Remodelamento miocárdico após grandes infartos converte potenciação pós-pausa em decaimento da força em ratos

Bocalini, Danilo Sales; Santos, Leonardo dos; Antônio, Ednei Luiz; Santos, Almira Alves dos; Davel, Ana Paula; Rossoni, Luciana Venturini; Vassalo, Dalto Valentim; Tucci, Paulo José Ferreira

doi:10.1590/s0066-782x2012005000016

Cited by 21 publications

(4 citation statements)

References 31 publications

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“…The maximum rate of force development during contraction (dF/dt max ) and the maximum rate of force decay during relaxation (dF/dt min ) were measured in all calcium concentrations. In order to evaluate the time dependence of the rest in the contractile force generated by the papillary muscles, post-rest potentiation (PRP) was measured by interrupting the electrical stimulation for 1, 3, 5, 10 and 20 seconds 14 . To measure the amount of potentiation, the force produced by the first contraction after the rest period was considered as PRP and normalized to previous steady state contraction.…”

Section: Methodsmentioning

confidence: 99%

Short-Term Thyroid Hormone Excess Affects the Heart but Does not Affect Adrenal Activity in Rats

Szkudlarek¹,

Aldenucci²,

Miyagui³

et al. 2014

Arquivos Brasileiros De Cardiologia

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BackgroundHyperthyroidism (Hy) exerts a broad range of influences on a variety of physiological parameters. Its disruptive effect on cardiovascular system is one of its most remarkable impacts. Moreover, Hy has been clinically associated with stress - induced hyperactivation of the hypothalamic-pituitary-adrenal axis.ObjectiveEvaluate the impact of short-term Hy on cardiac performance and adrenal activity of rats.MethodsInduction of Hy in Wistar rats through injections of T3 (150 µg/kg) for 10 days (hyperthyroid group - HG) or vehicle (control group). The cardiovascular performance was evaluated by: echocardiography (ECHO); heart weight/body weight (mg/gr) ratio; contractility of isolated papillary muscles (IPM) and direct measurement of blood pressures. Adrenal activity was evaluated by adrenal weight/body weight (mg/gr) ratio and 24-hour fecal corticosterone (FC) levels on the, 5th and 10th days of T3 treatment.ResultsIn HG, the ECHO showed reduction of the End Systolic and End Diastolic Volumes, Ejection, Total Diastolic and Isovolumic Relaxation Times, Diastolic and Systolic Areas and E/A ratio. Heart Rate, Ejection Fraction and Cardiac Output increased. The heart weight/body weight ratio was higher. Similarly, in IPM, the maximum rate of force decay during relaxation was higher in all extracellular calcium concentrations. Systolic blood pressure (SBP) levels were higher. (p ≤ 0.05). On the other hand, there was no difference in the adrenal weight/body weight ratio or in the 24-hour FC levels.ConclusionsHy induces positive inotropic, chronotropic and lusitropic effects on the heart by direct effects of T3 and increases SBP. Those alterations are not correlated with changes in the adrenal activity.

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Section: Methodsmentioning

confidence: 99%

Short-Term Thyroid Hormone Excess Affects the Heart but Does not Affect Adrenal Activity in Rats

Szkudlarek¹,

Aldenucci²,

Miyagui³

et al. 2014

Arquivos Brasileiros De Cardiologia

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“…Известно, что внутриклеточный механизм этого эффекта связан с Са 2+ -аккумулирующей способностью СР. [18]. При этом доказано, что во время периода покоя в результате работы Са 2+ -АТФ-азы происходит дополнительное накопление ионов кальция в СР.…”

Section: основные результаты исследованияunclassified

Structural and functional indicators of the heart of patients with ischemic heart disease and type 2 diabetes mellitus. Rhythmoinotropic response isolated myocardium at different levels of glycated hemoglobin

et al. 2021

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BACKGROUND: Adequate glycemic control can significantly reduce the risk of developing cardiovascular events. However, until now, glycaemic targets in aged patients remain a subject of discussion, especially in the conditions of the combined development of Type 2 Diabetes Mellitus (T2DM) and ischemic heart disease (IHD).AIMS: To examine the structural and functional heart parameters in patients with IHD associated with T2DM and the rhythmoinotropic responses of their isolated myocardium depending on glycated hemoglobin level.MATERIALS AND METHODS: The study included 44 patients with a diagnosis of "chronic IHD associated with T2DM", of which 2 groups were formed. Patients with glycated hemoglobin level (HbA1c) <8% were included in the 1st group, and patients with HbA1c ≥8% were included in the 2nd group. The structural and functional heart parameters obtained with ultrasonography, and the rhythmoinotropic responses of myocardium in patients ex vivo were analyzed using the right atrial appendage fragments obtained during elective coronary artery bypass graft. The inotropic response of muscle strips at a basic stimulation frequency of 0,5 Hz to testing influences was assessed. An extrasystolic test and post-rest test were performed.RESULTS: It was found that extrasystolic contractions of isolated myocardial strips in patients of the 2nd group appeared at shorter extrasystolic intervals, which indicates a greater excitability of the myocardium in patients of this group. Postextrasystolic muscle contractions in patients of the 2nd group had significant potentiation. The amplitude of the muscle strips contractions in patients of both groups was potentiative after short rest periods. However, with an increase in the rest duration, potentiation of contractions was observed only in the group with a higher HbA1c level. According to the ultrasonography data, it was found that the values of the endsystolic and diastolic volumes, the interventricular septum thickness and the left ventricular (LV) myocardium mass were significantly lower in the patients of the 1st group compared with the corresponding indicators in the patients of the 2nd group. The early LV filling velocity (peak E) was significantly lower in the patients of the 1st group, which indicates a slower LV relaxation. At the same time, the rapid LV filling velocity did not have a significant intergroup difference, but this indicator exceeded the reference values in both groups.CONCLUSIONS: With a moderately increased glycemic level (9,2 [8,0; 10,3]%), the structural and functional heart parameters are preserved both at the level of the isolated myocardial tissue and at the level of the whole heart.

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“…Immediately after blood sample collection, the heart was quickly removed and placed in oxygenated Krebs-Henseleit nutrient solution. As detailed elsewhere [14,15], the papillary muscle of the left ventricle was carefully dissected and mounted vertically in a chamber containing nutrient solution oxygenated with 100% O 2 at 30 o C and pH adjusted to 7.40. The composition of the solution was (mmol/l): NaCl 132; KCl 4.69; CaCl 2 1.5; MgSO 4 1.16; KH 2 PO 4 1.18; C 6 H 12 O 6 5.50; HEPES 20.…”

Section: 'In Vitro' Cardiac Muscle Mechanicsmentioning

confidence: 99%

Physical exercise attenuates stress-induced hypertension in rats but not the impairments on the myocardial mechanics

Silva

Perilhão

Portes

et al. 2021

Journal of Hypertension

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Background: Acute and chronic stresses have become a health problem in the contemporary society, and prolonged exposure to stressful events are related to the pathogenesis of cardiovascular diseases. Physical exercise is a well-recognized effective nonpharmacological therapy for cardiovascular diseases and stress-induced injuries. Thus, this study evaluated the effect of exercise on the cardiac remodelling of chronically stressed rats.Methods and results: Wistar adult rats were used (n ¼ 10 each group) and chronic stress protocol consisted of restricting movement in individual rodent restrainers (60 min, 5 days/week, 12 weeks); and exercise consisted of swimming sessions in a pool (60 min, 5 days/week, 12 weeks). During protocol, blood pressure was measured in conscious rats, and at the end cardiac morphology/ function was assessed. Animals exposed to stress exhibited continuous rise in blood pressure from the sixth week, but exercise attenuated it. Similarly, restrained rats increased serum corticosterone compared with nonstressed rats, but exercise also prevented it. No changes were found in cardiac mass, but chronic stress not only impaired the steady state contractions of the cardiac muscle, but also reduced inotropic responses to stretching, increasing calcium and beta-adrenergic receptor stimulation. Despite this, exercise was unable to prevent these functional impairments induced by stress, and instead, the association of stress and physical exercise worsened myocardial compliance. Conclusion:Despite the known benefits to the cardiovascular system, our results indicate that aerobic swimming exercise for 12 weeks reduced blood pressure but did not impede the chronic stress-induced myocardial damages in rats.

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Remodelamento miocárdico após grandes infartos converte potenciação pós-pausa em decaimento da força em ratos

Abstract: Background: Post-rest contraction (PRC) of cardiac muscle provides indirect information about the intracellular calcium handling.

Cited by 21 publications

References 31 publications

Short-Term Thyroid Hormone Excess Affects the Heart but Does not Affect Adrenal Activity in Rats

Short-Term Thyroid Hormone Excess Affects the Heart but Does not Affect Adrenal Activity in Rats

Structural and functional indicators of the heart of patients with ischemic heart disease and type 2 diabetes mellitus. Rhythmoinotropic response isolated myocardium at different levels of glycated hemoglobin

Physical exercise attenuates stress-induced hypertension in rats but not the impairments on the myocardial mechanics

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