Concentrations of glycerol and non-esterified fatty acids in plasma during fat mobilization.

The presence of fat-mobilizing activity in the pituitary gland was first demonstrated by Best & Campbell (1936). More recently a series of studies have been carried out on a lipid-mobilizing factor which has been extensively purified from the anterior pituitary gland (Rudman & Seidman, 1958; Rudman, Seidman & Reid, 1960; Di Girolamo, Rudman, Reid & Seidman, 1961; Rudman, Seidman, Brown & Hirsch, 1962) and its action appears to be adequately explained by the following sequence of events after its administration. 1. Increased hydrolysis of triglycerides in adipose tissue. 2. Release of the free fatty acids produced by this hydrolysis into the bloodstream, where they are bound to the albumin. 3. Transport of the albumin-bound free fatty acids to other tissues, including the liver. 4. Conversion of a proportion of free fatty acids carried to the liver into triglycerides which are returned to the plasma in the low-density lipoproteins, with a resultant rise in the concentration of blood triglyceride. Little is yet known of the fate of the glycerol, which is also formed during the hydrolysis of the adipose-tissue triglycerides. In this paper the effect of a purified lipid-mobilizing factor from the anterior pituitary gland on the concentrations of glycerol and free fatty acids in the plasma is investigated.