Distribution of cardiac myosin isozymes in human conduction system. Immunohistochemical study using monoclonal antibodies.

Kuro‐o, Makoto; Tsuchimochi, Hidetsugu; Ueda, Seigo; Takaku, Fumimaro; Yazaki, Yoshio

doi:10.1172/jci112310

Cited by 48 publications

(21 citation statements)

References 25 publications

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“…The heterogeneity of myosin in the human heart has already been evidenced either with mono-or polyclonal antibodies (11,16,19,32). Each isoform has been related to a and 13 isoforms according to Hoh (13).…”

Section: Discussionmentioning

confidence: 99%

Distribution pattern of α and β myosin in normal and diseased human ventricular myocardium

Bouvagnet

Mairhofer²,

Leger

et al. 1989

Basic Res Cardiol

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All fibers in three normal, four dilated, and two ischemic human ventricles were classified according to their myosin content using three sets of monoclonal antibodies each specific for one myosin heavy chain isoform (alpha, beta and beta'). Numerous fibers contained only beta myosin heavy chain (denoted as beta fibers), others contained either alpha and beta, or beta and beta' myosin heavy chain (denoted as alpha beta and beta beta' fibers, respectively). The percentages of alpha beta fibers were systematically determined along the walls of seven homologous regions of the ventricular myocardium. In all ventricles, there was an alpha beta-fiber transmural gradient, with less alpha beta fiber in the subendocardium than in the subepicardium. More alpha beta fibers were found in the right than in the left ventricular wall but there was no difference between the mid-portion and the apex of the free wall of each ventricle. The diseased ventricles contained a lower alpha beta fiber percentage than the normal hearts. beta beta' fibers were very rare in the normal ventricles (less than 5%) and almost inexistent in pathological hearts. The correlation between the mean alpha beta fiber percentages of the diseased hearts and their cardiac indices (r = 0.88, P less than 0.05) suggests that the small amount of alpha myosin distributed in a large number of ventricular fibers could play a role in the contractile performance of the heart. In conclusion, this study provides evidence for 1) an alpha beta fiber transmural gradient, and 2) a lower alpha myosin ratio in diseased than in normal human ventricle.

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Section: Discussionmentioning

confidence: 99%

Distribution pattern of α and β myosin in normal and diseased human ventricular myocardium

Bouvagnet

Mairhofer²,

Leger

et al. 1989

Basic Res Cardiol

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show abstract

“…Also, the atrioventricular nodal cells coexpress both myosin isoforms in chickens, 47,85 cows, 86 and humans. 84,87 In the developing AVN of rats 82 and mice (authors' unpublished data, 1997), however, no expression of ␤-MHC was found, which may be a characteristic of small animals or merely reflect phylogenetic interspecies variation.…”

Section: Contractile Proteinsmentioning

confidence: 99%

“…Subsequently, this was also noticed in mammalian species, including rats, 157 rabbits, 158 cows, 86,158 and humans. 87 Initially, both isoforms are expressed in opposite gradients and only gradually become confined to either the atrium or ventricle. 6,11,47,81,159 Coexpression persists a relatively long time in the slow-conducting flanking segments (IFT, AVC, and OFT) but also in the fast-conducting TVC.…”

Section: Contractile Proteinsmentioning

confidence: 99%

Development of the Cardiac Conduction System

Moorman

Jong

Denyn

et al. 1998

Circulation Research

233

184

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“…In conditions of heart failure, there is a significant upregulation of the slower ␤-MHC isoform and a downregulation of the faster ␣-MHC isoform in rodents (15,20,35), and in human chronic heart failure, the expression of ␣-MHC is virtually absent (37,38,40,42,49). Furthermore, since the expression of ␣-MHC in mammalian hearts is more abundant in the LV epicardium than in the endocardium (6,7,12,33,48,49,62), shifts in the expression of ␣-MHC can have significant effects on the regional timing and strength of contractile function in the heart. An indepth understanding of the effects of contractile protein composition on myocardial function requires the characterization of regional myocardial wall motion in vivo.…”

mentioning

confidence: 99%

Altered in vivo left ventricular torsion and principal strains in hypothyroid rats

Chen

Somji²,

Yu³

et al. 2010

American Journal of Physiology-Heart and Circulatory Physiology

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Altered in vivo left ventricular torsion and principal strains in hypothyroid rats. Am J Physiol Heart Circ Physiol 299: H1577-H1587, 2010. First published August 20, 2010 doi:10.1152/ajpheart.00406.2010.-The twisting and untwisting motions of the left ventricle (LV) lead to efficient ejection of blood during systole and filling of the ventricle during diastole. Global LV mechanical performance is dependent on the contractile properties of cardiac myocytes; however, it is not known how changes in contractile protein expression affect the pattern and timing of LV rotation. At the myofilament level, contractile performance is largely dependent on the isoforms of myosin heavy chain (MHC) that are expressed. Therefore, in this study, we used MRI to examine the in vivo mechanical consequences of altered MHC isoform expression by comparing the contractile properties of hypothyroid rats, which expressed only the slow ␤-MHC isoform, and euthyroid rats, which predominantly expressed the fast ␣-MHC isoform. Unloaded shortening velocity (Vo) and apparent rate constants of force development (ktr) were measured in the skinned ventricular myocardium isolated from euthyroid and hypothyroid hearts. Increased expression of ␤-MHC reduced LV torsion and fiber strain and delayed the development of peak torsion and strain during systole. Depressed in vivo mechanical performance in hypothyroid rats was related to slowed cross-bridge performance, as indicated by significantly slower Vo and ktr, compared with euthyroid rats. Dobutamine infusion in hypothyroid hearts produced smaller increases in torsion and strain and aberrant transmural torsion patterns, suggesting that the myocardial response to ␤-adrenergic stress is compromised. Thus, increased expression of ␤-MHC alters the pattern and decreases the magnitude of LV rotation, contributing to reduced mechanical performance during systole, especially in conditions of increased workload. magnetic resonance imaging; myosin heavy chain; myocardial contractility; dobutamine; cardiac muscle contraction DURING THE EARLY PHASE of isovolumic contraction, the ventricular apex and base initially rotate in a counterclockwise direction when viewed from the apex to base (55), and later in systole, the base rotates in a clockwise direction, whereas the apex continues to rotate in a counterclockwise direction (36). Toward the end of systole and early diastole, the direction of torsion is reversed as the ventricle untwists (51, 56). The systolic twisting and diastolic untwisting of the left ventricle (LV) optimize the ejection of blood and the filling of the chamber during systole and diastole, respectively. The pattern of ventricular rotation during systole and diastole is facilitated by the architectural design of the LV, in which the subendocardial fibers are oriented in a right-handed helix and the epicardial fibers in an opposing left-handed helix (64), creating the torsion associated with the wringing and unwringing motions of the heart. The sequence of electromechanical activation occurs in ...

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Distribution of cardiac myosin isozymes in human conduction system. Immunohistochemical study using monoclonal antibodies.

Cited by 48 publications

References 25 publications

Distribution pattern of α and β myosin in normal and diseased human ventricular myocardium

Distribution pattern of α and β myosin in normal and diseased human ventricular myocardium

Development of the Cardiac Conduction System

Altered in vivo left ventricular torsion and principal strains in hypothyroid rats

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