Low cardiac output as physiological phenomenon in hibernating, free-ranging Scandinavian brown bears (Ursus arctos) – an observational study

Cardiovascular Ultrasound

Research

Peter Godsk Jørgensen¹  Søren Galatius¹  Jan S Jensen¹  Ole Frøbert²  Jon E Swenson³  Jon Arnemo⁴ 

[1] Department of Cardiology, University of Copenhagen, Gentofte Hospital, Copenhagen, Denmark;Department of Cardiology, Örebro University Hospital, Örebro, Sweden;Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, NO-1528, Ås, Norway;Norwegian Institute for Nature Research, NO-7485, Trondheim, Norway;Department of Forestry and Wildlife Management, Faculty of Applied Ecology and Agricultural Sciences, Hedmark College, Campus Evenstad, NO-2418, Elverum, Norway;Department of Wildlife, Fish and Environmental Studies, Faculty of Forest Sciences, Swedish University of Agricultural Sciences, SE-901 83, Umeå, Sweden;

关键词: Animal model cardiovascular disease;    Acute cardiac care;    Thrombosis;    Echocardiography;   

DOI  :  10.1186/1476-7120-12-36

 received in 2014-08-15, accepted in 2014-09-09,  发布年份 2014

来源: Springer

【 摘 要 】

BackgroundDespite 5-7 months of physical inactivity during hibernation, brown bears (Ursus arctos) are able to cope with physiological conditions that would be detrimental to humans. During hibernation, the tissue metabolic demands fall to 25% of the active state. Our objective was to assess cardiac function associated with metabolic depression in the hibernating vs. active states in free-ranging Scandinavian brown bears.MethodsWe performed echocardiography on seven free-ranging brown bears in Dalarna, Sweden, anesthetized with medetomidine-zolazepam-tiletamine-ketamine during winter hibernation in February 2013 and with medetomidine-zolazepam-tiletamine during active state in June 2013. We measured cardiac output noninvasively using estimates of hemodynamics obtained by pulsed wave Doppler echocardiography and 2D imaging. Comparisons were made using paired T-tests.ResultsDuring hibernation, all hemodynamic indices were significantly decreased (hibernating vs. active state): mean heart rate was 26.0 (standard deviation (SD): 5.6) beats per min vs. 75.0 (SD: 17.1) per min (P = 0.002), mean stroke volume 32.3 (SD: 5.2) ml vs. 47.1 (SD: 7.9) ml (P = 0.008), mean cardiac output 0.86 (SD: 0.31) l/min vs. 3.54 (SD: 1.04) l/min (P = 0.003), and mean cardiac index 0.63 (SD: 0.21) l/min/kg vs. 2.45 (SD: 0.52) l/min/ m2 (P < 0.001). Spontaneous echo contrast was present in all cardiac chambers in all seven bears during hibernation, despite the absence of atrial arrhythmias and valvular disease.ConclusionFree-ranging brown bears demonstrate hemodynamics comparable to humans during active state, whereas during hibernation, we documented extremely low-flow hemodynamics. Understanding these physiological changes in bears may help to gain insight into the mechanisms of cardiogenic shock and heart failure in humans.

【 授权许可】

CC BY   
© Jørgensen et al.; licensee BioMed Central Ltd. 2014