Effect of Different Doses of Prostaglandin E₁ on Free Fatty Acids of Plasma, Blood Glucose and Heart Rate in the Nonanesthetized Dog Prostaglandin and related factors 53

Prostaglandin E 1 (PGE 1 ) was infused i.v., in doses of 0.2, 0.4, 0.8 and 1.6 μg/kg/min during 30 min in different experiments into nonanesthetized dogs. The smallest dose, 0.2 μg/kg/min, produced a consistent and reproducible increase in venous plasma levels of free fatty acids (FFA). The mean venous plasma level of glycerol showed the same type of response but the rise was not statistically significant. The higher doses of PGE 1 lowered the plasma levels of FFA and glycerol, the highest dose tending to produce the most marked decrease. The average concentration of blood glucose increased at all dose levels but only statistically significant at 0.8 μg/kg/min. The heart rate increased when 0.2–0.8 μg/kg/min of PGE 1 was given. With the highest dose, 1.6 μg/kg/min, the heart rate either tended to increase to a lesser extent or decreased. The increase in plasma levels of FFA and glycerol as well as the increase in heart rate induced by 0.2 μg/kg/min of PGE 1 were abolished after administration of a sympathetic ganglionic blocking agent. The possibility is discussed that PGE 1 not only has a direct inhibitory effect on FFA mobilization from adipose tissue, but may in addition, at low infusion rates, enhance lipid mobilization due to a stimulation of sympathetic nervous activity.