Nom du corpus

Corpus Systématique Animale

Titre du document

Polymorphic myosin as the common determinant of myofibrillar ATPase in different haemodynamic and thyroid states

Lien vers le document
Springer (journals)
Langue(s) du document
Type de document
Mots-clés d'auteur
  • myosin
  • myofibril
  • ATPase
  • hypertrophy
  • pressure overload
  • training
  • thyroxine
Nom du fichier dans la ressource
  • Dr. H. Rupp
  • Physiologisches Institut, Lehrstuhl II, der Universität Tübingen, Gmelinstraße 5, 7400, Tübingen 1, FRG

Chronic alterations in haemodynamic load or thyroid state affect the ATPase activity of myofibrils from the rat heart. In order to determine the limits of such an adaptational reaction, the Ca2+-dependent activation of myofibrils containing only myosin V1 or V3 was investigated. These limiting states were achieved by changes in the thyroid state, i.e., myosin V1 myofibrils were obtained from 5-week-old rats, and myosin V3 myofibrils from hypothyroid rats. Analysis of the activation of myofibrillar ATPase by Ca2+ using the model-independent Hill equation showed that transition of the myosin isoenzymes neither affected Ca2+ sensitivity (pCa50%=6.52) nor positive co-operativity (n=2.4). The ATPase activity at saturating Ca2+ concentrations was 192 nMole P mg?1 min?1 in myosin V1-myofibrils and was reduced to 131 nMole P mg?1 min?1 in the case of myosin V3-myofibrils. Beside changes in the thyroid hormone state, polymorphic myosin is also influenced by chronic pressure overload and endurance training of a swimming routine. Such haemodynamically induced changes in myofibrillar ATPase were accounted for on the basis of the altered myosin isoenzyme pattern and the ATPase activities of isoenzymatically homogeneous myofibrils obtained by changes in the thyroid state. It can therefore be concluded that both haemodynamic load and thyroid state affect myofibrillar ATPase by a common mechanism, namely, by inducing a change in the isoenzyme pattern of myosin due to a redirected expression of myosin genes. Myosins from other mammals were compared with rat myosin on pyrophosphate gels. The Ca2+-dependent activation of myofibrillar ATPase from euthyroid and hypothyroid adult mice suggested the existence of a polymorphic myosin which was verified by the pyrophosphate gel technique. The mouse myosin isoenzymes were, however, less separated on pyrophosphate gels when compared with the rat myosins. It therefore seems advisable to consider both the activation properties of myofibrillar ATPase, as well as electrophoretic properties, for defining the adaptational state of myocardium of higher mammalian species.

Catégories Science-Metrix
  • 1 - health sciences
  • 2 - clinical medicine
  • 3 - cardiovascular system & hematology
Catégories INIST
  • 1 - sciences appliquees, technologies et medecines
  • 2 - sciences biologiques et medicales
  • 3 - sciences biologiques fondamentales et appliquees. psychologie
Catégories Scopus
  • 1 - Health Sciences ; 2 - Medicine ; 3 - Physiology (medical)
  • 1 - Health Sciences ; 2 - Medicine ; 3 - Cardiology and Cardiovascular Medicine
  • 1 - Life Sciences ; 2 - Biochemistry, Genetics and Molecular Biology ; 3 - Physiology
Catégories WoS
  • 1 - science ; 2 - cardiac & cardiovascular systems
Identifiant ISTEX

Basic Research in Cardiology

Année de publication
Présence de XML structuré
Version PDF
Score qualité du texte
  • Mammiferes
Type de publication
Powered by Lodex 9.3.8