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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The interstitium of the myocardium is composed of predominantly type I collagen; type III collagen is present to a lesser extent. The fibrillar collagens serve as tethers between muscle cells, muscle fibers, and blood vessels while also providing a scaffolding that supports the muscular and vascular compartments. In pressure overload hypertrophy, a continuous structural remodeling of the fibrillar collagen matrix is seen. What is initially an adaptive process that enhances tensile strength can eventuate in pathologic hypertrophy with muscle fiber entrapment, cell loss, and abnormal diastolic and systolic stiffness of the myocardium. Morphologically distinct patterns of myocardial collagen accumulation, or fibrosis, have been identified based on the alignment of thick and thin collagen fibers to one another and to cardiac muscle. Each pattern, representing either a reactive (without necrosis) or reparative process, can alter stiffness in a unique manner. The manner in which the interstitium regulates the nature and proportion of fibrillar collagen formation is unknown and deserving of further study. Such information may lead to the development of antifibrotic agents that counteract, prevent or modify disproportionate collagen remodeling in pressure overload hypertrophy. These agents may thereby ultimately represent corrective forms of therapy for the management of heart failure.
J Mol Cell Cardiol 1989 Dec
PMID:Patterns of myocardial fibrosis. 253 37

The role of Ca2+ in the initiation and maintenance of contraction has been extensively studies. Many of these studies have focused on how Ca2+ influx and efflux affect cytoplasmic Ca2+ (Cai) and, therefore, contraction in cardiac muscle. However, it has recently become apparent that Cai itself may play a major role in the control of Ca2+ influx and efflux from cardiac muscle. Here we review current ideas on the mechanisms underlying Ca2+ homeostasis in cardiac muscle, with specific attention to how Cai may control Ca2+ influx, both under normal and pathological conditions.
Mol Cell Biochem 1989 Sep 07
PMID:The control of calcium influx by cytoplasmic calcium in mammalian heart muscle. 255 19

Phenazine methosulphate (PMS) or ferricyanide caused ultrastructural damage, including sarcolemma folds and swelling of the sarcoplasmic reticulum (SR), in amphibian skeletal muscle which corresponds with that triggered by a rise in [Ca]i and which, it is suggested, is caused by the activation of NAD(P)H oxidases at the sarcolemma (where it causes sarcolemma folding) and SR (where it causes myofilament damage). PMS also caused SR swelling and more limited damage in chemically-skinned muscle at zero [Ca]. In contrast with the oxygen paradox of cardiac muscle, there is no evidence for the production of oxygen radicals since no protection was provided by N2, mannitol, desferrioxamine or alpha-tocopherol, nor was the cell damage produced by an influx of Ca across the sarcolemma.
Virchows Arch B Cell Pathol Incl Mol Pathol 1989
PMID:Cytotoxicity of phenazine methosulphate on skeletal muscle. The role of the sarcoplasmic reticulum in initiating myofilament damage. 256 22

Incubation of the isolated mouse diaphragm with a high rate of oxygenation (10 ml s-1, 95% O2 + 5% CO2) causes a characteristic cellular damage with widely-separated myofibrils and swollen sarcotubular system within 10 min. This damage was ameliorated by inhibitors of the hydroxyl radical (.OH), desferrioxamine, dimethyl thiourea and 120 mM mannitol, and by incubation at 8 degrees C. It was not prevented either by inhibitors of the pathway leading to sarcolemma damage (nordihydroguaiaretic acid, alpha-tocopherol, butylated hydroxytoluene) nor by agents and treatments that inhibit the oxygen paradox of cardiac muscle (glucose, omission of extracellular calcium, incubation at 30 degrees C, superoxide dismutase and catalase). Nevertheless there are similarities between these two types of damage triggered by O2 and the possibility that in both an NAD(P)H oxidase is stimulated and cytotoxic oxygen radicals are generated is discussed.
Virchows Arch B Cell Pathol Incl Mol Pathol 1989
PMID:Cytotoxic effect of oxygen on the skeletal muscle of mouse diaphragm. 256 50

Experiments were performed to determine the cellular associations of the molecular forms of acetylcholinesterase (AChE) in adult rat heart. For this purpose, a cardiac muscle and a non-muscle fraction were isolated from rat heart ventricles after perfusion with collagenase and hyaluronidase, extracts of these fractions were subjected to ultracentrifugation on linear density gradients of sucrose (5-20%), and fractions of these gradients were analyzed for AChE activity. The results show that only globular AChE molecular forms were present in isolated cardiac muscle cells. Globular AChE forms were also present in the non-muscle cells fraction but in different proportions. The proportions of globular AChE forms plus the high specific activity of choline acetyltransferase in the non-muscle cell fraction suggest that this fraction contains cholinergic nerve fragments. The results of this study also show that asymmetric AChE is released during the perfusion of heart with the digestive enzymes, which suggests that asymmetric AChE is bound to the extracellular matrix of heart.
J Mol Cell Cardiol 1989 Oct
PMID:Acetylcholinesterase molecular forms in muscle and non-muscle cells of rat heart. 258 21

Cardiac myofibrils were isolated from rabbit ventricular muscle by a method that preserves well the integrity of the A-band structure. For the first time electron microscopic observations using the negative staining method revealed, in cardiac A-bands, a full complement of pronounced transverse stripes which indicate the locations of minor proteins in skeletal muscles. The manifestation of some transverse stripes in the cardiac A-band was shown to depend on the duration of muscle incubation in a Ca2(+)-depleting and ATP-free solution before its homogenization into myofibrils. The clear visibility of fine structural details in electron micrographs allowed us to resolve morphological features specific for cardiac muscle at both the central and end parts of the A-bands. The myofibrils demonstrated here are expected to be useful for elucidating the fine structure of cardiac thick filaments and in particular the locations of minor proteins.
J Mol Biol 1989 Dec 05
PMID:Manifestation of the stripes of minor proteins location in A-bands of rabbit cardiac myofibrils. 261 39

The effects of clinical concentrations of halothane (1 and 2% v/v) on detergent treated cardiac fibers were studied in two different models of cardiomyopathic animals, the Syrian hamster UM-X7.1, and the streptozotocin-induced diabetic rat. The changes of contractile properties in cardiac muscle observed on cardiomyopathic animals, although of moderate importance, were different in these two models. The cardiomyopathic hamsters exhibited macroscopic structural changes in cardiac muscle responsible for a significant decrease in maximal activated tension, but myocardial calcium sensitivity was unchanged. On the other hand, in diabetic rats, maximal activated tension was unchanged, while a slight but significant increase in myocardial calcium sensitivity was observed. Addition of halothane produced a similar dose-dependent decrease in myocardial calcium sensitivity, in both the controls and the two groups of cardiomyopathic animals. Halothane exposure was also associated with a dose-dependent decrease in maximal calcium activated tension in all groups, an effect that was more pronounced in cardiomyopathic hamsters than in their control at the lowest anesthetic concentration. These results indicate that the negative inotropic effects of halothane are additive to the myocardial depression observed in these cardiomyopathies.
J Mol Cell Cardiol 1989 Dec
PMID:Effects of halothane on contractile properties of skinned fibers from cardiomyopathic animals. 263 12

Translocation of lipids inside mammalian cells is considered to be facilitated by a number of low-molecular weight lipid binding proteins. An overview of these proteins is given, with particular reference to the heart. Three distinct phospholipid transfer proteins specifically stimulate the net transfer of individual phospholipid classes between membrane structures. In rat cardiac muscle their content is 15-140 pmol/g ww. Fatty acid-binding proteins (FABP) are abundantly present in tissues actively involved in the uptake or utilization of long-chain fatty acids, such as intestine, liver and heart. The four distinct FABP types now identified show a complex tissue distribution with some tissues containing more than one type. Heart (H-) FABP comprises about 5% of the cytosolic protein mass; its content in rat heart is 100 nmol/g ww. Immunochemical evidence has been obtained for the presence of H-FABP in several other tissues, including red skeletal muscle, mammary gland and kidney. Beside long-chain fatty acids FABP binds with similar affinity also fatty acyl-CoA and acyl-L-carnitines. In heart the latter compound may be the primary ligand, since normoxic acyl-L-carnitine levels are several fold higher than those of fatty acids. In addition, H-FABP was found to modulate cardiac energy production by controlling the transfer of acyl-L-carnitine to the mitochondrial beta-oxidative system. H-FABP may also protect the heart against the toxic effects of high intracellular levels of fatty acid intermediates that arise during ischemia.
Mol Cell Biochem
PMID:Intracellular transport of lipids. 267 66

Transport of palmitate from the albumin-palmitate complex in the plasma to inside mitochondria where it undergoes beta-oxidation is a multistep process. Albumin's large size prevents permeation via interendothelial clefts. Palmitate dissociation from albumin in solution is too slow to provide an adequate supply of the unbound palmitate. The discovery that the dissociation occurs upon albumin binding to an endothelial surface receptor resolves the conundrum. Palmitate transport across the luminal surface membrane may be either carrier-mediated or passive. Fatty-acid binding protein inside endothelial and cardiac muscle cells facilitates diffusion through cytosol while maintaining the unbound palmitate concentration at a very low level. Within the interstitium, albumin is again the palmitate carrier. Still controversial is whether or not there is a saturable sarcolemmal transporter or simply passive exchange. Inside the myocyte palmitate is again bound to the fatty acid binding protein which buffers the free palmitate concentration, facilitates diffusion, and may facilitate further intracellular reactions.
Mol Cell Biochem
PMID:Modeling of palmitate transport in the heart. 267 67

Immunochemical studies have shown the presence of a single isoform of troponin T, the adult form, in all chambers of adult chicken and rat hearts. An additional isoform, the embryonic form, was detected during early development of the cardiac muscle. As the amount of adult isoform increased, the embryonic form decreased and was finally suppressed during early post-natal or post-hatch period. The replacement of the embryonic isoform by the adult form appeared slower in the atrium than in the ventricle. While the adult isoform of troponin T was not detected until late in gestation in the rat heart, this isoform of troponin T was present in the chicken heart even at 4 days in ovo.
J Mol Cell Cardiol 1989 Jan
PMID:Identification of and changes in the expression of troponin T isoforms in developing avian and mammalian heart. 271 68


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