RESUMEN
The influence of plasma free fatty acid (FFA) concentration on the secretion of human placental lactogen (hPL) was investigated in 16 normal young women during the last month of gestation, in order to determine whether hPL secretion is influenced in the same way as human growth hormone (hGH) during plasma FFA elevation. Maternal blood glucose (BG), plasma triglycerides (TG), FFA, immunoreactive insulin (IRI) and hPL levels were measured during and after a lipid emulsion infusion for 75 min (10 cases). The intravenous injection of 5,000 U of heparin at the 15th min of the lipid infusion was followed by a decrease in plasma triglyceride levels and by an accompanying rise in plasma FFA (rom 468 plus or minus 52 to 2,478 plus or minus 310 mueq/liter). In control experiments lipid infusion alone (3 cases) resulted in a moderate increase in FFA (718 plus or minus 157 to 1,046 plus or minus 255 mueq/liter), and separate iv heparin administration (3 cases) elevated the FFA levels from 728 plus or minus 50 to 1,649 plus or minus 153 mueq/liter). No significant change in either IRI or hPL levels was discernible in any of the tests performed. A tendency of blood glucose to increase was observed after heparin administration. It was concluded that a marked and sustained plasma FFA elevation, achieved through intravenous lipid and heparin infusion cannot alter hPL circulating levels in term human pregnancy.