Author/Editor		Stirn-Kranjc, Branka; Sketelj, Janez; Albis, Anne D; Ambrož, Marko; Eržen, Ida
Title		Fibre types and myosin heavy chain expression in the ocular medial rectus muscle of the adult rat
Type		članek
Source		J Muscle Res Cell Motil
Vol. and No.		Letnik 21, št. 8
Publication year		2000
Volume		str. 753-61
Language		eng
Abstract		Myosin heavy chain (MHC) expression was determined immunohistochemically in individual muscle fibre types characterised by activities of ATPase and the key oxidative and glycolytic enzymes in rat ocular medial rectus (MR) muscles. In the global layer (GL), glycolytic activity of muscle fibres was higher and oxidative activity lower, than in the orbital layer (OL). Muscle fibres in the former displayed rosette-like organisation with a slow fibre surrounded by several fast fibres, which expressed either MHCIIa or MHCIIb, but many co-expressed both isoforms. In the OL some slow fibres co-expressed MHCIIa. Extraocular MHC isoform (MHCeom) could not be determined immunohistochemically and no pure MHCIIx/d containing fibres were found, suggesting that these isoforms, demonstrated electrophoretically, are co-expressed with others. Slow muscle fibres in both layers co-expressed MHCbeta slow, MHCalpha cardiac and MHC-slow tonic. Neonatal isoform (MHCneo) was co-expressed in several fast and slow muscle fibres in the orbital, but not global layer. Slow fibres in the GL displayed very low oxidative activity. Electrophoretic analysis of ocular MR muscle homogenates revealed that about 50% of total MHC was MHCIIb, MHCeom was quite prominent (25%), and MHCIIa, MHCIIx/d and MHCI contributed each about 8%. MHCneo, MHCslow tonic and MHCalpha cardiac could not be identified as separate bands.
Descriptors		OCULOMOTOR MUSCLES MYOSIN HEAVY CHAINS MUSCLE FIBERS RATS, WISTAR IMMUNOHISTOCHEMISTRY ADENOSINE TRIPHOSPHATE