The blood pressure response to infusions of angiotensin II during normal pregnancy: relation to plasma angiotensin II concentration, serum progesterone level, and mean platelet volume.
OBJECTIVE
This study is a survey of the determinants of refractoriness to the pressor effects of angiotensin II during normal pregnancy.


METHODS
In 25 normal pregnant women, the effective angiotensin II pressor dose was determined 88 times from the twenty-fifth to the thirty-second week of gestation. Immediately before the angiotensin II infusion, blood samples were collected and measured for plasma angiotensin II concentration, serum progesterone level, platelet count, and mean platelet volume.


RESULTS
The effective pressor dose had a significantly positive correlation with plasma angiotensin II concentration and serum progesterone level and a negative correlation with mean platelet volume.


CONCLUSIONS
The pregnancy-associated refractoriness to angiotensin II is physiologically determined, at least in part, by the elevated circulating levels of endogenously produced angiotensin II and by the progesterone produced by the placenta, whereas platelet activation attenuates the relative refractoriness during normal pregnancy.
Ito
M
M
Department of Obstetrics and Gynecology, Kumamoto University Medical School, Japan.
Nakamura
T
T
Yoshimura
T
T
Koyama
H
H
Okamura
H
H
D000804:Angiotensin II / Q000097:blood / Q000494:pharmacology*; D001792:Blood Platelets / Q000166:cytology* / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D009994:Osmolar Concentration; D010976:Platelet Count / Q000187:drug effects; D011247:Pregnancy; D011374:Progesterone / Q000097:blood*; D012016:Reference Values
D000804:Angiotensin II; D011374:Progesterone