Electrophoretic analysis of multiple forms of rat cardiac myosin: Effects of hypophysectomy and thyroxine replacement
01 Nov 1978-Journal of Molecular and Cellular Cardiology (J Mol Cell Cardiol)-Vol. 10, Iss: 11, pp 1053-1076
TL;DR: Electrophoretic analysis in pyrophosphate gels of intact myosin of adult rat myocardium revealed the presence of five distinct components, two in atrialMyosin (A1, A2) and three in ventricular myOSin (V1, V2, V3).
About: This article is published in Journal of Molecular and Cellular Cardiology.The article was published on 1978-11-01. It has received 761 citations till now. The article focuses on the topics: Myosin light-chain kinase & Myosin.
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TL;DR: The existence of the 2X-MHC isoform was confirmed by immunoblotting analysis using muscles containing 2X fibres as a major component, such as the normal and hyperthyroid diaphragm, and the soleus muscle after high frequency chronic stimulation.
Abstract: Mammalian skeletal muscles consist of three main fibre types, type 1, 2A and 2B fibres, with different myosin heavy chain (MHC) composition. We have now identified another fibre type, called type 2X fibre, characterized by a specific MHC isoform. Type 2X fibres, which are widely distributed in rat skeletal muscles, can be distinguished from 2A and 2B fibres by histochemical ATPase activity and by their unique staining pattern with seven anti-MHC monoclonal antibodies. The existence of the 2X-MHC isoform was confirmed by immunoblotting analysis using muscles containing 2X fibres as a major component, such as the normal and hyperthyroid diaphragm, and the soleus muscle after high frequency chronic stimulation. 2X-MHC contains one determinant common to 2B-MHC and another common to all type 2-MHCs, but lacks epitopes specific for 2A- and 2B-MHCs, as well as an epitope present on all other MHCs. By SDS-polyacrylamide gel electrophoresis 2X-MHC shows a lower mobility compared to 2B-MHC and appears to comigrate with 2A-MHC. Muscles containing predominantly 2X-MHC display a velocity of shortening intermediate between that of slow muscles and that of fast muscles composed predominantly of 2B fibres.
948 citations
TL;DR: This review attempts to consider the current state of knowledge of the mechanisms controlling smooth muscle proliferation in these two diseases, to put that knowledge into the context of what is known about smooth muscle biology, and to offer two hypotheses on the possible roles of smooth muscle developmental biology in manifestations of atherosclerosis and hypertension in adult humans.
Abstract: Smooth muscle proliferation has been recognized as central to the pathology of both major forms of vascular disease: atherosclerosis and hypertension. Recent advances in our knowledge of mechanisms of control of proliferation suggest that events occurring in adult animals may recapitulate portions of the developmental biology of the smooth muscle cell. This review attempts to consider the current state of knowledge of the mechanisms controlling smooth muscle proliferation in these two diseases, to put that knowledge into the context of what is known about smooth muscle biology, and to offer two hypotheses on the possible roles of smooth muscle developmental biology in manifestations of atherosclerosis and hypertension in adult humans.
787 citations
Cites background from "Electrophoretic analysis of multipl..."
...Cardiac muscle myosin can be found in three isoenzymatic forms which have been designated VI, V2, and V3 (Hoh et al., 1977)....
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TL;DR: The precise temporal expression of these MHC genes in correlation with the myosin phenotype both during cardiac development and in response to different thyroid hormone levels are established and also document their expression in other muscle tissues.
617 citations
TL;DR: The results demonstrate that all six genes are responsive to thyroid hormone, and the skeletal embryonic and neonatal myosin heavy chain genes, so far considered specific to these two developmental stages, can be reinduced by hypothyroidism in specific adult muscles.
Abstract: In mammals different isoforms of myosin heavy chain are encoded by the members of a multigene family. The expression of each gene of this family is regulated in a tissue- and developmental stage-specific manner as well as by hormonal and various pathological stimuli. In this study the molecular basis of isoform switches induced in myosin heavy chain by thyroid hormone was investigated. The expression of the myosin heavy chain gene family was analyzed in seven different muscles of adult rats subjected to hypo- or hyperthyroidism with complementary DNA probes specific for six different myosin heavy chain genes. The results demonstrate that all six genes are responsive to thyroid hormone. More interestingly, the same myosin heavy chain gene can be regulated by thyroid hormone in highly different modes, even in opposite directions, depending on the tissue in which it is expressed. Furthermore, the skeletal embryonic and neonatal myosin heavy chain genes, so far considered specific to these two developmental stages, can be reinduced by hypothyroidism in specific adult muscles.
611 citations
TL;DR: There is increasing evidence that thyroid hormones have direct chronotropic effect on the heart that are independent of the sympathetic nervous system, and could be mediated in part by sympathetic activation.
Abstract: Cardiovascular manifestations are a frequent finding in hyperthyroid and hypothyroid states. In this review, potential mechanisms by which thyroid hormones may exert their cardiovascular effects and pathophysiological consequences of such effects are briefly discussed. Two major concepts have emerged about how thyroid hormones exert their cardiovascular effects. First, there is increasing evidence that thyroid hormones exert direct effects on the myocardium, which are mediated by stimulation of specific nuclear receptors, which in turn leads to specific mRNAs production. Furthermore, there is some evidence that thyroid hormones may also activate extranuclear sites and may directly alter plasma membrane function. Second, thyroid hormones interact with the sympathetic nervous system by altering responsiveness to sympathetic stimulation presumably by modulating adrenergic receptor function and/or density. Pathophysiological consequences of such direct and indirect thyroid hormone effects include increased myocardial contractility and relaxation that may be related to stimulation by T3 of specific myocardial enzymes. However, when left ventricular hypertrophy occurs in association with hyperthyroidism, it may be related to either direct thyroid hormone-induced stimulation of myocardial protein synthesis or to thyrotoxicosis-induced increases in cardiac work load. Although hyperthyroidism generally has little or no effect on mean arterial blood pressure, hypothyroidism is often associated with increases in diastolic blood pressure that are reversible after hormone substitution and may be mediated in part by sympathetic activation. Moreover, there is increasing evidence that thyroid hormones have direct chronotropic effect on the heart that are independent of the sympathetic nervous system.(ABSTRACT TRUNCATED AT 250 WORDS)
547 citations
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TL;DR: The results show that the polyacrylamide gel electrophoresis method can be used with great confidence to determine the molecular weights of polypeptide chains for a wide variety of proteins.
19,381 citations
TL;DR: A role for the ATPase activity of myosin in determining the speed of muscle contraction is suggested and the F-actin-binding ability of myOSin from various muscles was rather constant.
Abstract: Myosin was isolated from 14 different muscles (mammals, lower vertebrates, and invertebrates) of known maximal speed of shortening. These myosin preparations were homogeneous in the analytical ultracentrifuge or, in a few cases, showed, in addition to the main myosin peak, part of the myosin in aggregated form. Actin- and Ca++-activated ATPase activities of the myosins were generally proportional to the speed of shortening of their respective muscles; i.e. the greater the intrinsic speed, the higher the ATPase activity. This relation was found when the speed of shortening ranged from 0.1 to 24 muscle lengths/sec. The temperature coefficient of the Ca++-activated myosin ATPase was the same as that of the speed of shortening, Q10 about 2. Higher Q10 values were found for the actin-activated myosin ATPase, especially below 10°C. By using myofibrils instead of reconstituted actomyosin, Q10 values close to 2 could be obtained for the Mg++-activated myofibrillar ATPase at ionic strength of 0.014. In another series of experiments, myosin was isolated from 11 different muscles of known isometric twitch contraction time. The ATPase activity of these myosins was inversely proportional to the contraction time of the muscles. These results suggest a role for the ATPase activity of myosin in determining the speed of muscle contraction. In contrast to the ATPase activity of myosin, which varied according to the speed of contraction, the F-actin-binding ability of myosin from various muscles was rather constant.
1,944 citations
TL;DR: The author examines the relationship between ATPase activity of myosin and intrinsic speed of shortening, and the effects of nerve cross-union on properties of myOSin.
Abstract: Introduction. ............................................................ 129 Fiber Types. ............................................................ 130 Historical introduction. ................................................. 130 Classification and terminology. ........................................... 131 Contractile properties of different types of fiber. ............................ 134 Mechanical Properties. .................................................... 138 Introduction ........................................................... 138 Series-elastic component. ................................................ 138 Length : tension relation of contractile material. ............................. 140 Force: velocity properties of contractile component. ......................... 145 Behavior of series-elastic and contractile components in isotonic and isometric contractions ....................................................... 147 Active state, time course of isometric twitch, and posttetanic potentiation ....... 149 Ontogenetic Differentiation of Fast and Slow Muscles. ......................... 161 Growth ............................................................... 161 Dynamic properties. .................................................... 163 Other developmental changes. .......................................... 166 Kelation Between Size and Speed of Contraction .............................. 166 Speed of contraction of homologous muscles of different species. ............. 166 Speed of contraction of different muscles of same animal. .................... 169 Neural Control of Dynamic Properties. ...................................... 170 Introductiorl ........................................................... 170 Dynamic properties of normal and cross-innervated muscles .................. 172 Effects of nerve cross-union on properties of myosin. ......................... 175 Neural influences on noncontractile structures in muscle cells ................. 176 Correlations Between Dynamic and Chemical Properties of Contractile Material. .. 177 Introduction ........................................................... 177 Structure of myosin. .................................................... 177 Relation between ATPase activity of myosin and intrinsic speed of shortening . 181 Functional differences between fast and slow muscles. ....................... 182 Review of Some Major Problems ........................................... 183
1,865 citations
889 citations
TL;DR: Relative mobility values for macromolecules in polyacrylamide gel electrophoresis at various gel concentrations are used to compute the retardation coefficient, KR, molecular radius, R, free mobility, M0, and valence, V.
690 citations