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 st em villi vessel protein extracts were run on one- and two-dimensional gel electrophoresis; previously characterized human myometrium protein s were used as the smooth muscle proteins of reference. RESULTS: Fetop lacental vessel musculature exhibited a high actin/myosin ratio. The p resence, in varying quantities, of myosin heavy chain and actin isofor ms of smooth muscle type in the different vessels reflected their degr ee of differentiation. The presence of nonmuscle protein isoforms, par ticularly in stem villi vessels, indicated a certain degree of immatur ity. CONCLUSIONS: The presence of smooth muscle contractile protein is oforms indicates that fetoplacental vessel musculature is highly diffe rentiated. Regional modulation of fetoplacental blood flow could be, i n part, the result of local differences in contractile apparatus prote in composition.