The effects of atrial natriuretic factor and angiotensin II on fetal-placental perfusion pressure in the ex vivo cotyledon model.
OBJECTIVE
Our purpose was to investigate pressure changes induced by angiotensin II on placental vasculature pretreated with atrial natriuretic factor.


METHODS
A dual-perfused cotyledon model was used. Two cotyledons from each placenta were perfused. One cotyledon was infused with atrial natriuretic factor for 30 minutes while the other received an equal volume of saline solution. Three atrial natriuretic factor concentrations were studied: 50 pg/ml, 150 pg/ml, and 15 ng/ml. Both cotyledons received injections of angiotensin II, at the following doses: 1 x 10(-11.5), 1 x 10(-11), 1 x 10(-10.5), and 1 x 10(-10) mol.


RESULTS
Cotyledons subjected to 50 pg/ml and 150 pg/ml concentrations of atrial natriuretic factor did not differ in pressure responses to angiotensin II, compared with the saline-infused cotyledons (p > 0.05). The 15 ng/ml concentration of atrial natriuretic factor, however, decreased the pressor response of angiotensin II (p < 0.034).


CONCLUSIONS
Atrial natriuretic factor decreases vasoconstriction caused by angiotensin II. However, this was seen only at a supraphysiologic concentration. No effect was noted at normal fetal concentrations of atrial natriuretic factor.
D000804:Angiotensin II / Q000494:pharmacology*; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects*; D005260:Female; D005333:Fetus / Q000098:blood supply*; D006801:Humans; D008955:Models, Cardiovascular; D010920:Placenta / Q000098:blood supply*; D011247:Pregnancy; D014661:Vasoconstriction / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D009320:Atrial Natriuretic Factor