The effect of fetal pulmonary surfactant production on the apparent microviscosity of amniotic fluid measured by fluorescence polarization

Abstract

The fluorescence properties of 1,6 diphenyl 1,3,5-hexatriene (DPH) in human amniotic fluid from the 10–20th week and from the 36–40th week of gestation are investigated. The probe environment of two stages of fetal development are studied by measuring the effect of temperature on the fluorescence polarization of DPH. The temperature profiles of fluorescence polarization of DPH in amniotic fluid and in liposomes prepared from chloroform/methanol extracts of the fluid are compared to the temperature profiles of liposomes prepares from phospholipids of known composition. The DPH binding structures of human amniotic fluid are further characterized by fractionation of lipid bodies by centrifugation on a Ficoll density gradient. The major part of fluorescence in third trimester amniotic fluid is emitted by DPH bound to pulmonary lamellar lipid bodies. The DPH environment in early gestational amniotic fluid is a distinctly different structure, which is more rigid than both sphingomyelin and dipalmityl lecithin at temperatures above 40°C, and which is not chloroform/methanol extractable.

Key Words:

• 1,6 diphenyl 1,3,5-hexatriene
• lamellar lipid bodies
• lung maturation