THE ULTRASTRUCTURE OF THE CAT MYOCARDIUM: I. Ventricular Papillary Muscle
Don W. Fawcett,N. Scott McNutt +1 more
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In papillary muscles worked in vitro without added substrate, there is a marked depletion of both glycogen and lipid, and no morphological evidence for preferential use of glycogen was found.Abstract:
The ultrastructure of cat papillary muscle was studied with respect to the organization of the contractile material, the structure of the organelles, and the cell junctions. The morphological changes during prolonged work in vitro and some effects of fixation were assessed. The myofilaments are associated in a single coherent bundle extending throughout the fiber cross-section. The absence of discrete "myofibrils" in well preserved cardiac muscle is emphasized. The abundant mitochondria confined in clefts among the myofilaments often have slender prolongations, possibly related to changes in their number or their distribution as energy sources within the contractile mass. The large T tubules that penetrate ventricular cardiac muscle fibers at successive I bands are arranged in rows and are lined with a layer of protein-polysaccharide. Longitudinal connections between T tubules are common. The simple plexiform sarcoplasmic reticulum is continuous across the Z lines, and no circumferential "Z tubules" were identified. Specialized contacts between the reticulum and the sarcolemma are established on the T tubules and the cell periphery via subsarcolemmal saccules or cisterns. At cell junctions, a 20 A gap can be demonstrated between the apposed membranes in those areas commonly interpreted as sites of membrane fusion. In papillary muscles worked in vitro without added substrate, there is a marked depletion of both glycogen and lipid. No morphological evidence for preferential use of glycogen was found.read more
Citations
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Structure and function of intercellular junctions.
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Junctophilins: a novel family of junctional membrane complex proteins.
Hiroshi Takeshima,Hiroshi Takeshima,Shinji Komazaki,Miyuki Nishi,Miyuki Nishi,Masamitsu Iino,Kenji Kangawa +6 more
TL;DR: The junctophilins (JPs), a novel conserved family of proteins that are components of the junctional complexes, are identified and suggest that JPs are important components of junctional membrane complexes.
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Models of cardiac tissue electrophysiology: progress, challenges and open questions.
Richard H. Clayton,Olivier Bernus,Elizabeth M. Cherry,Hans Dierckx,Flavio H. Fenton,L Mirabella,L Mirabella,Alexander V. Panfilov,Frank B. Sachse,Gunnar Seemann,Henggui Zhang +10 more
TL;DR: This paper proposes a tentative list of information that could be included in published descriptions of tissue electrophysiology models, and used to support interpretation and evaluation of simulation results, to discuss challenges and open questions.
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Antisera directed against connexin43 peptides react with a 43-kD protein localized to gap junctions in myocardium and other tissues.
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Sarcoplasmic reticulum and excitation-contraction coupling in mammalian smooth muscles
TL;DR: The presence of both thick and thin myofilaments and of rough SR in smooth muscles supports the dual, contractile and morphogenetic, function of smooth muscle.
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