Basic Science and Experimental StudiesCircadian Body Temperature Variability is an Indicator of Poor Prognosis in Cardiomyopathic Hamsters
Section snippets
Animals
This study was approved and conducted according to the guidelines of the University of Texas Health Science Center Animal Welfare Committee. Each hamster was housed separately in an airtight plastic cage. The cages were placed in a modified cage rack (Alternative Designs, Inc, Siloam Springs, AR) that was equipped with a blower to provide air circulation and a hydration system to provide fresh water. We continuously monitored the temperatures in empty cages attached to the rack to ensure that
Results
Data from 44 hamsters were included in our final analysis. The average survival time of the hamsters was 365 ± 41 days (from birth to death). Plots of the Kaplan-Meier estimates of conditional probability of survival to a given age in the experimental and control groups of hamsters are shown in Fig. 1. The hamsters weighed an average of 108.9 ± 9.5 g at baseline (after transmitter implantation) and 132.8 ± 21.3 g at death.
Discussion
In addition to the consistent temperature decline seen 8 ± 4 days before death in the majority of cardiomyopathic hamsters, we observed that the amplitude of the body temperature circadian rhythm was significantly lower 8 weeks before death than at baseline.
Heart failure is a complex clinical syndrome characterized by physiologic compensatory efforts that become pathologic, centering on sympathetic neurohormonal activation. Sympathetic reflex dominance is associated with a loss of reflex
Conclusions
We observed that declining body temperature variability predicted decompensation or death in cardiomyopathic hamsters. By using frequency domain analysis, we saw a loss in temperature variability before changes in body weight or physical activity occurred, suggesting that this analysis may be a useful means of identifying opportunities for therapeutic intervention. More studies are necessary to determine whether the interventions known to influence outcomes in heart failure can affect animals
Acknowledgments
We would like to thank Hilary Marks, PhD, for editorial assistance in the preparation of this manuscript.
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The authors have no conflicts of interest.
The Texas Training and Technology for Trauma and Terrorism (T5) Program, supported by the US Army's Telemedicine & Advanced Technology Research Center (TATRC), sponsored portions of this research.