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Cardiac and thermal homeostasis in the aging Brown Norway rat.
Citation:
GORDON, C. J. Cardiac and thermal homeostasis in the aging Brown Norway rat. Journal of Gerontology: Biological Sciences. THE GERONTOLOGICAL SOCIETY OF AMERICA, Washington, DC, 63(12):1307-1313, (2008).
Impact/Purpose:
To support criteria for MYP.
Description:
The Brown Norway (BN) rat is a popular strain for aging studies. There is little information on effects of age on baseline cardiac and thermoregulatory parameters in undisturbed BN rats even though cardiac and thermal homeostasis is linked to many pathological deficits in the aged. Male rats obtained at 4, 12, and 24 m of age were implanted with radiotransmitters to monitor the ECG, interbeat interval (IBI), heart rate (HR), core temperature (Tc), and motor activity (MA). Rats were monitored undisturbed for 5 days. The data were averaged into 24 hr bins and analyzed for effects of age on baseline levels and periodicity. There was no significant effect of age on HR and MA; however, there was a notable elevation in HR of the 4 m rats from 6-8 AM compared to the 12 and 24 m groups. Daytime Tc of the 24 m rats was significantly elevated above the 4 and 12 m groups. There was also a trend for reduced 24 h periodicity of Tc with aging. Variability of the IBI was higher in the 24 m rats. In another study, Tc and MA were monitored at 2-3 m intervals in a group of 8 male BN rats from 3 to 24 m. The mean 24 hr Tc decreased slightly from 3 to 8 m and then increased steadily from 8 to 24 m. Daytime but not nighttime Tc was elevated with aging. The elevation in daytime Tc that appears to begin around 8 m of age may be a physiological biomarker of aging in this strain.
