Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Eight 6-week-old piglets were inoculated with a strain of encephalomyocarditis virus (EMCV) isolated from an outbreak which occurred naturally in the Po Valley in 1988. Two non-infected animals, kept in the same cage, were used as controls. Out of the eight inoculated piglets, two died and two were suppressed on the 2nd post infection day (PID), the four remaining were killed on the 5th, 7th, 11th and 15th PIDs. Control animals were killed at the end of the experiment. The pathogenesis of myocarditis has been studied using routine methods (Alcian-PAS, Masson's trichrome, Gomori's for reticulin and Mallory's stain), histochemical techniques (ATPase and NADH-TR reactions) and ultrastructural observations (TEM). All the inoculated piglets showed macro and/or microscopic lesions of lymphocytic myocarditis, only in one case associated with fibrinous exudation. One control piglet also showed myocarditic lesions, probably due to a contact infection. An early myocardial fibrosis was already present on the 5th PID. Ultrastructurally the cardiac muscle cells showed severe myofibrillar losses and other regressive alterations. Only on the 15th PID did we observe calcification of the degenerating myocytes, while ultrastructurally we detected needle-like calcium deposits in the mitochondria from the 5th PID. From the 5th PID in the areas of myocarditis the myocytes showed a reduction and/or absence of ATPase and NADH-TR reactions. On TEM, one or more aggregates of viral particles in crystalline array were detected in the cytoplasm of many endothelial cells.
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PMID:Ultrastructural study of experimental myocarditis induced by cardiovirus (EMCV-M) in swine. 132 99

Using a sensitive potentiometric method the effect of isoproterenol upon the activity of Na, K-ATPase in cardiomyocytes has been studied. The activity of the enzyme in rat sarcolemma at isoproterenol-induced myocarditis decreases by 42%. A direct action of isoproterenol on the Na, K-ATPase activity in sarcolemma in vitro has been investigated. In the concentration range 10(-9)-10(-3) M (from receptor-binding up to cardiotoxic) a gradual decrease of the activity reaching the complete inhibition at 10(-3) M is revealed. Antagonist of beta-adrenoreceptors propranolol in concentrations required for displacing the agonist (10(-9) M) provides for the recovery of the Na, K-ATPase activity up to 76% of its normal activity. This action transforms into nonspecific inhibition at rising concentration of the antagonist. Possible mechanisms of the beta-adrenergic regulation effect in cardiomyocytes on Na, K-ATPase of the sarcolemma are discussed.
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PMID:[The beta-adrenergic regulation of the Na, K-ATPase activity in the sarcolemma of the heart muscle]. 216 11

In rats with adrenaline-induced myocarditis conditionally therapeutic doses of strophanthin (2.7 mg/kg) and digoxin (0.89 mg/kg) were chosen according to performance of the test of swimming until the complete fatigue. The influence of drugs in these doses on enzymatic activity was evaluated by histochemical methods in heart of control and myocarditis rats. It was found out that both of cardiac glycosides decreased lactate dehydrogenase and membrane Na+, K+-ATPase activity and increased succinate dehydrogenase activity in rats with experimental myocarditis.
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PMID:[Effect of strophanthin and digoxin on the activity of succinate and lactate dehydrogenases and membrane Na+, K+-ATPase in the heart of rats with experimental myocarditis]. 254 33

This paper demonstrates that antibodies against neurotransmitter receptors of the cardiac membrane are able to alter the physiology, pharmacology and biochemistry of the target organ. Sera from chagasic patients contain an antibody which binds to beta adrenoceptors of myocardium and modulates their activity. Chagasic IgG simulates a partial beta agonist by increasing contractility and diminishing reactivity to exogenous norepinephrine. Moreover, chagasic IgG inhibits the binding of the specific radioligand to purified cardiac membranes. The interaction of chagasic IgG with beta-adrenoceptors triggers signal transduction resulting in the stimulation of adenylate cyclase with an increased production of cAMP. Stimulation of Ca(++)-ATPase and inhibition of Na+ + K(+)-ATPase are also observed. These enzyme dysfunctions induce modifications of cellular thermodynamic equilibrium that trigger both morphological and functional alterations of the myocardium. Other immune sera can also trigger pharmacologic effects on isolated atria. Immune IgG directed against specific alloantigens and IgG from mice with autoimmune myocarditis are able to recognize the beta adrenergic receptor-coupled adenylate cyclase system and alter the function of target organs. The detection of antibodies against neurotransmitter receptors could be a useful marker during the early stages of development of autoimmune diseases.
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PMID:[Interaction of antibodies with cardiac neurotransmitter receptors]. 256 95

The viscosity of membranes isolated from sarcoplasmic reticulum of rabbits with isadrine myocarditis was studied, using pyrene as a hydrophobic fluorescent probe. The increase in the viscosity of membranes from injured heart occurred at lower temperatures and was sharper than in the case of intact heart in both "free" and "bound" lipid domains. The increase in the lipid viscosity under myocarditis was associated with decreased Ca++, Mg++ -ATPase and cAMP-dependent protein kinase activities and with an elevated content of lipid peroxidation products.
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PMID:The increase in viscosity and peroxidation of sarcoplasmic reticulum membrane lipids in isadrine myocarditis. 296 98

The fluorescent hydrophobic pyrene probe was employed to study the viscosity of membrane lipids of rat heart sarcoplasmic reticulum in isoproterenol myocarditis. During pyrene incorporation into the reticulum obtained from the affected myocardium, the increase in the microviscosity occurred at lower temperatures and more rapidly both in "bound" and "free" membrane lipids as compared with normal. The increase of the viscosity of the reticulum membranes in isoproterenol myocarditis was accompanied by a lowering of the activity of Ca, Mg-ATPase of the sarcoplasmic reticulum coupled with an elevation of the content of lipid peroxidation products.
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PMID:[Function of the membrane lipids of the heart sarcoplasmic network in izadrin myocarditis studied by using a pyrene probe]. 316 Apr 11

In isadrin-induced myocarditis, the rat heart shows an increase in the activity of acid phosphatase, glucose-6-phosphate dehydrogenase. The heart weight also rises, whereas ATPase activity and magnesium content fall. Under these conditions strophanthin produces a marked decrease in acid phosphatase activity, stimulates the activity of glucoso-6-phosphate dehydrogenase, and demonstrates a tendency to increasing the activity of ATP-splitting enzymes, to reducing the activity of ATP-synthetase, and to the recovery of the magnesium content. Mefenamic acid and dexamethasone also decrease the activity of acid phosphatase but this decrease is less pronounced as compared with that induced by strophanthin. They exhibit the same tendency to the inhibition of glucoso-6-phosphate dehydrogenase. Mefenamic acid affects the remaining parameters similarly to strophanthin, while dexamethasone inhibits them.
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PMID:[Effects of strophanthin, mefenamic acid and dexamethasone on the inflammatory and reparative processes in the heart in experimental myocarditis]. 745 7

The concept of autoimmunity in the pathogenesis of myocarditis or dilated cardiomyopathy is gaining impetus. Since systolic functional impairment and subsequent recovery are frequently observed in myocarditis, we reasoned that the development of autoimmunity to cardiac sarcoplasmic reticulum calcium ATPase (SR-Ca2+ ATPase), which could interfere with intracellular calcium regulation and therefore affect myocardial contractility, should lead to immune-mediated myocarditis in experimental animals. Murine monoclonal antibody 4C11-20.21 (IgM class) generated against canine cardiac SR-Ca2+ ATPase inhibits the cardiac but not the skeletal ATPase activity. Immunization of CAF1/J mice with 4C11-20.21-affinity-column-purified cardiac SR-ATPase produced a time-dependent induction of myocardial injury consistent with the diagnosis of myocarditis. Furthermore, the antibody 4C11-20.21 alone can induce myo-necrosis in severe combined immunodeficiency (SCID) mice indicating a mechanism of cardiomyopathy independent of the cytotoxic T-cell mediated autoimmunopathy. Administration of 4C11-20.21 into immunocompetent CAF1/J mice resulted in minimal myocardial abnormality (40% with perivascular and/or interstitial mononuclear lymphoplasmacytoid aggregates, 10% with borderline myocarditis and 10% with lesions consistent with focal myocarditis). All control animals had normal hearts. Immunoperoxidase electron microscopic examination of the involved cardiac tissues showed antibody localization in the subsarcolemmal myotubular system and focal staining of the immediately adjacent sarcolemma in mice injected with 4C11-20.21 but not with 2C12.1B5. The time-dependent association between cardiac SR-Ca2+ ATPase administration and development of myocardial lesions, as well as potentiated induction of myonecrosis with anti-cardiac SR-Ca2+ ATPase antibody in SCID relative to immunocompetent mice, suggest a potential autoimmunopathogenic role of cardiac SR-Ca2+ ATPase in experimental myocarditis.
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PMID:SR-Ca2+ ATPase as an autoimmunogen in experimental myocarditis. 868 13

Norepinephrine and epinephrine stimulate alpha- and beta-adrenergic receptors which, in turn, modulate force of contraction in heart muscle cells. However, chronic stimulation may be associated with growth-promoting effects and modulation of the cardiac phenotype. Sympathetic tone is chronically enhanced in chronic heart failure and results in a selective down regulation of beta 1 adrenergic receptors, most likely due to local mechanisms. Beyond reduced beta 1 receptor density and increased levels of inhibitory Gi proteins, there is now evidence that NO can modulate the beta-adrenergic stimulation in the human myocardium. Increased NO activity generated by an inducible NO synthase is associated with a reduced positive inotropic response to beta-agonists, a mechanism which may play an important role in inflammatory states such as myocarditis or sepsis. Experimental data suggests that stimulation of alpha-adrenergic receptors of cardiomyocytes results in cardiac growth and changes in phenotype which, in turn, may affect the functional properties of the myocardium. For example, phenylephrine can upregulate the expression of the sodium/calcium exchanger, while the expression SR Ca2+ ATPase may be reduced. The latter is also affected by angiotensin II. Similar changes in the expression of these crucial proteins for the cardiac calcium homeostasis have been reported in the failing human heart, raising the possibility that the increased sympathetic tone and the activated renin-angiotensin system may be involved in these changes.
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PMID:[Sympathetic nervous system in heart failure: effect of catecholamines and nitric oxide]. 906 72

Myocardial inflammation contributes to the development of dilated cardiomyopathy, as well as other cardiac diseases. We have previously shown decreased left ventricular function in mice with autoimmune myocarditis. To test the hypothesis that decreased function is mediated by changes in contractility and/or Ca2+ cycling, we isolated cardiac myocytes from mice with myocarditis and age-matched controls at two time points: day 18 (prior to cardiac dysfunction) and day 35 (during cardiac dysfunction). We measured cell shortening and the Ca2+ transient simultaneously at 28 degrees C and 0.3 Hz. We also quantified proteins which regulate contractility and [Ca2+](i), using Western blot analysis. Results showed no change in cell shortening or systolic Ca2+ on day 18, despite a significant reduction in diastolic Ca2+. By day 35, the decrease in diastolic Ca2+ was accompanied by significantly reduced cell shortening and a decrease in the systolic Ca2+ transient. Protein levels of the sarcoplasmic reticulum Ca2+ ATPase were unchanged at both time points, while phospholamban and the sodium/calcium exchanger were significantly reduced in myosin-immunized mice at both time points. Calsequestrin was unchanged at day 18, but was significantly reduced in the myosin-immunized mice on day 35. Results of this study suggest that decreased diastolic Ca2+, as well as protein levels of phospholamban and the sodium/calcium exchanger, may actually contribute to disease progression in autoimmune myocarditis, while changes in calsequestrin may be related to systolic dysfunction in this model.
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PMID:Changes in calcium cycling precede cardiac dysfunction during autoimmune myocarditis in mice. 1118 Oct 14


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