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Research article - Peer-reviewed, 2020

Cardiac adaptation in hibernating, free-ranging Scandinavian Brown Bears (Ursus arctos)

Jorgensen, Peter Godsk; Evans, Alina; Kindberg, Jonas; Olsen, Lisbeth Hoier; Galatius, Soren; Frobert, Ole


During six months of annual hibernation, the brown bear undergoes unique physiological changes to adapt to decreased metabolic rate. We compared cardiac structural and functional measures of hibernating and active bears using comprehensive echocardiography. We performed echocardiography on 13 subadult free-ranging, anaesthetised Scandinavian brown bears (Ursus arctos) during late hibernation and in early summer. Mean heart rate was 26 beats per minute (standard deviation (SD): 8) during hibernation vs 71 (SD: 14) during active state. All left ventricular (LV) systolic and diastolic measures were decreased during hibernation: mean ejection fraction: 44.2% (SD: 6.0) active state vs 34.0 (SD: 8.1) hibernation, P = 0.001; global longitudinal strain: -11.2% (SD: 2.0) vs -8.8 (SD: 3.3), P = 0.03; global longitudinal strain rate: -0.82 (SD: 0.15) vs -0.41 (SD: 0.18), P < 0.001; septal e': 9.8 cm/s (SD: 1.8) vs 5.2 (SD: 2.7), P < 0.001. In general, measures of total myocardial motion (ejection fraction and global longitudinal strain) were decreased to a lesser extent than measures of myocardial velocities. In the hibernating brown bear, cardiac adaptation included decreased functional measures, primarily measures of myocardial velocities, but was not associated with cardiac atrophy. Understanding the mechanisms of these adaptations could provide pathophysiological insight of human pathological conditions such as heart failure.

Published in

Scientific Reports
2020, volume: 10, number: 1, article number: 247

Authors' information

Jorgensen, Peter Godsk
Univ Copenhagen
Evans, Alina
Inland Norway Univ Appl Sci
Swedish University of Agricultural Sciences, Department of Wildlife, Fish and Environmental Studies
Norwegian Institute for Nature Research (NINA)
Olsen, Lisbeth Hoier
Univ Copenhagen
Galatius, Soren
Univ Copenhagen
Frobert, Ole
Orebro Univ Hosp

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