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Rødland L, Rønning L, Kildal AB, How OJ. The β 3 Adrenergic Receptor Antagonist L-748,337 Attenuates Dobutamine-Induced Cardiac Inefficiency While Preserving Inotropy in Anesthetized Pigs. J Cardiovasc Pharmacol Ther 2021; 26:714-723. [PMID: 34551626 PMCID: PMC8547236 DOI: 10.1177/10742484211048762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Excessive myocardial oxygen consumption (MVO2) is considered a limitation for catecholamines, termed oxygen cost of contractility. We hypothesize that increased MVO2 induced by dobutamine is not directly related to contractility but linked to intermediary myocardial metabolism. Furthermore, we hypothesize that selective β3 adrenergic receptor (β3AR) antagonism using L-748,337 prevents this. In an open-chest pig model, using general anesthesia, we assessed cardiac energetics, hemodynamics and arterial metabolic substrate levels at baseline, ½ hour and 6 hours after onset of drug infusion. Cardiac efficiency was assessed by relating MVO2 to left ventricular work (PVA; pressure–volume area). Three groups received dobutamine (5 μg/kg/min), dobutamine + L-748,337 (bolus 50 μg/kg), or saline for time-matched controls. Cardiac efficiency was impaired over time with dobutamine infusion, displayed by persistently increased unloaded MVO2 from ½ hour and 47% increase in the slope of the PVA–MVO2 relation after 6 hours. Contractility increased immediately with dobutamine infusion (dP/dtmax; 1636 ± 478 vs 2888 ± 818 mmHg/s, P < 0.05) and persisted throughout the protocol (2864 ± 1055 mmHg/s, P < 0.05). Arterial free fatty acid increased gradually (0.22 ± 0.13 vs 0.39 ± 0.30 mM, P < 0.05) with peak levels after 6 hours (1.1 ± 0.4 mM, P < 0.05). By combining dobutamine with L-748,337 the progressive impairment in cardiac efficiency was attenuated. Interestingly, this combined treatment effect occurred despite similar alterations in cardiac inotropy and substrate supply. We conclude that the extent of cardiac inefficiency following adrenergic stimulation is dependent on the duration of drug infusion, and β3AR blockade may attenuate this effect.
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Affiliation(s)
- Lars Rødland
- Cardiovascular Research Group, Institute of Medical Biology, Faculty of Health Sciences, 8016UiT-The Arctic University of Norway, Tromsø, Norway
| | - Leif Rønning
- Cardiovascular Research Group, Institute of Medical Biology, Faculty of Health Sciences, 8016UiT-The Arctic University of Norway, Tromsø, Norway
| | - Anders Benjamin Kildal
- Department of Anesthesiology and Intensive Care, 60519University Hospital of North Norway, Tromsø, Norway
| | - Ole-Jakob How
- Cardiovascular Research Group, Institute of Medical Biology, Faculty of Health Sciences, 8016UiT-The Arctic University of Norway, Tromsø, Norway
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Lund J, Hafstad AD, Boardman NT, Rossvoll L, Rolim NP, Ahmed MS, Florholmen G, Attramadal H, Wisløff U, Larsen TS, Aasum E. Exercise training promotes cardioprotection through oxygen-sparing action in high fat-fed mice. Am J Physiol Heart Circ Physiol 2015; 308:H823-9. [PMID: 25637547 DOI: 10.1152/ajpheart.00734.2014] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Accepted: 01/28/2015] [Indexed: 11/22/2022]
Abstract
Although exercise training has been demonstrated to have beneficial cardiovascular effects in diabetes, the effect of exercise training on hearts from obese/diabetic models is unclear. In the present study, mice were fed a high-fat diet, which led to obesity, reduced aerobic capacity, development of mild diastolic dysfunction, and impaired glucose tolerance. Following 8 wk on high-fat diet, mice were assigned to 5 weekly high-intensity interval training (HIT) sessions (10 × 4 min at 85-90% of maximum oxygen uptake) or remained sedentary for the next 10 constitutive weeks. HIT increased maximum oxygen uptake by 13%, reduced body weight by 16%, and improved systemic glucose homeostasis. Exercise training was found to normalize diastolic function, attenuate diet-induced changes in myocardial substrate utilization, and dampen cardiac reactive oxygen species content and fibrosis. These changes were accompanied by normalization of obesity-related impairment of mechanical efficiency due to a decrease in work-independent myocardial oxygen consumption. Finally, we found HIT to reduce infarct size by 47% in ex vivo hearts subjected to ischemia-reperfusion. This study therefore demonstrated for the first time that exercise training mediates cardioprotection following ischemia in diet-induced obese mice and that this was associated with oxygen-sparing effects. These findings highlight the importance of optimal myocardial energetics during ischemic stress.
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Affiliation(s)
- J Lund
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, Norway;
| | - A D Hafstad
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, Norway
| | - N T Boardman
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, Norway
| | - L Rossvoll
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, Norway
| | - N P Rolim
- K. G. Jebsen Center of Exercise in Medicine, Department of Circulation and Medical Imaging, Faculty of Medicine, Norwegian University of Science and Technology and Saint Olavs Hospital, Trondheim University Hospital, Trondheim, Norway; and
| | - M S Ahmed
- Institute for Surgical Research, Department of Cardiology, Center for Heart Failure Research, Oslo University Hospital-Rikshospitalet, University of Oslo, Oslo, Norway
| | - G Florholmen
- Institute for Surgical Research, Department of Cardiology, Center for Heart Failure Research, Oslo University Hospital-Rikshospitalet, University of Oslo, Oslo, Norway
| | - H Attramadal
- Institute for Surgical Research, Department of Cardiology, Center for Heart Failure Research, Oslo University Hospital-Rikshospitalet, University of Oslo, Oslo, Norway
| | - U Wisløff
- K. G. Jebsen Center of Exercise in Medicine, Department of Circulation and Medical Imaging, Faculty of Medicine, Norwegian University of Science and Technology and Saint Olavs Hospital, Trondheim University Hospital, Trondheim, Norway; and
| | - T S Larsen
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, Norway
| | - E Aasum
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, Norway
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Ito M, Jaswal JS, Lam VH, Oka T, Zhang L, Beker DL, Lopaschuk GD, Rebeyka IM. High levels of fatty acids increase contractile function of neonatal rabbit hearts during reperfusion following ischemia. Am J Physiol Heart Circ Physiol 2010; 298:H1426-37. [DOI: 10.1152/ajpheart.00284.2009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In the neonatal heart the transition from using carbohydrates to using fatty acids has not fully matured and oxidative metabolism/ATP generation may be limiting contractile function after ischemia. This study tested the hypothesis that increasing fatty acid availability increases recovery of left ventricular (LV) work by increasing palmitate oxidation, tricarboxylic acid (TCA) cycle activity, and ATP generation. Isolated working hearts from 7-day-old rabbits were perfused with Krebs solution containing low (0.4 mM) or high (2.4 mM) palmitate and 5.5 mM glucose. Hearts were subjected to 35-min global ischemia before 40-min reperfusion, and rates of glycolysis, glucose oxidation, and palmitate oxidation were assessed. LV work was similar before ischemia but was greater during reperfusion in hearts perfused with 2.4 mM palmitate compared with hearts perfused with 0.4 mM palmitate [6.98 ± 0.14 ( n = 15) vs. 3.01 ± 0.23 ( n = 16) mJ·beat−1·g dry wt−1; P < 0.05]. This was accompanied by increased LV energy expenditure during reperfusion [35.98 ± 0.16 ( n = 8) vs. 19.92 ± 0.18 ( n = 6) mJ·beat−1·g dry wt−1; P < 0.05]. During reperfusion the rates of palmitate oxidation [237.5 ± 28.10 ( n = 7) vs. 86.0 ± 9.7 ( n = 6) nmol·g dry wt−1·min−1; P < 0.05], total TCA cycle activity [2.65 ± 0.39 ( n = 7) vs. 1.36 ± 0.14 ( n = 6) μmol acetyl-CoA·g dry wt−1·min−1; P < 0.05], and ATP generation attributable to palmitate oxidation [26.6 ± 3.1 ( n = 7) vs. 12.6 ± 1.7 ( n = 6) μmol·g dry wt−1·min−1; P < 0.05] were greater in hearts perfused with 2.4 mM palmitate. These data indicate that the neonatal heart has decreased energy reserve, and, in contrast to the mature heart, increasing availability of fatty acid substrate increases energy production and improves recovery of function after ischemia.
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Affiliation(s)
- Masayoshi Ito
- Mazankowski Alberta Heart Institute, Departments of 1Pediatrics and
| | - Jagdip S. Jaswal
- Mazankowski Alberta Heart Institute, Departments of 1Pediatrics and
- Pharmacology and
| | - Victoria H. Lam
- Mazankowski Alberta Heart Institute, Departments of 1Pediatrics and
| | - Tatsujiro Oka
- Mazankowski Alberta Heart Institute, Departments of 1Pediatrics and
| | - Liyan Zhang
- Mazankowski Alberta Heart Institute, Departments of 1Pediatrics and
- Pharmacology and
| | - Donna L. Beker
- Mazankowski Alberta Heart Institute, Departments of 1Pediatrics and
- Division of Cardiac Surgery, University of Alberta, Edmonton, Alberta, Canada
| | - Gary D. Lopaschuk
- Mazankowski Alberta Heart Institute, Departments of 1Pediatrics and
- Pharmacology and
| | - Ivan M. Rebeyka
- Mazankowski Alberta Heart Institute, Departments of 1Pediatrics and
- Division of Cardiac Surgery, University of Alberta, Edmonton, Alberta, Canada
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Feng HZ, Jin JP. Coexistence of cardiac troponin T variants reduces heart efficiency. Am J Physiol Heart Circ Physiol 2010; 299:H97-H105. [PMID: 20418479 DOI: 10.1152/ajpheart.01105.2009] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Corresponding to the synchronized contraction of the myocardium and rhythmic pumping function of the heart, a single form of cardiac troponin T (cTnT) is present in the adult cardiac muscle of humans and most other vertebrate species. Alternative splicing variants of cTnT are found in failing human hearts and animal dilated cardiomyopathies. Biochemical analyses have shown that these cTnT variants are functional and produce shifted myofilament Ca(2+) sensitivity. We proposed a hypothesis that the coexistence of two or more functionally distinct TnT variants in the adult ventricular muscle that is normally activated as a syncytium may decrease heart function and cause cardiomyopathy (Huang et al., Am J Physiol Cell Physiol 294: C213-C222, 2008). In the present study, we studied transgenic mouse hearts expressing one or two cTnT variants in addition to normal adult cTnT to investigate whether desynchronized myofilament activation decreases ventricular efficiency. The function of ex vivo working hearts was examined in the absence of systemic neurohumoral influence. The results showed that the transgenic mouse hearts produced lower maximum left ventricular pressure, slower contractile and relaxation velocities, and decreased stroke volume compared with wild-type controls. Ventricular pumping efficiency, calculated by the ejection integral versus total systolic integral and cardiac work versus oxygen consumption, was significantly lower in transgenic mouse hearts and corresponded to the number of cTnT variants present. The results indicated a pathogenic mechanism in which the coexistence of functionally different cTnT variants in cardiac muscle reduces myocardial efficiency due to desynchronized thin filament activation.
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Affiliation(s)
- Han-Zhong Feng
- Department of Physiology, Wayne State University School of Medicine, 540 E. Canfield, Detroit, MI 48201, USA
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