
authors.lastname: Myburgh
mesh_terms: D000818:Animals; D002950:Citrate (si)-Synthase / Q000032:analysis*; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D018995:Myosin Heavy Chains / Q000032:analysis* / Q000378:metabolism; D020033:Protein Isoforms / Q000032:analysis* / Q000378:metabolism; D052097:Quadriceps Muscle / Q000033:anatomy & histology / Q000737:chemistry* / Q000201:enzymology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013053:Spectrophotometry
chemical_list: D020033:Protein Isoforms; D002950:Citrate (si)-Synthase; D018995:Myosin Heavy Chains