Studies on placental inhibition of platelet aggregation: a comparison of human syncytiotrophoblast brush border and basal plasma membranes.
We compared the platelet aggregation inhibiting activity of human placental syncytiotrophoblast brush border membrane vesicles (BBMV) and basal plasma membrane vesicles (BpMV), and obtained the following results. Strong platelet aggregation inhibiting activity is found in placental BBMV. BBMV inhibited platelet aggregation induced by ADP (adenosine diphosphate) and arachidonic acid in a way which depended on the protein concentration of BBMV added. In contrast, BpMV showed no detectable platelet aggregation inhibiting activity. Quite high ADP degrading activity (ADPase activity) was present in the placental BBMV. ADP was quickly degraded by BBMV. In contrast, BpMV did not degrade ADP so quickly. Platelet TXB2 production was almost completely abolished at the protein concentration of 40 micrograms/ml of BBMV. In contrast, BpMV did not significantly inhibit platelet TXA2 (TXB2) production. These results show that syncytiotrophoblast brush border and basal plasma membranes of the human placenta have markedly different properties with respect to platelet aggregation inhibiting activity.
Iioka
H
H
Department of Obstetrics and Gynecology, Nara Medical University, Japan.
Akada
S
S
Shimamoto
T
T
Yamada
Y
Y
Sakamoto
Y
Y
Yoshida
T
T
Ichijo
M
M
D000244:Adenosine Diphosphate / Q000494:pharmacology; D001081:Apyrase / Q000378:metabolism; D016718:Arachidonic Acid / Q000494:pharmacology; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism; D002462:Cell Membrane / Q000502:physiology; D005260:Female; D006801:Humans; D008871:Microvilli / Q000502:physiology; D010920:Placenta / Q000502:physiology*; D010974:Platelet Aggregation; D011247:Pregnancy; D011506:Proteins / Q000378:metabolism; D013928:Thromboxane A2 / Q000378:metabolism; D013929:Thromboxane B2 / Q000037:antagonists & inhibitors; D014327:Trophoblasts / Q000502:physiology*
D011506:Proteins; D016718:Arachidonic Acid; D013929:Thromboxane B2; D013928:Thromboxane A2; D000244:Adenosine Diphosphate; D001081:Apyrase