Contractile proteins in human fetoplacental vessels.

OBJECTIVE

Our purpose was to compare the protein isoform composition of the contractile apparatus at different levels of the fetoplacental vessel musculature at term.

STUDY

DESIGN

Umbilical, chorionic, and stem villi vessel protein extracts were run on one- and two-dimensional gel electrophoresis; previously characterized human myometrium proteins were used as the smooth muscle proteins of reference.

RESULTS

Fetoplacental vessel musculature exhibited a high actin/myosin ratio. The presence, in varying quantities, of myosin heavy chain and actin isoforms of smooth muscle type in the different vessels reflected their degree of differentiation. The presence of nonmuscle protein isoforms, particularly in stem villi vessels, indicated a certain degree of immaturity.

CONCLUSIONS

The presence of smooth muscle contractile protein isoforms indicates that fetoplacental vessel musculature is highly differentiated. Regional modulation of fetoplacental blood flow could be, in part, the result of local differences in contractile apparatus protein composition.