Relationship Between Ambient Temperature and the Spontaneous Running Activity of Normal and Hypertensive Rats

¹ From the Department of Physiology, Harvard Medical School, Boston, Massachusetts

When daily illumination is held constant, lowering ambient temperature increases spontaneous running activity of both normal and hypertensive rats in a sigmoid fashion. The spontaneous activities of normal and hypertensive rats were similar in the range of ambient temperatures from 25–30°C. At all temperatures lower than 25°C, viz. 20, 15 and 10°C, the activity of normal rats was significantly higher than that of hypertensive rats. Hence, hypertension appeared to limit the increased running activity normally observed in cold air.