A robust diving response in the laboratory mouse

In this study, telemeters that measure arterial pressure were implanted into male and female C57Bl/6J mice. These mice were trained to voluntarily dive underwater for a distance of 40  cm over a 4–6 s period. Just before the dive, the interbeat interval (IBI) was 87 ± 6 ms (mean ± SD) and diastolic pressure was 99 ± 14 mmHg. Underwater submersion caused (1) a dramatic bradycardia immediately at the onset of each dive, as IBI increased to 458 ± 104 ms, a nd (2) a large drop in diastolic pressure, to 56 ± 16 mmHg despite the elevation in peripheral resistance. Mice experienced a short bout (~ 2 s) of hypertension (diastolic pressure rose to 131 ± 17 mmHg) upon emergence. The bradycardia and hypotension appeared to be vagally mediated, since both these responses were blocked with atropine pre-treatment. These data demonstrate that the mouse exhibits a robust diving response upon voluntary submersion into water.
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - Category: Physiology Source Type: research