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Unloaded shortening velocity and myosin heavy chain and alkali light chain isoform composition in rat skeletal muscle fibres.
J Physiol. 1994 Jul 15; 478 (Pt 2):341-9.JP

Abstract

1. This study aims to assess the role of myosin heavy chain (MHC) and alkali myosin light chain (MLC) isoforms in determining maximum velocity of shortening in fast skeletal muscle fibres. 2. The maximum velocity of shortening as determined by the slack test (Vo) was tested for its relationship with MHC composition and with alkali MLC isoform ratio of fast fibres of known MHC composition. 3. MHC isoform composition was determined using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and monoclonal antibodies against MHCs, and combining the results obtained using the two methods. Three groups of fast fibres containing only one MHC isoform were identified: IIA, IIX and IIB fibres containing respectively IIA MHC, IIX MHC and IIB MHC. Fibres containing more than one MHC isoform were discarded. 4. The mean Vo value of IIA fibres was 2.33 +/- 0.29 muscle lengths per second (L s-1; mean +/- S.D.), this was significantly lower than that for IIX fibres (3.07 +/- 0.70 L s-1) which in turn had a mean Vo value significantly lower than that for IIB fibres (3.69 +/- 1.01 L s-1). 5. The relative proportion of alkali MLC isoforms (MLC3f, MLC1f) was determined by means of electrophoretic separation and densitometric quantification and was expressed as MLC3f/MLC2f with reference to the dithio-nitrobenzoic acid (DTNB) light chain (MLC2f). The mean value of the MLC3f/MLC2f ratio was significantly lower in IIA than in IIX and IIB fibres. 6. Vo was found to be proportional to the relative content of MLC3f in IIA, IIX and IIB fibres.(

ABSTRACT

TRUNCATED AT 250 WORDS)

Authors+Show Affiliations

Institute of Human Physiology, Pavia, Italy.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

7965849

Citation

Bottinelli, R, et al. "Unloaded Shortening Velocity and Myosin Heavy Chain and Alkali Light Chain Isoform Composition in Rat Skeletal Muscle Fibres." The Journal of Physiology, vol. 478 (Pt 2), 1994, pp. 341-9.
Bottinelli R, Betto R, Schiaffino S, et al. Unloaded shortening velocity and myosin heavy chain and alkali light chain isoform composition in rat skeletal muscle fibres. J Physiol. 1994;478 (Pt 2):341-9.
Bottinelli, R., Betto, R., Schiaffino, S., & Reggiani, C. (1994). Unloaded shortening velocity and myosin heavy chain and alkali light chain isoform composition in rat skeletal muscle fibres. The Journal of Physiology, 478 (Pt 2), 341-9.
Bottinelli R, et al. Unloaded Shortening Velocity and Myosin Heavy Chain and Alkali Light Chain Isoform Composition in Rat Skeletal Muscle Fibres. J Physiol. 1994 Jul 15;478 (Pt 2):341-9. PubMed PMID: 7965849.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Unloaded shortening velocity and myosin heavy chain and alkali light chain isoform composition in rat skeletal muscle fibres. AU - Bottinelli,R, AU - Betto,R, AU - Schiaffino,S, AU - Reggiani,C, PY - 1994/7/15/pubmed PY - 1994/7/15/medline PY - 1994/7/15/entrez SP - 341 EP - 9 JF - The Journal of physiology JO - J Physiol VL - 478 (Pt 2) N2 - 1. This study aims to assess the role of myosin heavy chain (MHC) and alkali myosin light chain (MLC) isoforms in determining maximum velocity of shortening in fast skeletal muscle fibres. 2. The maximum velocity of shortening as determined by the slack test (Vo) was tested for its relationship with MHC composition and with alkali MLC isoform ratio of fast fibres of known MHC composition. 3. MHC isoform composition was determined using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and monoclonal antibodies against MHCs, and combining the results obtained using the two methods. Three groups of fast fibres containing only one MHC isoform were identified: IIA, IIX and IIB fibres containing respectively IIA MHC, IIX MHC and IIB MHC. Fibres containing more than one MHC isoform were discarded. 4. The mean Vo value of IIA fibres was 2.33 +/- 0.29 muscle lengths per second (L s-1; mean +/- S.D.), this was significantly lower than that for IIX fibres (3.07 +/- 0.70 L s-1) which in turn had a mean Vo value significantly lower than that for IIB fibres (3.69 +/- 1.01 L s-1). 5. The relative proportion of alkali MLC isoforms (MLC3f, MLC1f) was determined by means of electrophoretic separation and densitometric quantification and was expressed as MLC3f/MLC2f with reference to the dithio-nitrobenzoic acid (DTNB) light chain (MLC2f). The mean value of the MLC3f/MLC2f ratio was significantly lower in IIA than in IIX and IIB fibres. 6. Vo was found to be proportional to the relative content of MLC3f in IIA, IIX and IIB fibres.(ABSTRACT TRUNCATED AT 250 WORDS) SN - 0022-3751 UR - https://www.unboundmedicine.com/medline/citation/7965849/Unloaded_shortening_velocity_and_myosin_heavy_chain_and_alkali_light_chain_isoform_composition_in_rat_skeletal_muscle_fibres_ L2 - https://onlinelibrary.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=0022-3751&date=1994&volume=478&spage=341 DB - PRIME DP - Unbound Medicine ER -