The Effect of Adrenaline-Induced Endogenous Lipolysis upon the Mechanical and Metabolic Performance of Ischaemically Perfused Rat Hearts

1977 ◽  
Vol 53 (6) ◽  
pp. 513-521
Author(s):  
R. W. Brownsey ◽  
R. V. Brunt
Keyword(s):  
Heart Rate ◽  
Mechanical Performance ◽  
Slight Reduction ◽  
Marked Rise ◽  
Tension Development ◽  
Mechanical Responses ◽  
Resting Tension ◽  
Rat Hearts ◽  
Perfused Rat Hearts ◽  
Metabolic Performance

1. The isolated perfused non-working rat heart, subjected to low coronary flow, has been used to study the effects of myocardial ischaemia on both the mechanical and metabolic performance of the heart. 2. In this preparation, adrenaline initially increased developed tension and heart rate, followed shortly thereafter by marked deterioration in mechanical performance to levels below those observed in the control state. These latter responses occurred simultaneously with stimulation of endogenous myocardial lipolysis. The rate of release of non-esterified fatty acids was positively correlated with both the decline in developed tension and the rise in resting tension. 3. The anti-lipolytic agent nicotinic acid had no effect on the initial mechanical responses of the heart to adrenaline but prolonged the period of enhanced tension development after adrenaline and reduced the degree of later deterioration in performance, in addition to blocking lipolytic stimulation. 4. Hearts from rats fed on a diet rich in animal fat contained larger triglyceride reserves and exhibited greater rates of non-catecholamine-stimulated lipolysis than hearts from normally fed rats. During ischaemic perfusion such hearts showed a more marked rise in resting tension and decline in heart rate than hearts from normally fed animals. Such hearts also had an increased incidence of arrhythmias and a slight reduction in developed tension. The initial responses of these hearts from fat-fed rats to adrenaline were also depressed as compared with normal hearts. Hearts from fat-fed rats showed a greater tendency to deteriorate in performance after adrenaline, particularly with falling heart rates and the onset of ventricular fibrillation. 5. We suggest that these results indicate that myocardial lipolysis makes a significant contribution to the adrenaline-induced deterioration in performance seen in these ischaemically perfused rat hearts.

Chaotic Heart Rate Dynamics in Isolated Perfused Rat Hearts

1989 ◽  
pp. 215-224 ◽  
Author(s):  
Joseph P. Zbilut ◽  
Gottfried Mayer-Kress ◽  
Paul A. Sobotka ◽  
Michael O’Toole ◽  
John X. Thomas
Keyword(s):  
Heart Rate ◽  
Rat Hearts ◽  
Heart Rate Dynamics ◽  
Perfused Rat Hearts ◽  
Isolated Perfused Rat Hearts

Altered Ca2+ handling and myofilament desensitization underlie cardiomyocyte performance in normothermic and hyperthermic heat-acclimated rat hearts

2007 ◽  
Vol 103 (1) ◽  
pp. 266-275 ◽  
Author(s):  
Omer Cohen ◽  
Hifa Kanana ◽  
Ronen Zoizner ◽  
Chaya Gross ◽  
Uri Meiri ◽  
...  
Keyword(s):  
Mechanical Performance ◽  
Ryanodine Receptors ◽  
Pool Size ◽  
Force Generation ◽  
Isolated Hearts ◽  
Rat Hearts ◽  
Metabolic Performance ◽  
And Control ◽  
Negative Inotropic Response ◽  
Beating Frequency

Heat acclimation (AC) improves cardiac mechanical and metabolic performance. Using cardiomyocytes and isolated hearts from 30-day and 2-day acclimated rats (AC and AC-2d, 34°C), we characterized cellular contractile mechanisms under normothermic (37°C) and hyperthermic (39–42°C) conditions. To determine contractile responses, Ca2+ transients (Ca2+ T), sarcoplasmic reticulum (SR) Ca2+ pool size (fura-2/indo-1 fluorescence), force generation [amplitude systolic motion (ASM)], L-type Ca2+ channels [dihydropyridine receptor (DHPR)], ryanodine receptors (RyRs), and total (PLBt) and phosphorylated phospholamban [serine phosphorylated (PLBs) and theonine phosphorylated (PLBtr)] proteins and transcripts were measured (Western blot, RT-PCR). Cardiac mechanical performance was measured using a Langendorff system. We demonstrated that AC and AC-2d increased Ca2+ T amplitude (148% and 147%, respectively) and twitch force (180% and 130%, respectively) and desensitized myofilaments, as indicated by a rightward shift in the ASM-Ca2+ relationships, despite no change in SR Ca2+ pool size. Hence, generation of higher Ca2+ T underlies greater force development in AC and AC-2d myocytes. In isolated hearts, ryanodine administration eliminated differences between AC and control (C) hearts, implying an important role for RyRs in that acclimation phase. Increased expression of DHPR and RyRs, and decreased PLBs/PLBt in AC hearts only, suggest that different pathways increase force generation in the AC-2d vs. AC myocytes. At basal beating rates, hyperthermia (39–41°C) enhanced pressure generation in AC hearts. C hearts failed to restitute pressure beyond 39°C. Increased beating frequency produced negative inotropic response. In C cardiomyocytes, hyperthermia elevated basal cytosolic Ca2+ and tension, Ca2+ T, and ASM. AC myocytes enhanced Ca2+ T but showed myofilament desensitization, suggesting its involvement in cardiac protection against hyperthermia. Collectively, both Ca2+ turnover and myofilament responsiveness are important adaptive acclimatory targets during normothermic and hyperthermic conditions.

Effect of perfusate Ca2+ on the relation between metabolism and mechanical performance in the rat heart

1980 ◽  
Vol 58 (5) ◽  
pp. 570-573 ◽  
Author(s):  
T. Russell Snow ◽  
Gabor Rubanyi ◽  
Tunde Dora ◽  
Eörs Dora ◽  
Arisztid G. B. Kovach
Keyword(s):  
Respiratory Chain ◽  
Mechanical Performance ◽  
Left Ventricular ◽  
Perfused Heart ◽  
Exogenous Substrate ◽  
Rat Hearts ◽  
Nadh Fluorescence ◽  
Perfused Rat Hearts ◽  
Developed Pressure ◽  
Contractile Performance

Langendorf perfused rat hearts (n = 25) were used to study the effects of changes in perfusate Ca2+ concentration ([Ca2+p]) on the relation between metabolism and mechanical performance with either glucose or pyruvate as the exogenous substrate. Increased [Ca2+p] (from 1.3 to 3.9 mM) produced an increase (243 ± 38%) in left ventricular developed pressure regardless of the substrate. With glucose as the substrate, the NADH fluorescence intensity increased by 11.8 ± 1.2% (n = 17) relative to control indicating a more reduced state of the respiratory chain. Increasing [Ca2+p] in the pyruvate perfused heart produced the expected NADH oxidation (−6.2 ± 1.1%; n = 8). Hence the change in NADH fluorescence associated with increased [Ca2+p] is substrate dependent. The data show that, with glucose as the substrate but not with pyruvate, increases in [Ca2+p] increase the availability of reducing equivalents to the respiratory chain above the level necessary to compensate for the increased demand resulting from the greater contractile performance.

scholarly journals Rutin trihydrate attenuated cisplatin- induced cardiac toxicity in isolated perfused rat’s hearts

2020 ◽  
Author(s):  
Ishfaq Bukhari ◽  
Osama Yousif Mohamed ◽  
Rahmathunnisa Lateef ◽  
Sabiha Fatima ◽  
Fahim Vohra ◽  
...  
Keyword(s):  
Mechanical Performance ◽  
Left Ventricular ◽  
Dependent Manner ◽  
Protective Effects ◽  
Time Index ◽  
Pressure Time ◽  
Rat Hearts ◽  
Perfused Rat Hearts ◽  
Dose Dependent ◽  
Isolated Perfused Rat Hearts

Abstract Background The present study aims to investigate the protective effect of rutin against cisplatin induced toxic effects on the mechanical performance of the myocardium, histopathology, and oxidative stress in isolated perfused rat hearts. Methods Cardiotoxicity of cisplatin was assessed at three dosage levels (1, 7, and 14 mg/l) in the isolated perfused rat hearts. The toxic effect of cisplarin was assessed on left ventricular pressure (LVP), heart rate (HR), dp/dt(max), dp/dt (min), perfusion pressure, pressure-time index, contractility index and duration of diastole. Measurements were carried out one minute before perfusion of cisplatin and 60 minutes after perfusion. Results Cisplatin reduced significantly (p < 0.05) in a dose-dependent manner LVP, dp/dt(max), dp/dt(min) and pressure- time index. Perfusion of rutin trihydrate (1 µM/l), 10 minutes before administration of cisplatin and throughout the experiment significantly (p < 0.05) attenuated the detrimental effects of cisplatin on cardiac parameters. Cisplatin caused degeneration and necrosis of cardiac muscle cells, while rutin reduced these changes and restored normal heart histology. Moreover, cisplatin reduced the myocardium concentration of reduced glutathione and increased the level of malondialdehyde, whereas rutin almost reversed these changes. Conclusion Cisplatin-induced dose-dependent impairment of several parameters of cardiac function and produced histopathological alterations in isolated rat hearts. These harmful effects of cisplatin were ameliorated by rutin trihydrate. These findings suggest the potential protective effects of rutin trihydrate against cisplatin-induced cardiotoxicity.

scholarly journals Wastes from Agricultural Silage Film Recycling Line as a Potential Polymer Materials

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1383
Author(s):  
Jerzy Korol ◽  
Aleksander Hejna ◽  
Klaudiusz Wypiór ◽  
Krzysztof Mijalski ◽  
Ewelina Chmielnicka
Keyword(s):  
Vinyl Acetate ◽  
Thermal Performance ◽  
Mechanical Performance ◽  
Ethylene Vinyl Acetate ◽  
Tensile Tests ◽  
Solid Particles ◽  
Polymer Materials ◽  
Slight Reduction ◽  
Scanning Calorimetry ◽  
Crystallinity Degree

The recycling of plastics is currently one of the most significant industrial challenges. Due to the enormous amounts of plastic wastes generated by various industry branches, it is essential to look for potential methods for their utilization. In the presented work, we investigated the recycling potential of wastes originated from the agricultural films recycling line. Their structure and properties were analyzed, and they were modified with 2.5 wt % of commercially available compatibilizers. The mechanical and thermal performance of modified wastes were evaluated by tensile tests, thermogravimetric analysis, and differential scanning calorimetry. It was found that incorporation of such a small amount of modifiers may overcome the drawbacks caused by the presence of impurities. The incorporation of maleic anhydride-grafted compounds enhanced the tensile strength of wastes by 13–25%. The use of more ductile compatibilizers—ethylene-vinyl acetate and paraffin increased the elongation at break by 55–64%. The presence of compatibilizers also reduced the stiffness of materials resulting from the presence of solid particles. It was particularly emphasized for styrene-ethylene-butadiene-styrene and ethylene-vinyl acetate copolymers, which caused up to a 20% drop of Young’s modulus. Such effects may facilitate the further applications of analyzed wastes, e.g., in polymer film production. Thermal performance was only slightly affected by compatibilization. It caused a slight reduction in polyethylene melting temperatures (up to 2.8 °C) and crystallinity degree (up to 16%). For more contaminated materials, the addition of compatibilizers caused a minor reduction in the decomposition onset (up to 6 °C). At the same time, for the waste after three washing cycles, thermal stability was improved. Moreover, depending on the desired properties and application, materials do not have to go through the whole recycling line, simplifying the process, reducing energy and water consumption. The presented results indicate that it is possible to efficiently use the materials, which do not have to undergo the whole recycling process. Despite the presence of impurities, they could be applied in the manufacturing of products which do not require exceptional mechanical performance.

scholarly journals Design and Characterization of Microscale Auxetic and Anisotropic Structures Fabricated by Multiphoton Lithography

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 446
Author(s):  
Ioannis Spanos ◽  
Zacharias Vangelatos ◽  
Costas Grigoropoulos ◽  
Maria Farsari
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Mechanical Performance ◽  
Element Analysis ◽  
Mechanical Responses ◽  
Multiphoton Lithography ◽  
Anisotropic Structures ◽  
Scanning Electron

The need for control of the elastic properties of architected materials has been accentuated due to the advances in modelling and characterization. Among the plethora of unconventional mechanical responses, controlled anisotropy and auxeticity have been promulgated as a new avenue in bioengineering applications. This paper aims to delineate the mechanical performance of characteristic auxetic and anisotropic designs fabricated by multiphoton lithography. Through finite element analysis the distinct responses of representative topologies are conveyed. In addition, nanoindentation experiments observed in-situ through scanning electron microscopy enable the validation of the modeling and the observation of the anisotropic or auxetic phenomena. Our results herald how these categories of architected materials can be investigated at the microscale.

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