The lipoprotein composition of amniotic fluid.

Area of Science:

• Biochemistry
• Obstetrics
• Reproductive Biology

Background:

• Amniotic fluid (AF) contains high-density lipoprotein (HDL).
• HDL levels in AF peak around 26 weeks of gestation and decline thereafter.
• AF HDL exhibits distinct electrophoretic properties compared to serum HDL.

Purpose of the Study:

• To characterize the lipoprotein composition of amniotic fluid.
• To investigate the enzymatic activity within amniotic fluid related to lipoprotein transformation.
• To explore the potential role of amniotic fluid components in initiating labor.

Main Methods:

• Crossed immunoelectrophoresis was used to analyze lipoprotein components.
• Antisera against apolipoprotein A-I and HDL were employed for visualization.
• Umbilical cord serum (UCS) was treated with phospholipase A2 and incubated with AF.

Main Results:

• AF HDL separated into two components upon immunoelectrophoresis.
• Maternal and umbilical cord serum contained only the faster-moving lipoprotein component.
• Incubation of UCS with AF or treatment with phospholipase A2 converted the faster component to the slower one.

Conclusions:

• Amniotic fluid likely contains a phospholipase enzyme.
• This enzyme may be responsible for the conversion of serum-like HDL to the slower-moving AF HDL component.
• The presence of this phospholipase in AF suggests a potential role in promoting the onset of labor.