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Biomedical subjects

I Edes

Publications and source records attributed to I Edes.

At least 19 recordsLinked to original sources
PubMed2004

Effects of Ca2+ -sensitizers in permeabilized cardiac myocytes from donor and end-stage failing human hearts.

During heart failure, alterations occur in contractile protein expression and phosphorylation, which may influence the effects of Ca2+ -sensitizers. To quantify the magnitude of these effects, isometric force was studied in mechanically isolated Triton-skinned myocytes from end-stage failing and non-failing donor hearts under control conditions (pH 7.2; no added inorganic phosphate (Pi)) and under mimicked ischemic conditions (pH 6.5; 10 mM Pi). Two different Ca2+ -sensitizers were used: EMD 53998 (10 microM), which exerts its influence through the actin-myosin interaction, and OR-1896 (10 microM) (the active metabolite of levosimendan), which affects the Ca2+ -sensory function of the thin filaments. The maximal force (Po) measured at saturating Ca2+ concentration and the resting force (Prest) determined in the virtual absence of Ca2+ (pCa 9) did not differ between the failing and non-failing myocytes, but the Ca2+ concentration required to induce the half-maximal force under control conditions was significantly lower in the failing than in the non-failing myocytes (DeltapCa50=0.15). This difference in Ca2+ -sensitivity, however, was abolished during mimicked ischemia. EMD 53998 increased Po and Prest by approximately 15% of Po and greatly enhanced the Ca2+ -sensitivity (DeltapCa50 > 0.25) of force production. OR-1896 did not affect Po and Prest, and provoked a small, but significant Ca2+ -sensitization (DeltapCa50 approximately 0.1). All of these effects were comparable in the donor and failing myocytes, but, in contrast with OR-1896, EMD 53998 considerably diminished the difference in the Ca2+ -sensitivities between the failing and non-failing myocytes. The action of Ca2+ -sensitizers under mimicked ischemic conditions was impaired to a similar degree in the donor and the failing myocytes. Our results indicate that the Ca2+ -activation of the myofibrillar system is altered in end-stage human heart failure. This modulates the effects of Ca2+ -sensitizers both under control and under mimicked ischemic conditions.

Acetamides↗
PubMed2003

The cardiotonic effects of levosimendan in guinea pig hearts are modulated by beta-adrenergic stimulation.

The effects of the Ca2+-sensitiser levosimendan alone or in combination with beta-adrenergic stimulation on the contractile function were studied in various guinea pig cardiac preparations. Echocardiography in narcotised animals indicated that a maximal dose of levosimendan (50 microg x kg(-1)) increased the left ventricular posterior wall movement velocity during systoles and diastoles by 25 +/- 3% (mean +/- S.E.M.) and 17 +/- 2%, respectively. In Langendorff hearts, a saturating concentration of levosimendan (0.3 micromol x l(-1) for 5 min) increased +dP/dt(max) and dP/dt(max) by 28 +/- 3% and 14 +/- 2%, respectively. Further, the Ca2+-sensitising potential of levosimendan in Triton-skinned cardiomyocytes (EC50: 5 +/- 3 nmol x l(-1)) was illustrated by a maximal increase in the isometric force production by 51 +/- 5% (at pCa 6.2). However, following stimulation by isoproterenol, when the level of troponin I phosphorylation was elevated, no significant additional increase in the contractile parameters could be demonstrated upon levosimendan administration. Moreover, the levosimendan-induced increase in force production in isolated skinned myocytes could be prevented by incubation with the catalytic subunit of protein kinase A (100 U x ml(-1) for 40 min). These data indicate that thin filament-targeted Ca2+-sensitisation by levosimendan is modulated by phosphorylation of the contractile filaments, an effect that should be considered during combination therapy with levosimendan.

Adrenergic beta-Agonists↗
PubMed2001

[Role of beta-blockers in the treatment of chronic heart heart failure].

Role of beta-blockers in the treatment of chronic heart failure has been changed over a 25-year period from contraindication to an established indication. To date, controlled clinical trials performed in more than 13,000 patients with chronic heart failure have consistently shown that the long term administration of beta-blockers is associated with significant improvement in left ventricular function, clinical symptoms, and survival. This favorable clinical trial experiences support a recommendation that beta-blockers should be used in all heart failure patients with stable symptoms due to left ventricular systolic dysfunction unless contraindicated. Ongoing beta-blocker studies address further new topics, such as treatment of elderly patients and direct comparison of different agents. Although, the use of beta-blockers for heart failure tends to increase, implementation of the experiences from the clinical trials to the everyday practice still remains a challenge.

Adrenergic beta-Antagonists↗
PubMed2001

Deterioration of the protein kinase C-K(ATP) channel pathway in regulation of coronary flow in hypercholesterolaemic rabbits.

We studied the effect of experimental hypercholesterolaemia/atherosclerosis on changes in coronary flow and cardiac function, induced by protein kinase C and ATP-sensitive K(+) (K(ATP)) channel modulators in isolated Langendorff-perfused rabbit hearts. Both phorbol 12-myristate-13-acetate (PMA) and phorbol 12,13-dibutyrate (PDB, 0.1 microM each), activators of protein kinase C, decreased, whereas staurosporine, (0.1 microM), a protein kinase C inhibitor, increased coronary flow and left ventricular dP/dt, an index of ventricular contractility. Glyburide (5-50 microM), a K(ATP) channel inhibitor, blocked the effect of staurosporine. The phorbol esters were without effect in the presence of pinacidil (5 microM), a K(ATP) channel activator. Neither the protein kinase C modulators nor glyburide produced any effect on coronary flow and left ventricular contractility, when the hearts were prepared from animals either maintained on a cholesterol (1.5%)-enriched diet or treated with lovastatin (5 mg/kg/day per os). Treatment with farnesol (1 mg/kg twice a day for 7 days intravenously) restored the reactivity of hearts from either hypercholesterolaemic or lovastatin-treated animals to protein kinase C modulators. We conclude that non-cholesterol mevalonate products are necessary for the functional integrity of the protein kinase C-K(ATP) channel pathway in the rabbit heart.

Adenosine Triphosphate↗
PubMed2001

Phospholamban: a promising therapeutic target in heart failure?

Dilated cardiomyopathy and end-stage heart failure result in characteristic functional, biochemical and molecular alterations. Multiple defects in cardiac excitation-contraction coupling have been suggested to underlie disturbed myocardial function and progressive remodeling. Ca2+ uptake and release by the sarcoplasmic reticulum (SR) have been shown to be altered in various animal models and human conditions. This review will focus on SR Ca2+ ATPase and its regulatory protein, phospholamban, as potential therapeutic targets. We summarize structural and genetic approaches, which have helped to elucidate the physiological role of phospholamban as a principal regulator of cardiac contractility and beta-adrenergic stimulation in the heart. These findings are extended to the clinical arena, indicating a phospholamban/SR Ca2+ ATPase mismatch in human heart failure. Evidence is then provided, using genetically engineered mouse models, that SR dysfunction may play a key role in the onset and progression of heart failure. Phospholamban deficiency may prevent such left ventricular dysfunction and its progression to heart failure in some of the animal models with dilated cardiomyopathy. Based on these findings, we discuss the question of whether and how interfering with the phospholamban/SR Ca2+ ATPase interaction may be a promising therapeutic approach for heart failure.

Animals↗
PubMed2000

Differences in the changes of allergen-specific IgE serum levels and the chemiluminescence of peripheral blood phagocytes in patients with allergic rhinoconjunctivitis during the ragweed season.

The objective of this study was to compare the changes in the values of allergen-specific serum IgE levels and zymosan-induced whole blood chemiluminescence (CL) in 41 patients who had exclusively only ragweed allergy in the season of acute symptoms of disease in July, August and September. All patients had allergic rhinitis or rhinoconjunctivitis. Each patient was investigated as a self-control. The ragweed-specific IgE levels were measured by enzyme immunoassay (EIA). The luminol amplified zymosan-induced CL of whole human blood was detected. The allergen-specific serum IgE levels showed slight, but not significant, gradually increasing elevations during the whole season. On the other hand, significant increases were found in the values of the basal but especially in the zymosan-stimulated CL of peripheral blood phagocytes during the acute phase of allergy. Both the basal and the zymosan-induced CL reflected significantly the activated state of the immune system. These observations clearly show that there are well detectable signs of the systemic activation of the immune system in allergic rhinoconjunctivitis beside the local alterations. In addition, the measurements of the basal and zymosan-induced CL of peripheral phagocytes could clearly reflect the clinical state of disease in vitro.

Adult↗
PubMed1999

[Improvement of myocardial perfusion following left ventricular resection].

Left ventricular aneurysm had detected at the 55-year-old woman after extensive anterior myocardial infarction in association with progressive ventricular dilatation and symptoms of heart failure. Coronary angiogram revealed a serious lesion in the proximal segment of the left anterior descending coronary branch with a poor run off tract. 18FDG-PET and 99mTc-MIBI-SPECT investigation were performed in order to differentiate the scarred regions from the viable myocardial segments. Taking into consideration the results an aneurysm resection was performed without revascularisation procedure. After the surgery not only the ejection fraction and the left ventricular dilatation had improved but the tissue perfusion in the segments surrounding the resected aneurysm had also showed a significant increase at the follow up MIBI-SPECT imaging.

Coronary Angiography↗
PubMed1999

The effect of isoproterenol on phospholamban-deficient mouse hearts with altered thyroid conditions.

The aim of the present study was to determine the effects of beta -adrenergic stimulation in wild-type and phospholamban-deficient mouse hearts with altered thyroid conditions. Hypothyroidism was associated with significant decreases in heart/body weight ratio in wild-type and phospholamban-deficient mice, whereas hyperthyroidism was associated with significant increases in heart/body weight ratio in both groups. Hypothyroid hearts of wild-type and phospholamban-deficient mice exhibited similar increases in beta -myosin heavy chain protein levels and decreases in alpha -myosin heavy chain protein levels. In hyperthyroidism, there were increases in the alpha -myosin heavy chain protein levels and these were similar in wild-type and phospholamban-deficient hearts. There were no detectable levels of beta -myosin heavy chain protein in the hyperthyroid hearts. The relative tissue level of phospholamban in wild-type hearts was increased (133%, P<0.01) in hypothyroidism, and decreased (69%, P<0.01) in hyperthyroidism, when compared to euthyroid controls (100%). Similar increases and decreases in SR Ca(2+)-ATPase protein levels were observed between phospholamban-deficient and wild-type hearts in hyperthyroidism and hypothyroidism, respectively. The basal contractile state of wild-type and phospholamban-deficient hearts was significantly depressed in hypothyroidism. On the other hand, the basal contractile state of wild-type and phospholamban-deficient hearts was significantly increased in hyperthyroidism. During beta -agonist stimulation of wild-type hearts, the responses in the rates of contraction and relaxation were highest in the hypothyroid group, followed by the euthyroid, and lastly by the hyperthyroid groups. There was a close linear correlation between the magnitude of the contractile parameter responses and the phospholamban/SERCA2 ratios in these hearts. However, the phospholamban-deficient hypothyroid, euthyroid, and hyperthyroid hearts did not exhibit any responses to isoproterenol, indicating that the alterations in the thyroid states of these hearts do not influence the effects of isoproterenol on cardiac function. These findings suggest that phospholamban is an important regulator of the heart's responses to beta -adrenergic stimulation under various thyroid states.

Animals↗
PubMed1999

The effects of levosimendan on the left ventricular function and protein phosphorylation in post-ischemic guinea pig hearts.

The widely accepted theories for the decreased function in the stunned myocardium relate to Ca2+ desensitization and free radical-mediated tissue damage of the myofilaments. The aim of the present study was to examine whether the depressed contractile function and Ca2+ responsiveness of the stunned myocardium may be restored by a new Ca2+ sensitizer (levosimendan), which has been shown to improve the Ca2+ response of the myofilaments. The effects of levosimendan on the left ventricular function and the in vivo protein phosphorylation were examined in both the non-ischemic and the stunned myocardium. Myocardial stunning was induced in Langendorff-perfused guinea pig hearts by suspending the circulation for 8 min, followed by a 20-min reperfusion period. Perfusion of post-ischemic guinea pig hearts with levosimendan (0.03-0.48 microM, 6 min) was associated with dose- and time-dependent increases in both dP/dtmax (contractility) and dP/dtmin (speed of relaxation). When the effectiveness of levosimendan was compared in non-ischemic and post-ischemic hearts, no significant differences were noted in the relative stimulatory effects on contractility and relaxation, at any given time point (time-response curve) or concentration (dose-response curve). Perfusion of the guinea pig hearts with a high (0.3 microM) levosimendan concentration did not reveal any qualitative or quantitative difference in the phosphodiesterase inhibitory potential of the compound (elevation of tissue cyclic AMP levels and characteristics of protein phosphorylation) between the non-ischemic and the post-ischemic myocardium. However, when isoproterenol was administered to induce maximal in vivo phosphorylation of cardiac phosphoproteins, an attenuation of the 32P-incorporation into troponin I was noted in the post-ischemic hearts. The decrease in isoproterenol-induced 32P-incorporation into troponin I was associated with similar alterations in the tissue level of this protein. We conclude that the Ca2+ sensitizer levosimendan exerts dose- and time-dependent positive inotropic and lusitropic effects on the post-ischemic myocardium, lending support to the hypothesis tha Ca2+ desensitization of the myofibrils is involved in myocardial stunning.

Animals↗
PubMed1998

Thyroid hormone-induced alterations in phospholamban-deficient mouse hearts.

Alterations in the expression levels of the sarcoplasmic reticulum (SR) Ca2+-ATPase and its regulator, phospholamban, have been implicated in the effects of thyroxine hormone on cardiac function. To determine the role of phospholamban in these effects, hypothyroidism and hyperthyroidism were induced in phospholamban-deficient mice and their isogenic wild types. Hypothyroidism resulted in significant decreases of left ventricular contractility, which could be moderately stimulated by increases in preload or afterload, in both phospholamban-deficient and wild-type mice. However, the basal contractile parameters in hypothyroid phospholamban-deficient hearts were at least as high as those exhibited by hyperthyroid wild-type hearts. In hyperthyroidism, there was no further enhancement of the hyperdynamic contractile parameters in phospholamban-deficient hearts, although the wild-type hearts exhibited significantly increased contractile function compared with their respective euthyroid groups. Furthermore, increases in preload or afterload did not enhance contractility in either phospholamban-deficient or wild-type hyperthyroid hearts. Examination of the relative tissue levels of cardiac SR Ca2+-ATPase revealed increases in hyperthyroidism and decreases in hypothyroidism compared with euthyroidism, and these changes were similar between phospholamban-deficient and wild-type hearts. An opposite trend was observed for phospholamban expression levels in the wild-type group, which were depressed in hyperthyroid hearts but increased in hypothyroid hearts. These findings indicate that (1) thyroid hormones induce similar changes in the cardiac SR Ca2+-ATPase levels in either the presence or absence of phospholamban, (2) the thyroxine-induced increases in SR Ca2+-ATPase levels are not associated with any further stimulation of the hyperdynamic cardiac function in phospholamban-deficient mice, and (3) the decreased contractile parameters in hypothyroid phospholamban-deficient hearts associated with decreases in SR Ca2+-ATPase levels and myosin heavy chain isoform switches are at least as high as those of the stimulated hyperthyroid wild-type hearts. Thus, alterations in the phospholamban level or its activity may be a critical determinant of the contractile responses to altered thyroid states in the mammalian heart.

Animals↗
PubMed1998

Phospholamban ablation and compensatory responses in the mammalian heart.

Phospholamban is a low molecular weight phosphoprotein in cardiac sarcoplasmic reticulum. The regulatory role of phospholamban in vivo has recently been elucidated by targeting the gene of this protein in embryonic stem cells and generating phospholamban-deficient mice. The phospholamban knockout hearts exhibited significantly enhanced contractile parameters and attenuated responses to beta-agonists. The hyperdynamic cardiac function of the phospholamban knockout mice was not accompanied by any cytoarchitectural abnormalities or alterations in the expression levels of the cardiac sarcoplasmic reticulum Ca(2+)-ATPase, calsequestrin, Na(+)-Ca2+ exchanger, or the contractile proteins. Furthermore, the attenuation of the cardiac responses to beta-agonists was not due to alterations in the phosphorylation levels of the other key cardiac phosphoproteins in the phospholamban knockout hearts. However, ablation of phospholamban was associated with down-regulation of the ryanodine receptor, which suggests that a cross-talk between cardiac sarcoplasmic reticulum Ca2+ uptake and Ca2+ release occurred in an attempt to maintain Ca2+ homeostasis in these hyperdynamic phospholamban knockout hearts.

Adrenergic beta-Agonists↗
PubMed1997

[Prediction of the result of high-risk coronary bypass surgery by positron emission tomography].

Coronary angiography revealed three-vessel disease in a 56-year-old male with two previous myocardial infarctions. Coronary bypass surgery was initially ruled out by cardiac surgeon because of the poor left ventricular function (EF: 23%), despite moderate viability signs during conventional isotope techniques. Positron emission tomography with 18FDG indicated a large periinfarction area of hibernating myocardium. Accordingly, coronary bypass grafting was performed. Postoperatively, the symptoms disappeared, the left ventricular wall motion abnormalities (with the exception of the scarred region demonstrated by PET) improved, and the global left ventricular function increased significantly. This case and the role of cardiac PET study for prediction of the result of revascularization are discussed.

Coronary Angiography↗
PubMed1997

Postinfarction left ventricular pseudoaneurysm.

Left ventricular wall rupture after myocardial infarction is a mechanical complication that may result in a pseudoaneurysm. Between January 1994 and October 1996, false or pseudoaneurysms were detected in 6 (0.0026%) of 2,600 consecutive patients (4 women, 2 men; mean age 59.4 years) undergoing cardiac catheterization at University Medical School, Debrecen, Hungary. All patients had a history of cardiovascular disease, with diagnosis of pseudoaneurysm confirmed by echocardiography. The average time from the occurrence of acute infarction to diagnosis was 37.0 days (range 3-80 days). All patients were in New York Heart Association functional class IV congestive heart failure; in four patients cardiogenic shock was present. Five patients underwent coronary angiography, which demonstrated multivessel disease and occlusion of the infarct-related artery (TIMIO) without adequate collateral circulation (grade 0-1). Five patients had surgical repair of the false aneurysm, and, in three patients, concomitant coronary bypass grafting was performed. The 2-year mortality rate for all patients was 50%. Early diagnosis of false aneurysm is facilitated by echocardiography, and coronary angiography is required before surgery. Early surgical correction with coronary revascularization is advised.

Aged↗
PubMed1997

beta-Adrenergic regulation of cAMP and protein phosphorylation in phospholamban-knockout mouse hearts.

The stimulatory effects of beta-adrenergic agonists reflect increases in intracellular adenosine 3',5'-cyclic monophosphate (cAMP) levels and phosphorylation of key regulatory proteins in the heart. One of these phosphoproteins is phospholamban (PLB) in sarcoplasmic reticulum, and ablation of PLB is associated with attenuation of the contractile responses to beta-adrenergic stimulation in the mouse heart. To determine whether this attenuation of beta-stimulation is due to altered phosphorylation characteristics of the other key cardiac phosphoproteins and/or to compensatory responses occurring in the absence of PLB, PLB-knockout and wild-type hearts were perfused and their protein phosphorylation patterns examined. The beta-adrenergic receptor density, adenylyl cyclase activity, tissue cAMP levels, and the basal phosphoprotein pattern were similar between PLB-knockout and wild-type hearts. Isoproterenol perfusion resulted in similar increases in the tissue cAMP levels and the degree of phosphorylation of troponin I, C protein, and the 21-kDa microsomal protein in wild-type and PLB-knockout hearts. These findings indicate that the attenuation of isoproterenol-mediated increases in contractility of the PLB-knockout hearts is not due to alterations in the beta-adrenergic signal transduction pathway or the degree of phosphorylation of the key cardiac regulatory phosphoproteins in myofibrils and sarcolemma.

Animals↗
PubMed1995

[Angiographic findings in postinfarction cardiac rupture].

The hemodynamic and angiographic findings were examined in 16 patients with myocardial rupture following acute myocardial infarction. The patients (9 men, mean age 55.8 years, and 7 women, mean age 64.0 years) had suffered an extensive transmural infarction, all but 2 cases involved first cardiac events. The diagnosis of myocardial rupture was made on clinical grounds, and confirmed by the results of noninvasive (echocardiography) and invasive (left ventriculography) investigations. The average time from the infarction to the appearance of cardiac rupture was 4.6 days (range: 1 hour to 16 days). The patients receiving thrombolytic therapy mainly suffered an early rupture (less than 72 hours following the infarction), while the group receiving conventional therapy mainly had a late rupture (between 4 and 16 days). 7 patients had single-vessel, 3 two-vessel and 6 three-vessel disease. Examination of the infarct-related vessel revealed a total occlusion in the proximal or medial part of the coronary in 75% of the cases. Angiography demonstrated no manifest collateral circulation to the infarct-related artery in 10 cases, and only limited collateral blood flow in 6 patients. It is concluded that cardiac rupture depends on the management of the myocardial infarction, the abrupt cessation of flow in the infarct-related vessel and the absence of adequate collateral circulation supporting the infarcted zone. 15 patients underwent cardiac surgical correction and in 8 cases additional coronary artery bypass grafting was performed. After the operative intervention, 9 patients exhibited a significant improvement, and there was no sign of cardiac failure.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1995

Effects of Levosimendan, a cardiotonic agent targeted to troponin C, on cardiac function and on phosphorylation and Ca2+ sensitivity of cardiac myofibrils and sarcoplasmic reticulum in guinea pig heart.

A new cardiotonic agent, (R)-[[4-(1,4,5,6-tetrahydro-4-methyl-6-oxo-3-pyridazinyl)-phenyl] hydrazono]propanedinitrile (Levosimendan), has been developed and screened for its ability to bind to cardiac troponin C. In perfused hearts, low concentrations of 0.03 or 0.1 mumol/L Levosimendan increased +dP/dt, but did not affect the speed of relaxation and produced only a slight increase in spontaneous heart rate in the hearts perfused with 0.1 mumol/L of the drug. In these same hearts, perfusion with 0.03 mumol/L Levosimendan did not alter the 32P incorporation into troponin I or C protein, whereas a slight but significant increase was noted for phospholamban, with no detectable change in tissue cAMP levels. Administration of 0.1 or 0.3 mumol/L Levosimendan significantly increased myocardial cAMP levels as well as the phosphorylation of phospholamban, troponin I, and C protein. Levosimendan (0.03 to 10 mumol/L) reversibly increased force generated by detergent-extracted fiber bundles over a range of submaximally activating free Ca2+ concentrations with no significant effect on maximum force or on Ca2+ binding to myofilament troponin C. There was no direct effect of Levosimendan on Ca2+ uptake by vesicles of sarcoplasmic reticulum (SR). In contrast, under conditions optimal for cAMP-dependent phosphorylation, Levosimendan slightly but significantly lowered the concentration of Ca2+, yielding half-maximal uptake rates by the SR vesicles. Our results indicate that at low concentrations Levosimendan acts preferably as a Ca2+ sensitizer, whereas at higher concentrations its action as a phosphodiesterase inhibitor contributes to the positive inotropic effect.

Analysis of Variance↗
PubMed1994

Thyroid hormone-induced alterations in phospholamban protein expression. Regulatory effects on sarcoplasmic reticulum Ca2+ transport and myocardial relaxation.

The aim of the present study was to determine the changes in phospholamban protein levels and their regulatory effect on sarcoplasmic reticulum (SR) Ca2+ uptake and left ventricular function in hypothyroid and hyperthyroid rat hearts. Hypothyroidism was associated with decreases in basal left ventricular function (+dP/dt and -dP/dt), whereas in hyperthyroidism these parameters were elevated compared with values for euthyroid hearts. The maximal SR Ca2+ uptake rates were 12.8 +/- 1.1, 15.5 +/- 1.2, and 21.4 +/- 1.4 nmol Ca2+ per milligram per minute, and the EC50 values for Ca2+ were 0.76 +/- 0.09, 0.41 +/- 0.07, and 0.30 +/- 0.05 mumol/L assayed in homogenates from hypothyroid, euthyroid, and hyperthyroid hearts, respectively. The relative tissue level of phospholamban was increased (135%) in hypothyroidism and decreased (75%) in hyperthyroidism compared with euthyroidism (100%). An opposite trend was observed for the SR Ca(2+)-ATPase, which was depressed (74%) in hypothyroid hearts but increased (134%) in hyperthyroid hearts. Consequently, the relative ratio of phospholamban to Ca(2+)-ATPase was highest in hypothyroid and lowest in hyperthyroid hearts, and these changes correlated with changes in the EC50 of the SR Ca2+ uptake for Ca2+. Stimulation of hearts with 0.1 mumol/L isoproterenol revealed that the relaxant effects were lower in hyperthyroid hearts and higher in hypothyroid hearts compared with euthyroid hearts, consistent with the alterations in the phospholamban levels. The maximal increases in the speed of relaxation, elicited by isoproterenol stimulation, correlated with the changes in the relative ratio of phospholamban to Ca(2+)-ATPase in these hearts.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphatases↗