The effect of epinephrine on oxygen consumption, overall energy metabolism, and substrate utilization in rats

In this study the influence of epinephrine (E) on oxygen consumption, overall energy metabolism, and substrate utilization in rats has been investigated. Therefore E was infused at rates of 20, 35, and 50 ng/min for 40 min. Infusion of the solvent, saline, served as control experiment. Before, during, and after the infusion, VO2, as parameter for total metabolism, and RQ, as parameter for substrate utilization, were determined using an open circuit. In addition blood samples were taken for determination of blood glucose, plasma free fatty acids (EFA) and plasma insulin concentrations. The results show a rise in VO2 and blood glucose during infusion of E. Plasma FFA concentrations were elevated during infusion of E and of saline. Plasma insulin decreased when E was administered. RQ values were increased when E was infused at rates of 35 and 50 ng/min. The results suggest that E can influence the ratio in which glucose and FFA are utilized. This influence seems to be excerpted indirectly by influencing the availability of the substrates, rather than directly, by influencing utilization.