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Swoap SJ, Körtner G, Geiser F. Heart rate dynamics in a marsupial hibernator. J Exp Biol 2017; 220:2939-2946. [DOI: 10.1242/jeb.155879] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Accepted: 05/30/2017] [Indexed: 11/20/2022]
Abstract
The eastern pygmy-possum (Cercartetus nanus) is a small marsupial that can express spontaneous short bouts of torpor, as well as multi-day bouts of deep hibernation. To examine heart rate (HR) control at various stages of torpor in a marsupial hibernator, and to see whether HR variability differs from deep placental hibernators, we used radiotelemetry to measure ECG and Tb while measuring the rate of O2 consumption and ventilation. The HR and rate of O2 consumption during euthermia was at its minimum (321±34 bpm, 0.705±0.048 ml O2/g*h) at an ambient temperature (Ta) of 31°C. HR had an inverse linear relationship with Ta to a maximum of 630±19 bpm at a Ta of 20°C. During entry into torpor at an Ta of 20°C, HR slowed primarily as a result of episodic periods of cardiac activity where electrical activity of the heart occurred in groups of 3 or 4 heart beats. When Tb was stable at 24°C in these torpor bouts, the episodic nature of HR had disappeared (i.e. no asystoles) with a rate of 34±3 bpm. For multi-day bouts of deep torpor, Ta was lowered to 6.6±0.8°C. During these deep bouts of torpor, Tb reached a minimum of 8.0±1.0°C, with a minimum HR of 8 bpm and a minimum rate of O2 consumption of 0.029±0.07 ml O2/g*h. Shivering bouts occurred in deep torpor about every 8 minutes, during which ventilation occurred, and HR was elevated to 40 bpm. The duration of the QRS complex increased from 12ms during euthermia to 69 ms at a Tb of 8°C. These findings demonstrate the dynamic functioning range of heart rate to be about 600 bpm (∼80 fold), one of the largest known ranges in mammals. Our study shows that despite a separation of ∼160 million years the control and function of the cardiac system seems indistinguishable in marsupial and placental hibernating mammals.
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Affiliation(s)
- Steven J. Swoap
- Department of Biology, Williams College, Williamstown, MA 01267, USA
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, Australia
| | - Gerhard Körtner
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, Australia
| | - Fritz Geiser
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, Australia
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Lujan HL, Rivers JP, DiCarlo SE. Complex and interacting influences of the autonomic nervous system on cardiac electrophysiology in conscious mice. Auton Neurosci 2016; 201:24-31. [PMID: 27594686 PMCID: PMC5108678 DOI: 10.1016/j.autneu.2016.08.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 08/15/2016] [Accepted: 08/28/2016] [Indexed: 01/09/2023]
Abstract
Mice may now be the preferred animal model for biomedical research due to its anatomical, physiological, and genetic similarity to humans. However, little is known about accentuated antagonism of chronotropic and dromotropic properties in conscious mice. Accordingly, we describe the complex and interacting influence of the autonomic nervous system on cardiac electrophysiology in conscious mice. Specifically, we report the effects of single and combined cardiac autonomic blockade on measurements of pulse interval (heart rate), atrio-ventricular interval, sinus node recovery time (SNRT), SNRT corrected for spontaneous sinus cycle, and Wenckebach cycle length in conscious mice free of the confounding influences of anesthetics and surgical trauma. Autonomic influences were quantified as the change in parameter induced by its selective blocker (Sympathetic or Parasympathetic Effect) or as the difference between the intrinsic value and the value after a selective blocker (Sympathetic or Parasympathetic Tonus). Sympatho-Vagal Balance (SVB) was assessed as the ratio of control interval to intrinsic interval. SVB suggests slight parasympathetic dominance in the control of cardiac electrophysiology intervals. Furthermore, results documents a complex interaction between the sympathetic and parasympathetic divisions of the autonomic nervous system in the control of cardiac electrophysiology parameters. Specifically, the parasympathetic effect was greater than the parasympathetic tonus in the control of cardiac electrophysiology parameters. In contrast, the sympathetic effect was smaller than the sympathetic tonus in the control of cardiac electrophysiology parameters. Results have important implications because actions of pharmacological agents that alter the autonomic control of cardiac electrophysiology are transformed by these interacting mechanisms.
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Affiliation(s)
- Heidi L Lujan
- Wayne State University School of Medicine, Department of Physiology, 540 E. Canfield Ave, Detroit, MI 48201, USA.
| | - Joshua P Rivers
- Wayne State University School of Medicine, Department of Physiology, 540 E. Canfield Ave, Detroit, MI 48201, USA.
| | - Stephen E DiCarlo
- Wayne State University School of Medicine, Department of Physiology, 540 E. Canfield Ave, Detroit, MI 48201, USA.
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53
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Hylander BL, Repasky EA. Thermoneutrality, Mice, and Cancer: A Heated Opinion. Trends Cancer 2016; 2:166-175. [PMID: 28741570 DOI: 10.1016/j.trecan.2016.03.005] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 03/10/2016] [Accepted: 03/11/2016] [Indexed: 12/31/2022]
Abstract
The 'mild' cold stress caused by standard sub-thermoneutral housing temperatures used for laboratory mice in research institutes is sufficient to significantly bias conclusions drawn from murine models of several human diseases. We review the data leading to this conclusion, discuss the implications for research and suggest ways to reduce problems in reproducibility and experimental transparency caused by this housing variable. We have found that these cool temperatures suppress endogenous immune responses, skewing tumor growth data and the severity of graft versus host disease, and also increase the therapeutic resistance of tumors. Owing to the potential for ambient temperature to affect energy homeostasis as well as adrenergic stress, both of which could contribute to biased outcomes in murine cancer models, housing temperature should be reported in all publications and considered as a potential source of variability in results between laboratories. Researchers and regulatory agencies should work together to determine whether changes in housing parameters would enhance the use of mouse models in cancer research, as well as for other diseases. Finally, for many years agencies such as the National Cancer Institute (NCI) have encouraged the development of newer and more sophisticated mouse models for cancer research, but we believe that, without an appreciation of how basic murine physiology is affected by ambient temperature, even data from these models is likely to be compromised.
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Affiliation(s)
- Bonnie L Hylander
- Roswell Park Cancer Institute, Department of Immunology, Elm and Carlton Streets, Buffalo, NY 14263-0001, USA
| | - Elizabeth A Repasky
- Roswell Park Cancer Institute, Department of Immunology, Elm and Carlton Streets, Buffalo, NY 14263-0001, USA.
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54
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Gibbs VK, Smith DL. Nutrition and energetics in rodent longevity research. Exp Gerontol 2016; 86:90-96. [PMID: 27073168 DOI: 10.1016/j.exger.2016.04.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 03/30/2016] [Accepted: 04/04/2016] [Indexed: 12/25/2022]
Abstract
The impact of calorie amount on aging has been extensively described; however, variation over time and among laboratories in animal diet, housing condition, and strains complicates discerning the true influence of calories (energy) versus nutrients on lifespan. Within the dietary restriction field, single macronutrient manipulations have historically been researched as a means to reduce calories while maintaining adequate levels of essential nutrients. Recent reports of nutritional geometry, including rodent models, highlight the impact macronutrients have on whole organismal aging outcomes. However, other environmental factors (e.g., ambient temperature) may alter nutrient preferences and requirements revealing context specific outcomes. Herein we highlight factors that influence the energetic and nutrient demands of organisms which oftentimes have underappreciated impacts on clarifying interventional effects on health and longevity in aging studies and subsequent translation to improve the human condition.
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Affiliation(s)
- Victoria K Gibbs
- Department of Nutrition Sciences, University of Alabama at Birmingham, Birmingham, AL 35294, USA; Nathan Shock Center of Excellence in the Basic Biology of Aging, University of Alabama at Birmingham, Birmingham, AL 35294, USA; Comprehensive Center for Healthy Aging, University of Alabama at Birmingham, Birmingham, AL 35294, USA; Nutrition Obesity Research Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Daniel L Smith
- Department of Nutrition Sciences, University of Alabama at Birmingham, Birmingham, AL 35294, USA; Nathan Shock Center of Excellence in the Basic Biology of Aging, University of Alabama at Birmingham, Birmingham, AL 35294, USA; Comprehensive Center for Healthy Aging, University of Alabama at Birmingham, Birmingham, AL 35294, USA; Nutrition Obesity Research Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
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55
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Dzenda T, Ayo JO, Sinkalu VO, Yaqub LS. Diurnal, seasonal, and sex patterns of heart rate in grip-restrained African giant rats (Cricetomys gambianus, Waterhouse). Physiol Rep 2015; 3:e12581. [PMID: 26471756 PMCID: PMC4632951 DOI: 10.14814/phy2.12581] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 09/09/2015] [Accepted: 09/12/2015] [Indexed: 11/24/2022] Open
Abstract
This study was carried out to determine heart rate (HR) values, including diurnal, seasonal, and sex patterns, in the African giant rat (Cricetomys gambianus, Waterhouse). HR was measured using stethoscope in grip-restrained African giant rats of either sex (103 bucks and 98 does), live-trapped from a tropical Savannah, and caged individually in the laboratory during the harmattan (cold-dry), hot-dry, and rainy seasons over a 3-year period. The HR fluctuated between 90 and 210 beats per minute (bpm) throughout the study period. Diurnal changes in HR (mean ± SEM) during the hot-dry and rainy seasons were nonsignificant (P > 0.05), but the morning and afternoon values differed (P < 0.01) during the cold-dry season. The HR varied (P < 0.05) among seasons, with peak, nadir, and moderate values recorded during the cold-dry (165.8 ± 0.51 bpm), hot-dry (153.1 ± 0.74 bpm), and rainy (163.4 ± 0.70 bpm) seasons, respectively. Mean HR of bucks was lower than that of does during the cold-dry (P < 0.0001) and hot-dry (P < 0.01) seasons, but sex difference during the rainy season was insignificant (P > 0.05). Overall, mean HR was lower (P < 0.0001) in bucks (158.8 ± 0.53 bpm) than in does (164.8 ± 0.53 bpm). In conclusion, values of HR in African giant rats are shown for the first time. Season, sex, and daytime influenced the HR, and should be considered during clinical evaluations of the rats.
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Affiliation(s)
- Tavershima Dzenda
- Department of Veterinary Physiology, Ahmadu Bello University, Zaria, Nigeria
| | - Joseph O Ayo
- Department of Veterinary Physiology, Ahmadu Bello University, Zaria, Nigeria
| | - Victor O Sinkalu
- Department of Veterinary Physiology, Ahmadu Bello University, Zaria, Nigeria
| | - Lukuman S Yaqub
- Department of Veterinary Physiology, Ahmadu Bello University, Zaria, Nigeria
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56
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Maloney SK, Fuller A, Mitchell D, Gordon C, Overton JM. Translating animal model research: does it matter that our rodents are cold? Physiology (Bethesda) 2015; 29:413-20. [PMID: 25362635 DOI: 10.1152/physiol.00029.2014] [Citation(s) in RCA: 107] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Does it matter that rodents used as preclinical models of human biology are routinely housed below their thermoneutral zone? We compile evidence showing that such rodents are cold-stressed, hypermetabolic, hypertensive, sleep-deprived, obesity-resistant, fever-resistant, aging-resistant, and tumor-prone compared with mice housed at thermoneutrality. The same genotype of mouse has a very different phenotype and response to physiological or pharmacological intervention when raised below or at thermoneutrality.
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Affiliation(s)
- Shane K Maloney
- School of Anatomy Physiology and Human Biology, The University of Western Australia, Stirling Highway, Crawley, Australia; Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Parktown, South Africa
| | - Andrea Fuller
- Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Parktown, South Africa
| | - Duncan Mitchell
- School of Anatomy Physiology and Human Biology, The University of Western Australia, Stirling Highway, Crawley, Australia; Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Parktown, South Africa
| | - Christopher Gordon
- Toxicity Assessment Division, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina; and
| | - J Michael Overton
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida
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57
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Belcher SM, Gear RB, Kendig EL. Bisphenol A alters autonomic tone and extracellular matrix structure and induces sex-specific effects on cardiovascular function in male and female CD-1 mice. Endocrinology 2015; 156:882-95. [PMID: 25594700 PMCID: PMC4330319 DOI: 10.1210/en.2014-1847] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The aim of this study was to determine whether bisphenol A (BPA) has adverse effects on cardiovascular functions in CD-1 mice and define sex-specific modes of BPA action in the heart. Dams and analyzed progeny were maintained on a defined diet containing BPA (0.03, 0.3, 3, 30, or 300 ppm) that resulted in BPA exposures from 4-5 to approximately 5000 μg/kg · d or a diet containing 17α-ethinyl estradiol (EE; ∼0.02, 0.2, and 0.15 μg/kg · d) as an oral bioavailable estrogen control. Assessment of electrocardiogram parameters using noninvasive methods found that ventricular functions in both male and female mice were not altered by either BPA or EE. However, exposure-related changes in the rates of ventricular contraction, suggestive of a shift in sympathovagal balance of heart rate control toward increased parasympathetic activity, were detected in males. Decreased systolic blood pressure was observed in males exposed to BPA above 5 μg/kg · d and in females from the highest BPA exposure group. Morphometric histological measures revealed sexually dimorphic changes in the composition of the cardiac collagen extracellular matrix, increases in fibrosis, and evidence of modest exposure-related remodeling. Experiments using the α-selective adrenergic agonist phenylephrine found that BPA enhanced reflex bradycardia in females, but not males, revealed that BPA and EE exposure sex specifically altered the sympathetic regulation of the baroreflex circuits. Increased sensitivity to the cardiotoxic effects of the β-adrenergic agonist isoproterenol was observed in BPA- and EE-exposed females. This effect was not observed in males, in which BPA or EE exposures were protective of isoproterenol-induced ischemic damage and hypertrophy. The results of RNA sequence analysis identified significant sex-specific changes in gene expression in response to BPA that were consistent with the observed exposure-related phenotypic changes in the collagenous and noncollagenous extracellular matrix, cardiac remodeling, altered autonomic responses, changes in ion channel and transporter functions, and altered glycolytic and lipid metabolism.
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Affiliation(s)
- Scott M Belcher
- Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267-0575
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58
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Abstract
Environmental temperature can have a surprising impact on extremity growth in homeotherms, but the underlying mechanisms have remained elusive for over a century. Limbs of animals raised at warm ambient temperature are significantly and permanently longer than those of littermates housed at cooler temperature. These remarkably consistent lab results closely resemble the ecogeographical tenet described by Allen's "extremity size rule," that appendage length correlates with temperature and latitude. This phenotypic growth plasticity could have adaptive significance for thermal physiology. Shortened extremities help retain body heat in cold environments by decreasing surface area for potential heat loss. Homeotherms have evolved complex mechanisms to maintain tightly regulated internal temperatures in challenging environments, including "facultative extremity heterothermy" in which limb temperatures can parallel ambient. Environmental modulation of tissue temperature can have direct and immediate consequences on cell proliferation, metabolism, matrix production, and mineralization in cartilage. Temperature can also indirectly influence cartilage growth by modulating circulating levels and delivery routes of essential hormones and paracrine regulators. Using an integrated approach, this article synthesizes classic studies with new data that shed light on the basis and significance of this enigmatic growth phenomenon and its relevance for treating human bone elongation disorders. Discussion centers on the vasculature as a gateway to understanding the complex interconnection between direct (local) and indirect (systemic) mechanisms of temperature-enhanced bone lengthening. Recent advances in imaging modalities that enable the dynamic study of cartilage growth plates in vivo will be key to elucidating fundamental physiological mechanisms of long bone growth regulation.
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Affiliation(s)
- Maria A Serrat
- Department of Anatomy and Pathology, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia
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59
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Kurtz TW, Lujan HL, DiCarlo SE. The 24 h pattern of arterial pressure in mice is determined mainly by heart rate-driven variation in cardiac output. Physiol Rep 2014; 2:2/11/e12223. [PMID: 25428952 PMCID: PMC4255824 DOI: 10.14814/phy2.12223] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Few studies have systematically investigated whether daily patterns of arterial blood pressure over 24 h are mediated by changes in cardiac output, peripheral resistance, or both. Understanding the hemodynamic mechanisms that determine the 24 h patterns of blood pressure may lead to a better understanding of how such patterns become disturbed in hypertension and influence risk for cardiovascular events. In conscious, unrestrained C57BL/6J mice, we investigated whether the 24 h pattern of arterial blood pressure is determined by variation in cardiac output, systemic vascular resistance, or both and also whether variations in cardiac output are mediated by variations in heart rate and or stroke volume. As expected, arterial pressure and locomotor activity were significantly (P < 0.05) higher during the nighttime period compared with the daytime period when mice are typically sleeping (+12.5 ± 1.0 mmHg, [13%] and +7.7 ± 1.3 activity counts, [254%], respectively). The higher arterial pressure during the nighttime period was mediated by higher cardiac output (+2.6 ± 0.3 mL/min, [26%], P < 0.05) in association with lower peripheral resistance (-1.5 ± 0.3 mmHg/mL/min, [-13%] P < 0.05). The increased cardiac output during the nighttime was mainly mediated by increased heart rate (+80.0 ± 16.5 beats/min, [18%] P < 0.05), as stroke volume increased minimally at night (+1.6 ± 0.5 μL per beat, [6%] P < 0.05). These results indicate that in C57BL/6J mice, the 24 h pattern of blood pressure is hemodynamically mediated primarily by the 24 h pattern of cardiac output which is almost entirely determined by the 24 h pattern of heart rate. These findings suggest that the differences in blood pressure between nighttime and daytime are mainly driven by differences in heart rate which are strongly correlated with differences in locomotor activity.
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Affiliation(s)
- Theodore W Kurtz
- Department of Laboratory Medicine, University of California, San Francisco, San Francisco, California
| | - Heidi L Lujan
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Stephen E DiCarlo
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
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60
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Sex Differences in Physiological Acclimatization after Transfer in Wistar Rats. Animals (Basel) 2014; 4:693-711. [PMID: 26479007 PMCID: PMC4494431 DOI: 10.3390/ani4040693] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 10/16/2014] [Accepted: 10/22/2014] [Indexed: 11/22/2022] Open
Abstract
Simple Summary This study in laboratory rodents shows a sex specific effect of breeder to research facility transfer on several physiological parameters, such as heart rate and blood pressure. We recommend at least 8 days of acclimatization time after transfer in male rats and at least two weeks in female rats, before using these animals in research. Abstract Most laboratory animals used in research are vendor-bred and transferred to research facilities. Transfer procedures might have considerable and unintended effects on research results. In the present study we compared physiological and behavioral parameters before and after external and internal transfer, as well as between transferred and non-transferred Wistar rats. The impact of both external and internal transfer on body weight, plasma corticosterone levels, heart rate, blood pressure, and locomotor activity was studied in both male and female Wistar rats, taking into account the sex differences in stress responsivity. External transfer was found to decrease body weight, increase plasma corticosterone, increase activity, increase heart rate in female rats, but decrease heart rate in male rats. Parameters showed differences between the sexes and light phases. This study shows that acclimatization after transfer is sex-specific and researchers should take the sex into consideration when determining the acclimatization period. It is recommended to allow for acclimatization of at least 8 days in males and two weeks in females after external transfer and timely (2 days before starting experiments) transfer the animals internally to the testing room.
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61
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Thetkathuek A, Yingratanasuk T, Jaidee W, Ekburanawat W. Cold exposure and health effects among frozen food processing workers in eastern Thailand. Saf Health Work 2014; 6:56-61. [PMID: 25830071 PMCID: PMC4371894 DOI: 10.1016/j.shaw.2014.10.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 09/08/2014] [Accepted: 10/03/2014] [Indexed: 11/20/2022] Open
Abstract
Frozen food processing workers work under a cold environment which can cause several adverse health effects.This study explored factors affecting workers' health in the frozen food industry in Thailand. Participants comprised 497 workers exposed to a cold working environment and 255 office workers who served as the controls. Data were collected by a survey on the work environment, and the interview of workers for abnormal symptoms. The exposed group had the following characteristics: 52.7% male, overall average age of 27 (SD 6.6) years old, attained elementary education (Grade 4 and Grade 6) (54.1%), married (48.9%), smokers (21.3%), alcohol consumption (31.0%), duration of work was between 1 and 5 years (65.2%), working 6 days a week (82.7%), 1–5 hours of overtime per week (33.8%), office workers (33.9%); work category: sizing (6.9%), peeling (28.3%) dissecting (22.2%), and in the warehouse (8.6%). The temperature in the work environment ranged from 17.2°C to 19.2°C in most sections, −18.0°C in the warehouse, and 25°C in the office areas. Warehouse workers had more abnormal symptoms than controls including repeated pain in the musculoskeletal system (OR 11.9; 95% CI 6.12–23.45), disturbance throughout the body (OR 4.60; 95% CI 2.00–10.56), respiratory symptoms (OR 9.73; 95% CI 3.53–26.80), episodic finger symptoms (OR 13.51; 95% CI 5.17–35.33). The study results suggest that workers' health should be monitored especially with regard to back and muscle pain, respiratory symptoms, episodic finger symptoms, and cardiovascular symptoms. Health promotion campaigns such as antismoking and reduction of alcohol consumption should be established because smoking and alcohol consumption are contributing factors to the pathogenesis of Raynaud's phenomenon and peripheral vascular disorders such as hypertension and heart disease.
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Affiliation(s)
- Anamai Thetkathuek
- Department of Industrial Hygiene and Safety, Faculty of Public Health, Burapha University, Chonburi, Thailand
| | - Tanongsak Yingratanasuk
- Department of Industrial Hygiene and Safety, Faculty of Public Health, Burapha University, Chonburi, Thailand
| | - Wanlop Jaidee
- Department of Public Health Foundations, Faculty of Public Health, Burapha University, Chonburi, Thailand
| | - Wiwat Ekburanawat
- Occupational Medicine Center, Samitivej Sriracha Hospital, Chonburi, Thailand
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62
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Pereda D, Pardo MR, Morales Y, Dominguez N, Arnau MR, Borges R. Mice lacking chromogranins exhibit increased aggressive and depression-like behaviour. Behav Brain Res 2014; 278:98-106. [PMID: 25257107 DOI: 10.1016/j.bbr.2014.09.022] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 09/10/2014] [Accepted: 09/15/2014] [Indexed: 12/14/2022]
Abstract
Chromogranins are acidic proteins; both chromogranins A and B constitute the main protein component in the vesicular matrix of large dense core vesicles. Chromogranins are a natural source of peptides with different physiological activities that have been associated with vascular and neurological diseases. We have used three different genetic mutant models of mice lacking chromogranin A, chromogranin B and both all on the same C57BL/6J background, to characterize the physiological roles of these proteins using metabolic, cardiovascular and behavioural tests. In mice from 3 to 18 months of age, the lack of any chromogranin promoted age-dependent hypersensitivity to insulin, while the lack of both chromogranins provoked progressive lack of response to stress, as restriction did not promote tachycardia in old mice. Moreover, the lack of chromogranin B produced a depressive-like and aggressive phenotype, while the lack either or both chromogranins increased barbering behaviour. In addition, we observed no effects on light-dark box or RotaRod tests. Mice lacking chromogranin B exhibited lower exploratory activity. Based on this extensive phenotyping with more than 2800 mice, these findings support roles of chromogranins, or the peptides derived from them, in the control of aggressive behaviour along with changes in their metabolic profile beyond their previously described activities in the secretory pathway.
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Affiliation(s)
- Daniel Pereda
- Pharmacology Unit, Medical School, University of La Laguna, Tenerife, Spain
| | - Marta R Pardo
- Pharmacology Unit, Medical School, University of La Laguna, Tenerife, Spain
| | - Yezer Morales
- Pharmacology Unit, Medical School, University of La Laguna, Tenerife, Spain
| | - Natalia Dominguez
- Pharmacology Unit, Medical School, University of La Laguna, Tenerife, Spain
| | - Maria Rosa Arnau
- Pharmacology Unit, Medical School, University of La Laguna, Tenerife, Spain
| | - Ricardo Borges
- Pharmacology Unit, Medical School, University of La Laguna, Tenerife, Spain.
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63
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Lujan HL, DiCarlo SE. Reperfusion-induced sustained ventricular tachycardia, leading to ventricular fibrillation, in chronically instrumented, intact, conscious mice. Physiol Rep 2014; 2:2/6/e12057. [PMID: 24973331 PMCID: PMC4208649 DOI: 10.14814/phy2.12057] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Reperfusion‐induced lethal ventricular arrhythmias are observed during relief of coronary artery spasm, with unstable angina, exercise‐induced ischemia, and silent ischemia. Accordingly, significant efforts are underway to understand the mechanisms responsible for reperfusion‐induced lethal arrhythmias and mice have become increasingly important in these efforts. However, although reperfusion‐induced sustained ventricular tachycardia leading to ventricular fibrillation (VF) has been recorded in many models, reports in mice are sparse and of limited success. Importantly, none of these studies were conducted in intact, conscious mice. Accordingly, a chronically instrumented, intact, conscious murine model of reperfusion‐induced lethal arrhythmias has the potential to be of major importance for advancing the concepts and methods that drive cardiovascular therapies. Therefore, we describe, for the first time, the use of an intact, conscious, murine model of reperfusion‐induced lethal arrhythmias. Male mice (n = 9) were instrumented to record cardiac output and the electrocardiogram. In addition, a snare was placed around the left main coronary artery. Following recovery, the susceptibility to sustained ventricular tachycardia produced by 3 min of occlusion and reperfusion of the left main coronary artery was determined in conscious mice by pulling on the snare. Reperfusion culminated in sustained ventricular tachycardia, leading to VF, in all nine conscious mice. The procedures conducted in conscious C57BL/6J mice, a strain commonly used in transgenic studies, can be utilized in genetically modified models to enhance our understanding of single gene defects on reperfusion‐induced lethal ventricular arrhythmias in intact, conscious, and complex animals. We describe, for the first time, the use of an intact, conscious, murine model of reperfusion‐induced lethal arrhythmias. This model has the potential to be of major importance for advancing the concepts and methods that drive antiarrhythmic therapies.
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Affiliation(s)
- Heidi L Lujan
- Department of Physiology, Wayne State University School of Medicine, Detroit, 48201, Michigan
| | - Stephen E DiCarlo
- Department of Physiology, Wayne State University School of Medicine, Detroit, 48201, Michigan
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64
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In-depth metabolic phenotyping of genetically engineered mouse models in obesity and diabetes. Mamm Genome 2014; 25:508-21. [PMID: 24792749 DOI: 10.1007/s00335-014-9520-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Accepted: 04/10/2014] [Indexed: 01/09/2023]
Abstract
The world-wide prevalence of obesity and diabetes has increased sharply during the last two decades. Accordingly, the metabolic phenotyping of genetically engineered mouse models is critical for evaluating the functional roles of target genes in obesity and diabetes, and for developing new therapeutic targets. In this review, we discuss the practical meaning of metabolic phenotyping, the strategy of choosing appropriate tests, and considerations when designing and performing metabolic phenotyping in mice.
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Ayo JO, Dzenda T, Olaifa F, Ake SA, Sani I. Diurnal and seasonal fluctuations in rectal temperature, respiration and heart rate of pack donkeys in a tropical savannah zone. J Equine Sci 2014; 25:1-6. [PMID: 24834007 PMCID: PMC4019199 DOI: 10.1294/jes.25.1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Accepted: 12/04/2013] [Indexed: 11/03/2022] Open
Abstract
The study was designed to determine diurnal and seasonal changes in basic physiologic responses of donkeys adapted to the
tropical Savannah. The rectal temperature (RT), respiratory rate (RR) and heart rate (HR) of six male Nubian pack donkeys, and the
dry-bulb temperature (DBT), relative humidity and heat index of the experimental site were concurrently recorded hourly, from
06:00 h to 18:00 h (GMT +1), for three days, spread 1 week apart, during the cold-dry (harmattan), hot-dry and humid (rainy)
seasons, in an open grazing field. Values of the physiologic parameters recorded during the morning (06:00 h–11:00 h) were lower
(P<0.001) than those obtained in the afternoon (12:00 h–15:00 h) and evening (16:00 h–18:00 h) hours in all seasons, but the
robustness of the diurnal rhythm differed (P<0.05) between seasons. Many diurnal hourly DBT mean values recorded during the
harmattan and hot-dry seasons fell outside the established thermoneutral zone for tropically-adapted donkeys, while those obtained
during the rainy season were within the zone, indicating that the dry seasons were more thermally stressful to the donkeys than
the humid season. Overall mean RT dropped (P<0.05) during the harmattan season. The RR rose, while HR dropped (P<0.001)
during the hot-dry season. In conclusion, daytime and season had profound influence on RT, RR and HR of the donkeys, therefore,
diurnal and seasonal variations should be taken into account during clinical evaluation before reaching conclusion on health
status and fitness for work in donkeys.
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Affiliation(s)
- Joseph O Ayo
- Department of Physiology, Faculty of Veterinary Medicine, Ahmadu Bello University, Zaria 800007, Nigeria
| | - Tavershima Dzenda
- Department of Physiology, Faculty of Veterinary Medicine, Ahmadu Bello University, Zaria 800007, Nigeria
| | - Folashade Olaifa
- Department of Physiology, Faculty of Veterinary Medicine, Ahmadu Bello University, Zaria 800007, Nigeria
| | - Stephen A Ake
- Department of Physiology, Faculty of Veterinary Medicine, Ahmadu Bello University, Zaria 800007, Nigeria
| | - Ismaila Sani
- Department of Physiology, Faculty of Veterinary Medicine, Ahmadu Bello University, Zaria 800007, Nigeria
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Lujan HL, DiCarlo SE. Cardiac electrophysiology and the susceptibility to sustained ventricular tachycardia in intact, conscious mice. Am J Physiol Heart Circ Physiol 2014; 306:H1213-21. [PMID: 24561859 DOI: 10.1152/ajpheart.00780.2013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cardiac electrophysiological dysfunction is a major cause of death in humans. Accordingly, electrophysiological testing is routinely performed in intact, conscious, humans to evaluate arrhythmias and disorders of cardiac conduction. However, to date, in vivo electrophysiological studies in mice are limited to anesthetized open-chest or closed-chest preparations. However, cardiac electrophysiology in anesthetized mice or mice with surgical trauma may not adequately represent what occurs in conscious mice. Accordingly, an intact, conscious murine model of cardiac electrophysiology has the potential to be of major importance for advancing the concepts and methods that drive cardiovascular therapies. Therefore, we describe, for the first time, the use of an intact, conscious, murine model of cardiac electrophysiology. The conscious mouse model permits measurements of atrioventricular interval, sinus cycle length, sinus node recovery time (SNRT), SNRT corrected for spontaneous sinus cycle, Wenckebach cycle length, the ventricular effective refractory period (VERP) and the electrical stimulation threshold to induce sustained ventricular tachyarrhythmias in an intact, complex model free of the confounding influences of anesthetics and surgical trauma. This is an important consideration because anesthesia and surgical trauma markedly reduced cardiac output and heart rate as well as altered cardiac electrophysiology parameters. Most importantly, anesthesia and surgical trauma significantly increased the VERP and virtually eliminated the ability to induce sustained ventricular tachyarrhythmias. Accordingly, the methodology allows for the accurate documentation of cardiac electrophysiology in complex, conscious mice and may be adopted for advancing the concepts and ideas that drive cardiovascular research.
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Affiliation(s)
- Heidi L Lujan
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
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Winter P, Kampf T, Helluy X, Gutjahr FT, Meyer CB, Rommel, Bauer WR, Jakob PM, Herold V. Fast retrospectively triggered local pulse-wave velocity measurements in mice with CMR-microscopy using a radial trajectory. J Cardiovasc Magn Reson 2013; 15:88. [PMID: 24083810 PMCID: PMC3850985 DOI: 10.1186/1532-429x-15-88] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 09/03/2013] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND The aortic pulse-wave velocity (PWV) is an important indicator of cardiovascular risk. In recent studies MRI methods have been developed to measure this parameter noninvasively in mice. Present techniques require additional hardware for cardiac and respiratory gating. In this work a robust self-gated measurement of the local PWV in mice without the need of triggering probes is proposed. METHODS The local PWV of 6-months-old wild-type C57BL/6J mice (n=6) was measured in the abdominal aorta with a retrospectively triggered radial Phase Contrast (PC) MR sequence using the flow-area (QA) method. A navigator signal was extracted from the CMR data of highly asymmetric radial projections with short repetition time (TR=3 ms) and post-processed with high-pass and low-pass filters for retrospective cardiac and respiratory gating. The self-gating signal was used for a reconstruction of high-resolution Cine frames of the aortic motion. To assess the local PWV the volume flow Q and the cross-sectional area A of the aorta were determined. The results were compared with the values measured with a triggered Cartesian and an undersampled triggered radial PC-Cine sequence. RESULTS In all examined animals a self-gating signal could be extracted and used for retrospective breath-gating and PC-Cine reconstruction. With the non-triggered measurement PWV values of 2.3±0.2 m/s were determined. These values are in agreement with those measured with the triggered Cartesian (2.4±0.2 m/s) and the triggered radial (2.3±0.2 m/s) measurement. Due to the strong robustness of the radial trajectory against undersampling an acceleration of more than two relative to the prospectively triggered Cartesian sampling could be achieved with the retrospective method. CONCLUSION With the radial flow-encoding sequence the extraction of a self-gating signal is feasible. The retrospective method enables a robust and fast measurement of the local PWV without the need of additional trigger hardware.
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Affiliation(s)
- Patrick Winter
- Julius-Maximilians-Universität Würzburg, Lehrstuhl für Experimentelle Physik 5, Am Hubland, 97074, Würzburg, Germany
| | - Thomas Kampf
- Julius-Maximilians-Universität Würzburg, Lehrstuhl für Experimentelle Physik 5, Am Hubland, 97074, Würzburg, Germany
| | - Xavier Helluy
- Julius-Maximilians-Universität Würzburg, Lehrstuhl für Experimentelle Physik 5, Am Hubland, 97074, Würzburg, Germany
| | - Fabian T Gutjahr
- Julius-Maximilians-Universität Würzburg, Lehrstuhl für Experimentelle Physik 5, Am Hubland, 97074, Würzburg, Germany
| | - Cord B Meyer
- Julius-Maximilians-Universität Würzburg, Lehrstuhl für Experimentelle Physik 5, Am Hubland, 97074, Würzburg, Germany
| | - Rommel
- Julius-Maximilians-Universität Würzburg, Lehrstuhl für Experimentelle Physik 5, Am Hubland, 97074, Würzburg, Germany
| | - Wolfgang R Bauer
- Julius-Maximilians-Universität Würzburg, Medizinische Universitätsklinik, Josef-Schneider Straße 4, 97080, Würzburg, Germany
| | - Peter M Jakob
- Julius-Maximilians-Universität Würzburg, Lehrstuhl für Experimentelle Physik 5, Am Hubland, 97074, Würzburg, Germany
| | - Volker Herold
- Julius-Maximilians-Universität Würzburg, Lehrstuhl für Experimentelle Physik 5, Am Hubland, 97074, Würzburg, Germany
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Nunn N, Feetham CH, Martin J, Barrett-Jolley R, Plagge A. Elevated blood pressure, heart rate and body temperature in mice lacking the XLαs protein of the Gnas locus is due to increased sympathetic tone. Exp Physiol 2013; 98:1432-45. [PMID: 23748904 PMCID: PMC4223506 DOI: 10.1113/expphysiol.2013.073064] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Imbalances of energy homeostasis are often associated with cardiovascular complications. Previous work has shown that Gnasxl-deficient mice have a lean and hypermetabolic phenotype, with increased sympathetic stimulation of adipose tissue. The Gnasxl transcript from the imprinted Gnas locus encodes the trimeric G-protein subunit XLαs, which is expressed in brain regions that regulate energy homeostasis and sympathetic nervous system (SNS) activity. To determine whether Gnasxl knock-out (KO) mice display additional SNS-related phenotypes, we have now investigated the cardiovascular system. The Gnasxl KO mice were ∼20 mmHg hypertensive in comparison to wild-type (WT) littermates (P ≤ 0.05) and hypersensitive to the sympatholytic drug reserpine. Using telemetry, we detected an increased waking heart rate in conscious KOs (630 ± 10 versus 584 ± 12 beats min(-1), KO versus WT, P ≤ 0.05). Body temperature was also elevated (38.1 ± 0.3 versus 36.9 ± 0.4°C, KO versus WT, P ≤ 0.05). To investigate autonomic nervous system influences, we used heart rate variability analyses. We empirically defined frequency power bands using atropine and reserpine and verified high-frequency (HF) power and low-frequency (LF) LF/HF power ratio to be indicators of parasympathetic and sympathetic activity, respectively. The LF/HF power ratio was greater in KOs and more sensitive to reserpine than in WTs, consistent with elevated SNS activity. In contrast, atropine and exendin-4, a centrally acting agonist of the glucagon-like peptide-1 receptor, which influences cardiovascular physiology and metabolism, reduced HF power equally in both genotypes. This was associated with a greater increase in heart rate in KOs. Mild stress had a blunted effect on the LF/HF ratio in KOs consistent with elevated basal sympathetic activity. We conclude that XLαs is required for the inhibition of sympathetic outflow towards cardiovascular and metabolically relevant tissues.
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Affiliation(s)
- Nicolas Nunn
- A. Plagge: Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown Street, Liverpool L69 3BX, UK. . R. Barrett-Jolley: Institute of Ageing and Chronic Disease, 4th floor UCD Building, University of Liverpool, Daulby Str., Liverpool, L69 3GA, UK.
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Lujan HL, DiCarlo SE. Cardiac output, at rest and during exercise, before and during myocardial ischemia, reperfusion, and infarction in conscious mice. Am J Physiol Regul Integr Comp Physiol 2013; 304:R286-95. [PMID: 23302959 DOI: 10.1152/ajpregu.00517.2012] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Multiple systems and regulatory strategies interact to control cardiac homeostasis. In fact, regulated systems, feedback controls, and redundant control mechanisms dominate in whole animals. Accordingly, molecular and cellular tools and techniques must be utilized in complex models with multiple systems and regulatory strategies to fully appreciate the physiological context. Currently, these techniques are mainly performed under conditions remote from the normal in vivo condition; thus, the extrapolation of molecular changes to the in vivo situation and the facilitation of translational aspect of the findings are limited. A major obstacle has been the reliance on preparations that do not mimic the clinical or physiological situation. This is particularly true regarding measurements of cardiac function in mice. To address these concerns, we used a permanently implanted Doppler ultrasonic flow probe on the ascending aorta and coronary artery occluder for repeated measurements of ascending aortic blood flow (cardiac output) in conscious mice, at rest and during exercise, before and during coronary artery occlusion/reperfusion and infarction. The conscious mouse model permits detailed monitoring of within-animal changes in cardiac function during myocardial ischemia, reperfusion, and infarction in an intact, complex model free of the confounding influences of anesthetics, surgical trauma, and restraint stress. Results from this study suggest that previous protocols may have overestimated resting baseline values and underestimated cardiac output reserve. Using these procedures in currently available spontaneous or engineered mouse mutants has the potential to be of major importance for advancing the concepts and methods that drive cardiovascular research.
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Affiliation(s)
- Heidi L Lujan
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA
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Bezerra MA, Lemos A, Lira KDS, Silveira PVC, Coutinho MPG, E Moraes SRA. Does aerobic exercise training promote changes in structural and biomechanical properties of the tendons in experimental animals? A systematic review. Biol Sport 2012; 29:249-54. [PMID: 24868114 PMCID: PMC4033057 DOI: 10.5604/20831862.1019661] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/18/2012] [Indexed: 12/05/2022] Open
Abstract
To develop a systematic review to evaluate, through the best scientific evidence available, the effectiveness of aerobic exercise in improving the biomechanical characteristics of tendons in experimental animals. Two independent assessors conducted a systematic search in the databases Medline/PUBMED and Lilacs/BIREME, using the following descriptors of Mesh in animal models. The ultimate load of traction and the elastic modulus tendon were used as primary outcomes and transverse section area, ultimate stress and tendon strain as secondary outcomes. The assessment of risk of bias in the studies was carried out using the following methodological components: light/dark cycle, temperature, nutrition, housing, research undertaken in conjunction with an ethics committee, randomization, adaptation of the animals to the training and preparation for the mechanical test. Eight studies, comprising 384 animals, were selected; it was not possible to combine them into one meta-analysis due to the heterogeneity of the samples. There was a trend to increasing ultimate load without changes in the other outcomes studied. Only one study met more than 80% of the quality criteria. Physical training performed in a structured way with imposition of overloads seems to be able to promote changes in tendon structure of experimental models by increasing the ultimate load supported. However, the results of the influence of exercise on the elastic modulus parameters, strain, transverse section area and ultimate stress, remain controversial and inconclusive. Such a conclusion must be evaluated with reservation as there was low methodological control in the studies included in this review.
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Affiliation(s)
- M A Bezerra
- Master in Physiotherapy. Federal University of Pernambuco - UFPE, Brazil
| | - A Lemos
- Physiotherapy Department of the Federal University of Pernambuco - UFPE, Brazil
| | - K D S Lira
- Master in Physiotherapy. Federal University of Pernambuco - UFPE, Brazil
| | - P V C Silveira
- Master in Physiotherapy. Federal University of Pernambuco - UFPE, Brazil
| | | | - S R A E Moraes
- Anatomy Department of the Federal University of Pernambuco - UFPE, Brazil
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Human ES-cell-derived cardiomyocytes electrically couple and suppress arrhythmias in injured hearts. Nature 2012; 489:322-5. [PMID: 22864415 PMCID: PMC3443324 DOI: 10.1038/nature11317] [Citation(s) in RCA: 526] [Impact Index Per Article: 43.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Accepted: 06/12/2012] [Indexed: 12/12/2022]
Abstract
Transplantation studies in mice and rats have shown that human embryonic stem cell-derived cardiomyocytes (hESC-CMs) can improve the function of infarcted hearts1–3, but two critical issues related to their electrophysiological behavior in vivo remain unresolved. First, the risk of arrhythmias following hESC-CM transplantation in injured hearts has not been determined. Second, the electromechanical integration of hESC-CMs in injured hearts has not been demonstrated, so it is unclear if these cells improve contractile function directly through addition of new force-generating units. Here we use a guinea pig model to show hESC-CM grafts in injured hearts protect against arrhythmias and can contract synchronously with host muscle. Injured hearts with hESC-CM grafts show improved mechanical function and a significantly reduced incidence of both spontaneous and induced ventricular tachycardia (VT). To assess the activity of hESC-CM grafts in vivo, we transplanted hESC-CMs expressing the genetically-encoded calcium sensor, GCaMP34, 5. By correlating the GCaMP3 fluorescent signal with the host ECG, we found that grafts in uninjured hearts have consistent 1:1 host-graft coupling. Grafts in injured hearts are more heterogeneous and typically include both coupled and uncoupled regions. Thus, human myocardial grafts meet physiological criteria for true heart regeneration, providing support for the continued development of hESC-based cardiac therapies for both mechanical and electrical repair.
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Lo Martire V, Silvani A, Bastianini S, Berteotti C, Zoccoli G. Effects of ambient temperature on sleep and cardiovascular regulation in mice: the role of hypocretin/orexin neurons. PLoS One 2012; 7:e47032. [PMID: 23056568 PMCID: PMC3466227 DOI: 10.1371/journal.pone.0047032] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Accepted: 09/07/2012] [Indexed: 11/18/2022] Open
Abstract
The central neural pathways underlying the physiological coordination between thermoregulation and the controls of the wake-sleep behavior and cardiovascular function remain insufficiently understood. Growing evidence supports the involvement of hypocretin (orexin) peptides in behavioral, cardiovascular, and thermoregulatory functions. We investigated whether the effects of ambient temperature on wake-sleep behavior and cardiovascular control depend on the hypothalamic neurons that release hypocretin peptides. Orexin-ataxin3 transgenic mice with genetic ablation of hypocretin neurons (n = 11) and wild-type controls (n = 12) were instrumented with electrodes for sleep scoring and a telemetric blood pressure transducer. Simultaneous sleep and blood pressure recordings were performed on freely-behaving mice at ambient temperatures ranging between mild cold (20°C) and the thermoneutral zone (30°C). In both mouse groups, the time spent awake and blood pressure were higher at 20°C than at 30°C. The cold-related increase in blood pressure was significantly smaller in rapid-eye-movement sleep (REMS) than either in non-rapid-eye-movement sleep (NREMS) or wakefulness. Blood pressure was higher in wakefulness than either in NREMS or REMS at both ambient temperatures. This effect was significantly blunted in orexin-ataxin3 mice irrespective of ambient temperature and particularly during REMS. These data demonstrate that hypocretin neurons are not a necessary part of the central pathways that coordinate thermoregulation with wake-sleep behavior and cardiovascular control. Data also support the hypothesis that hypocretin neurons modulate changes in blood pressure between wakefulness and the sleep states. These concepts may have clinical implications in patients with narcolepsy with cataplexy, who lack hypocretin neurons.
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Affiliation(s)
- Viviana Lo Martire
- Department of Human and General Physiology, Alma Mater Studiorum – University of Bologna, Bologna, Italy
| | - Alessandro Silvani
- Department of Human and General Physiology, Alma Mater Studiorum – University of Bologna, Bologna, Italy
| | - Stefano Bastianini
- Department of Human and General Physiology, Alma Mater Studiorum – University of Bologna, Bologna, Italy
| | - Chiara Berteotti
- Department of Human and General Physiology, Alma Mater Studiorum – University of Bologna, Bologna, Italy
| | - Giovanna Zoccoli
- Department of Human and General Physiology, Alma Mater Studiorum – University of Bologna, Bologna, Italy
- * E-mail:
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Lujan HL, Janbaih H, Feng HZ, Jin JP, DiCarlo SE. Myocardial ischemia, reperfusion, and infarction in chronically instrumented, intact, conscious, and unrestrained mice. Am J Physiol Regul Integr Comp Physiol 2012; 302:R1384-400. [PMID: 22538514 DOI: 10.1152/ajpregu.00095.2012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the United States alone, the National Heart, Lung, and Blood Institute (NHLBI) has invested several hundred million dollars in pursuit of myocardial infarct-sparing therapies. However, due largely to methodological limitations, this investment has not produced any notable clinical application or cardioprotective therapy. Among the major methodological limitations is the reliance on animal models that do not mimic the clinical situation. In this context, the limited use of conscious animal models is of major concern. In fact, whenever possible, studies of cardiovascular physiology and pathophysiology should be conducted in conscious, complex models to avoid the complications associated with the use of anesthesia and surgical trauma. The mouse has significant advantages over other experimental models for the investigation of infarct-sparing therapies. The mouse is inexpensive, has a high throughput, and presents the ability of one to create genetically modified models. However, successful infarct-sparing therapies in anesthetized mice or isolated mouse hearts may not be successful in more complex models, including conscious mice. Accordingly, a conscious mouse model of myocardial ischemia and reperfusion has the potential to be of major importance for advancing the concepts and methods that drive the development of infarct-sparing therapies. Therefore, we describe, for the first time, the use of an intact, conscious, and unrestrained mouse model of myocardial ischemia-reperfusion and infarction. The conscious mouse model permits occlusion and reperfusion of the left anterior descending coronary artery in an intact, complex model free of the confounding influences of anesthetics and surgical trauma. This methodology may be adopted for advancing the concepts and ideas that drive cardiovascular research.
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Affiliation(s)
- Heidi L Lujan
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan 48201, USA
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Zhang Y, Li L, Hua Y, Nunn JM, Dong F, Yanagisawa M, Ren J. Cardiac-specific knockout of ET(A) receptor mitigates low ambient temperature-induced cardiac hypertrophy and contractile dysfunction. J Mol Cell Biol 2012; 4:97-107. [PMID: 22442497 DOI: 10.1093/jmcb/mjs002] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Cold exposure is associated with oxidative stress and cardiac dysfunction. The endothelin (ET) system, which plays a key role in myocardial homeostasis, may participate in cold exposure-induced cardiovascular dysfunction. This study was designed to examine the role of ET-1 in cold stress-induced cardiac geometric and contractile responses. Wild-type (WT) and ET(A) receptor knockout (ETAKO) mice were assigned to normal or cold exposure (4°C) environment for 2 and 5 weeks prior to evaluation of cardiac geometry, contractile, and intracellular Ca(2+) properties. Levels of the temperature sensor transient receptor potential vanilloid (TRPV1), mitochondrial proteins for biogenesis and oxidative phosphorylation, including UCP2, HSP90, and PGC1α were evaluated. Cold stress triggered cardiac hypertrophy, depressed myocardial contractile capacity, including fractional shortening, peak shortening, and maximal velocity of shortening/relengthening, reduced intracellular Ca(2+) release, prolonged intracellular Ca(2+) decay and relengthening duration, generation of ROS and superoxide, as well as apoptosis, the effects of which were blunted by ETAKO. Western blotting revealed downregulated TRPV1 and PGC1α as well as upregulated UCP2 and activation of GSK3β, GATA4, and CREB in cold-stressed WT mouse hearts, which were obliterated by ETAKO. Levels of HSP90, an essential regulator for thermotolerance, were unchanged. The TRPV1 agonist SA13353 attenuated whereas TRPV1 antagonist capsazepine mimicked cold stress- or ET-1-induced cardiac anomalies. The GSK3β inhibitor SB216763 ablated cold stress-induced cardiac contractile (but not remodeling) changes and ET-1-induced TRPV1 downregulation. These data suggest that ETAKO protects against cold exposure-induced cardiac remodeling and dysfunction mediated through TRPV1 and mitochondrial function.
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Affiliation(s)
- Yingmei Zhang
- Department of Cardiology, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
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Silvani A, Bastianini S, Berteotti C, Lo Martire V, Zoccoli G. Control of cardiovascular variability during undisturbed wake-sleep behavior in hypocretin-deficient mice. Am J Physiol Regul Integr Comp Physiol 2012; 302:R958-64. [PMID: 22357806 DOI: 10.1152/ajpregu.00668.2011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The central neural mechanisms underlying differences in cardiovascular variability between wakefulness, non-rapid-eye-movement sleep (NREMS), and rapid-eye-movement sleep (REMS) remain poorly understood. These mechanisms may involve hypocretin (HCRT)/orexin signaling. HCRT signaling is linked to wake-sleep states, involved in central autonomic control, and impaired in narcoleptic patients. Thus, we investigated whether HCRT signaling plays a role in controlling cardiovascular variability during spontaneous behavior in HCRT-deficient mice. HCRT-ataxin3 transgenic mice lacking HCRT neurons (TG), knockout mice lacking HCRT peptides (KO), and wild-type controls (WT) were instrumented with electrodes for sleep recordings and a telemetric blood pressure transducer. Fluctuations of systolic blood pressure (SBP) and heart period (HP) during undisturbed wake-sleep behavior were analyzed with the sequence technique, cross-correlation functions, and coherent averaging of SBP surges. During NREMS, all mice had lower SBP variability, greater baroreflex contribution to HP control at low frequencies, and greater amplitude of the central autonomic and baroreflex changes in HP associated with SBP surges than during wakefulness. During REMS, all mice had higher SBP variability and depressed central autonomic and baroreflex HP controls relative to NREMS. HP variability during REMS was higher than during NREMS in WT only. TG and KO also had lower amplitude of the cardiac baroreflex response to SBP surges during REMS than WT. These results indicate that chronic lack of HCRT signaling may cause subtle alterations in the control of HP during spontaneous behavior. Conversely, the integrity of HCRT signaling is not necessary for the occurrence of physiological sleep-dependent changes in SBP variability.
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Affiliation(s)
- Alessandro Silvani
- Laboratory of Physiological Regulation in Sleeping Mice, Department of Human and General Physiology, Alma Mater Studiorum-Università di Bologna, Bologna, Italy
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Lujan HL, Janbaih H, Feng HZ, Jin JP, DiCarlo SE. Ventricular function during exercise in mice and rats. Am J Physiol Regul Integr Comp Physiol 2011; 302:R68-74. [PMID: 22012697 DOI: 10.1152/ajpregu.00340.2011] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The mouse has many advantages over other experimental models for the molecular investigation of left ventricular (LV) function. Accordingly, there is a keen interest in, as well as an intense need for, a conscious, chronically instrumented, freely moving mouse model for the determination of cardiac function. To address this need, we used a telemetry device for repeated measurements of LV function in conscious mice at rest and during exercise. For reference, we compared the responses in mice to the responses in identically instrumented conscious rats. The transmitter body of the telemetry device (rat PA-C40; mouse PA-C10; Data Sciences International, St. Paul, MN) was placed in the intraperitoneal space through a ventral abdominal approach (rat) or subcutaneously on the left flank (mouse). The pressure sensor, located within the tip of a catheter, was inserted into the left ventricle through an apical stab wound (18 gauge for rat; 21 gauge for mouse) for continuous, nontethered, recordings of pulsatile LV pressure. A minimum of 1 wk was allowed for recovery and for the animals to regain their presurgical weight. During the recovery period, the animals were handled, weighed, and acclimatized to the laboratory, treadmill, and investigators. Subsequently, LV parameters were recorded at rest and during a graded exercise test. The results document, for the first time, serial assessment of ventricular function during exercise in conscious mice and rats. This methodology may be adopted for advancing the concepts and ideas that drive cardiovascular research.
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Affiliation(s)
- Heidi L Lujan
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan 48201, USA
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Hooijmans CR, Leenaars M, Ritskes-Hoitinga M. A gold standard publication checklist to improve the quality of animal studies, to fully integrate the Three Rs, and to make systematic reviews more feasible. Altern Lab Anim 2010; 38:167-82. [PMID: 20507187 DOI: 10.1177/026119291003800208] [Citation(s) in RCA: 209] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Systematic reviews are generally regarded by professionals in the field of evidence-based medicine as the highest level of medical evidence, and they are already standard practice for clinical studies. However, they are not yet widely used nor undertaken in the field of animal experimentation, even though there is a lot to be gained from the process. Therefore, a gold standard publication checklist (GSPC) for animal studies is presented in this paper. The items on the checklist have been selected on the basis of a literature analysis and the resulting scientific evidence that these factors are decisive in determining the outcome of animal studies. In order to make future systematic reviews and meta-analyses of animal studies possible, to allow others to replicate and build on work previously published, diminish the number of animals needed in animal experimentation (reduction), improve animal welfare (refinement) and, above all, improve the quality of scientific papers on animal experimentation, this publication checklist needs to be used and followed. We have discussed and optimised this GSPC through feedback from interviews with experts in the field of animal experimentation. From these interviews, it became clear that scientists will adopt this GSPC when journals demand it. The GSPC was compared with the current instructions for authors from nine different journals, selected on the basis that they featured a high number of publications on animal studies. In general, the journals' demands for the description of the animal studies are so limited that it is not possible to repeat the studies, let alone carry out a systematic review. By using the GSPC for animal studies, the quality of scientific papers will be improved. The use of the GSPC and the concomitant improvement in the quality of scientific papers will also contribute to decreased variation and increased standardisation and, as a consequence, a reduction in the numbers of animals used and a more reliable outcome of animal studies. It is of major importance that journal editors become convinced of and adopt these recommendations, because only then will scientists follow these guidelines to the full extent.
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Affiliation(s)
- Carlijn R Hooijmans
- Radboud University Nijmegen Medical Centre, Central Animal Laboratory and 3R Research Centre, Geert Grooteplein Noord 29, route 231, 6525 EZ Nijmegen, The Netherlands
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Swoap SJ, Gutilla MJ. Cardiovascular changes during daily torpor in the laboratory mouse. Am J Physiol Regul Integr Comp Physiol 2009; 297:R769-74. [PMID: 19587115 DOI: 10.1152/ajpregu.00131.2009] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The laboratory mouse is a facultative daily heterotherm in that it experiences bouts of torpor under caloric restriction. Mice are the most frequently studied laboratory mammal, and often, genetically modified mice are used to investigate many physiological functions related to weight loss and caloric intake. As such, research documenting the cardiovascular changes during fasting-induced torpor in mice is warranted. In the current study, C57BL/6 mice were implanted either with EKG/temperature telemeters or blood pressure telemeters. Upon fasting and exposure to an ambient temperature (T(a)) of 19 degrees C, mice entered torpor bouts as assessed by core body temperature (T(b)). Core T(b) fell from 36.6 +/- 0.2 degrees C to a minimum of 25.9 +/- 0.9 degrees C during the fast, with a concomitant fall in heart rate from 607 +/- 12 beats per minute (bpm) to a minimum of 158 +/- 20 bpm. Below a core T(b) of 31 degrees C, heart rate fell exponentially with T(b), and the Q(10) was 2.61 +/- 0.18. Further, mice implanted with blood pressure telemeters exhibited similar heart rate and activity profiles as those implanted with EKG/temperature telemeters, and the fall in heart rate and core T(b) during entrance into torpor was paralleled by a fall in blood pressure. The minimum systolic, mean, and diastolic blood pressures of torpid mice were 62.3 +/- 10.2, 51.9 +/- 9.2, 41.0 +/- 7.5 mmHg, respectively. Torpid mice had a significantly lower heart rate (25-35%) than when euthermic at mean arterial pressures from 75 to 100 mmHg, suggesting that total peripheral resistance is elevated during torpor. These data provide new and significant insight into the cardiovascular adjustments that occur in torpid mice.
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Affiliation(s)
- Steven J Swoap
- Dept. of Biology, Williams College, Williamstown, MA 01267, USA.
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Huetteman DA, Bogie H. Direct blood pressure monitoring in laboratory rodents via implantable radio telemetry. Methods Mol Biol 2009; 573:57-73. [PMID: 19763922 DOI: 10.1007/978-1-60761-247-6_4] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The ability to monitor and record precise blood pressure fluctuations in research animals is vital to research for human hypertension. Direct measurement of blood pressure via implantable radio telemetry devices is the preferred method for automatic collection of chronic, continuous blood pressure data. Two surgical techniques are described for instrumenting the two most commonly used laboratory rodent species with radiotelemetry devices. The basic rat procedure involves advancing a blood pressure catheter into the abdominal aorta and placing a radio transmitting device in the peritoneal cavity. The mouse technique involves advancing a thin, flexible catheter from the left carotid artery into the aortic arch and placing the telemetry device under the skin along the animal's flank. Both procedures yield a chronically instrumented model to provide accurate blood pressure data from an unrestrained animal in its home cage.
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Swoap SJ, Li C, Wess J, Parsons AD, Williams TD, Overton JM. Vagal tone dominates autonomic control of mouse heart rate at thermoneutrality. Am J Physiol Heart Circ Physiol 2008; 294:H1581-8. [DOI: 10.1152/ajpheart.01000.2007] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
It is generally accepted that cardiac sympathetic tone dominates the control of heart rate (HR) in mice. However, we have recently challenged this notion given that HR in the mouse is responsive to ambient temperature (Ta) and that the housing Tais typically 21–23°C, well below the thermoneutral zone (∼30°C) of this species. To specifically test the hypothesis that cardiac sympathetic tone is the primary mediator of HR control in the mouse, we first examined the metabolic and cardiovascular responses to rapid changes in Tato demonstrate the sensitivity of the mouse cardiovascular system to Ta. We then determined HR in 1) mice deficient in cardiac sympathetic tone (“β-less” mice), 2) mice deficient in cardiac vagal tone [muscarinic M2receptor ( M2R−/−) mice], and 3) littermate controls. At a Taof 30°C, the HR of β-less mice was identical to that of wild-type mice (351 ± 11 and 363 ± 10 beats/min, respectively). However, the HR of M2R−/−mice was significantly greater (416 ± 7 beats/min), demonstrating that vagal tone predominates over HR control at this Ta. When these mice were calorically restricted to 70% of normal intake, HR fell equally in wild-type, β-less, and M2R−/−mice (ΔHR = 73 ± 9, 76 ± 3, and 73 ± 7 beats/min, respectively), suggesting that the fall in intrinsic HR governs bradycardia of calorically restricted mice. Only when the Tawas relatively cool, at 23°C, did β-less mice exhibit a HR (442 ± 14 beats/min) that was different from that of littermate controls (604 ± 10 beats/min) and M2R−/−mice (602 ± 5 beats/min). These experiments conclusively demonstrate that in the absence of cold stress, regulation of vagal tone and modulation of intrinsic rate are important determinants of HR control in the mouse.
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Ayer A, Antic V, Dulloo AG, Van Vliet BN, Montani JP. Hemodynamic consequences of chronic parasympathetic blockade with a peripheral muscarinic antagonist. Am J Physiol Heart Circ Physiol 2007; 293:H1265-72. [PMID: 17496215 DOI: 10.1152/ajpheart.00326.2007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Whereas the sympathetic nervous system has a well-established role in blood pressure (BP) regulation, it is not clear whether long-term levels of BP are affected by parasympathetic function or dysfunction. We tested the hypothesis that chronic blockade of the parasympathetic nervous system has sustained effects on BP, heart rate (HR), and BP variability (BPV). Sprague-Dawley rats were instrumented for monitoring of BP 22-h per day by telemetry and housed in metabolic cages. After the rats healed from surgery and a baseline control period, scopolamine methyl bromide (SMB), a peripheral muscarinic antagonist, was infused intravenously for 12 days. This was followed by a 10-day recovery period. SMB induced a rapid increase in mean BP from 98 ± 2 mmHg to a peak value of 108 ± 2 mmHg on day 2 of the SMB infusion and then stabilized at a plateau value of +3 ± 1 mmHg above control ( P < 0.05). After cessation of the infusion, the mean BP fell by 6 ± 1 mmHg. There was an immediate elevation in HR that remained significantly above control on the last day of SMB infusion. SMB also induced a decrease in short-term (within 30-min periods) HR variability and an increase in both short-term and long-term (between 30-min periods) BPV. The data suggest that chronic peripheral muscarinic blockade leads to modest, but sustained, increases in BP, HR, and BPV, which are known risk factors for cardiovascular morbidity.
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Affiliation(s)
- Antoine Ayer
- Department of Medicine/Division of Physiology, University of Fribourg, Rue du Musée 5, CH-1700 Fribourg, Switzerland
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Abstract
Torpor, a state characterized by a well-orchestrated reduction of metabolic rate and body temperature (T(b)), is employed for energetic savings by organisms throughout the animal kingdom. The nucleotide AMP has recently been purported to be a primary regulator of torpor in mice, as circulating AMP is elevated in the fasted state, and administration of AMP causes severe hypothermia. However, we have found that the characteristics and parameters of the hypothermia induced by AMP were dissimilar to those of fasting-induced torpor bouts in mice. Although administration of AMP induced hypothermia (minimum T(b) = 25.2 +/- 0.6 degrees C) similar to the depth of fasting-induced torpor (24.9 +/- 1.5 degrees C), ADP and ATP were equally effective in lowering T(b) (minimum T(b): 24.8 +/- 0.9 degrees C and 24.0 +/- 0.5 degrees C, respectively). The maximum rate of T(b) fall into hypothermia was significantly faster with injection of adenine nucleotides (AMP: -0.24 +/- 0.03; ADP: -0.24 +/- 0.02; ATP: -0.25 +/- 0.03 degrees C/min) than during fasting-induced torpor (-0.13 +/- 0.02 degrees C/min). Heart rate decreased from 755 +/- 15 to 268 +/- 17 beats per minute (bpm) within 1 min of AMP administration, unlike that observed during torpor (from 646 +/- 21 to 294 +/- 19 bpm over 35 min). Finally, the hypothermic effect of AMP was blunted with preadministration of an adenosine receptor blocker, suggesting that AMP action on T(b) is mediated via the adenosine receptor. These data suggest that injection of adenine nucleotides into mice induces a reversible hypothermic state that is unrelated to fasting-induced torpor.
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Affiliation(s)
- Steven J Swoap
- Department of Biology, Williams College, Williamstown, MA 01267, USA.
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Abstract
Since its publication in 1996, the Guide for the Care and Use of Laboratory Animals (National Research Council, Washington DC, National Academy Press) has become a primary source of information for institutional animal care and use committees (IACUCs) and research facility managers. In the ensuing years, recommendations relating to laboratory animal care have evolved in response to new scientific information and use of new technology such as ventilated caging. In this article, recent publications are examined to determine the potential impact of new scientific evidence on current practices for the housing and care of laboratory rodents. The discussion points out recent advances in technology and new knowledge of the conditions for the housing of various laboratory rodents, including cage space, single versus group housing, ventilated caging systems, thermoregulation, bedding materials, and enrichment. This new information is provided to aid IACUCs and facility managers in making decisions regarding the housing and care of laboratory rodents.
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Van Vliet BN, McGuire J, Chafe L, Leonard A, Joshi A, Montani JP. Phenotyping the level of blood pressure by telemetry in mice. Clin Exp Pharmacol Physiol 2007; 33:1007-15. [PMID: 17042907 DOI: 10.1111/j.1440-1681.2006.04479.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
1. Using telemetry, arterial blood pressure (BP) can be measured directly over long periods in freely behaving animals without recent anaesthesia or surgery. In the present review, we discuss the strengths and limitations of this method and important considerations in using the method to characterize the BP level in mice. 2. A variety of informative statistics can be used to describe the BP level and we have made available a spreadsheet template for their calculation on a routine basis. The BP level is well summarized using the average value for an entire 24 h period or for the individual light and dark phases of the day. Such long-term averages exhibit less statistical variation than those of short recording periods. In addition, averages of the dark and light phases of the day convey information concerning circadian variations of BP. 3. The frequency distribution of BP samples provides additional information concerning the range of BP values recorded over the course of the day and can be described in terms of percentiles of the distribution that correspond with the minimum and maximum BP values and their span. 4. In mice, BP can be markedly affected by locomotor activity cycles that occur frequently throughout both the light and dark phases of the day. In addition, BP is strongly affected by ambient temperature and food intake, as well as potentially by other determinants of energy balance. Consideration of these factors may help improve accuracy and precision when phenotyping the BP level in mice.
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Affiliation(s)
- Bruce N Van Vliet
- Faculty of Medicine, Memorial University of Newfoundland, St John's, Newfoundland, Canada.
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Perez-Lloret S, Toblli JE, Vigo DE, Cardinali DP, Milei J. Infradian awake and asleep systolic and diastolic blood pressure rhythms in humans. J Hypertens 2006; 24:1273-9. [PMID: 16794475 DOI: 10.1097/01.hjh.0000234106.00745.50] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Blood pressure shows 24-h rhythms with a significant seasonal fluctuation. OBJECTIVES To characterize 2-month to 12-month infradian rhythms in the mean awake and asleep systolic blood pressure (SBP) and diastolic blood pressure (DBP) in humans. METHODS A total of 1689 participants underwent 24-h ambulatory blood pressure monitoring during different periods of the year. The mean daily temperature, humidity, barometric pressure and wind velocity values for the same time span and geographical location were obtained. Fourier analysis was used to fit 12-month, 6-month, 4-month, 3-month and 2-month rhythms to the mean awake and asleep SBP and DBP and to metereological variables. RESULTS The awake mean SBP and DBP values showed significant 12-month and 3-month rhythms (respectively, R2 = 55%, P < 0.001 and R2 = 45% P < 0.001), with a peak in July (winter) and a trough-peak difference of 6.2 +/- 1.6 mmHg (P < 0.001, SBP) and 4.2 +/- 1.5 mmHg (P < 0.001, DBP). In contrast, asleep blood pressure means showed mainly 3-month rhythms (SBP, R2 = 19%, P < 0.02; DBP, R2 = 43% P < 0.02). Mean daily temperature and humidity showed at 12-month, 6-month, 4-month, 3-month and 2-month rhythms, barometric pressure showed 12-month and 6-month rhythms, and wind velocity showed 12-month and 3-month rhythms. Minimal temperature values and maximal humidity values coincided with elevated blood pressure values. CONCLUSION Awake blood pressure means exhibited mainly circannual fluctuations while asleep blood pressure means showed principally 3-month rhythms. Infradian blood pressure variations correlated with some meteorological variables.
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Affiliation(s)
- Santiago Perez-Lloret
- Instituto de Investigaciones Cardiologicas, Prof. Dr. Alberto C. Taquini, Facultad de Medicina, Universidad de Buenos Aires, Argentina
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Evans SA, Parsons AD, Overton JM. Homeostatic responses to caloric restriction: influence of background metabolic rate. J Appl Physiol (1985) 2005; 99:1336-42. [PMID: 15932959 DOI: 10.1152/japplphysiol.01380.2004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The biological responses to caloric restriction (CR) are generally examined in rats with elevated metabolic rates due to being housed at ambient temperatures (Ta) below the zone of thermoneutrality. We determined the physiological and behavioral responses to 2 wk of 30–40% CR in male FBNF1 rats housed in cool (Ta = 12°C) or thermoneutral (TMN; Ta = 30°C) conditions. Rats were instrumented with telemetry devices and housed continuously in home-cage calorimeters for the entire experiment. At baseline, rats housed in cool Ta had reduced rate of weight gain; thus a mild CR (5%) group at thermoneutrality for weight maintenance was also studied. Rats housed in cool Ta exhibited elevated caloric intake (cool = 77 ± 1; TMN = 54 ± 2 kcal), oxygen consumption (V̇o2; cool = 9.9 ± 0.1; TMN = 5.5 ± 0.1 ml/min), mean arterial pressure (cool = 103 ± 1; TMN = 80 ± 2 mmHg), and heart rate (cool = 374 ± 3; TMN = 275 ± 4 beats/min). Cool-CR rats exhibited greater CR-induced weight loss (cool = −62 ± 3; TMN = −42 ± 3 g) and reductions in V̇o2 (cool = −2.6 ± 0.1; TMN = −1.5 ± 0.1 ml/min) but similar CR-induced reductions in heart rate (cool = −59 ± 1; TMN= −51 ± 7 beats/min). CR had no effect on arterial blood pressure or locomotor activity in either group. Unexpectedly, weight maintenance produced significant reductions in V̇o2 and heart rate. At thermoneutrality, a single day of refeeding effectively abolished CR-induced reductions in V̇o2 and heart rate. The results reveal that rats with low or high baseline metabolic rate exhibit comparable compensatory reductions in V̇o2 and heart rate and suggest that Ta can be used to modulate the metabolic background on which the more prolonged effects of CR can be studied.
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Affiliation(s)
- S A Evans
- Department of Biomedical Sciences, Florida State University, Tallahassee, 32306-4340, USA
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