Distribution of Cardiac Output during Diurnal Changes of Activity in Rats

摘要

Rat locomotor and feeding behavior varies on a diurnal basis: at night the animals actively forage and eat, whereas during the day they are more inactive and somnolent. At night, cardiac output is higher, presumably for enhanced perfusion of the active muscles to support increased metabolism and for enhanced perfusion of the digestive organs to support increased digestion and nutrient absorption. Conversely, it is hypothesized that during the daytime, blood flow to these two tissues is relatively low. The purpose of this study was to test these hypotheses by measuring cardiac output and the distribution of cardiac output in rats at various times in the diurnal cycle (8:00 A.M., 4:00 P.M., and 8:00 P.M.). (Copyright (c) 1991 the American Physiological Society.)