Effects of norethisterone on pressor response to angiotensin II in men.
OBJECTIVE
We examined the effects of norethisterone and/or mestranol on the pressor response to angiotensin II in 20 healthy men.


METHODS
Four study protocols were used: I) mestranol 0.08 mg/day for 6 days followed by mestranol plus norethisterone 20 mg/day for 6 days, II) mestranol 0.16 mg/day for 6 days followed by norethisterone alone 10 mg/day for 6 days, III) mestranol 0.24 mg/day followed by norethisterone 20 mg/day for 6 days, and IV) norethisterone 20 mg/day for 6 days. The angiotensin II dose to elicit a 20-mmHg rise in diastolic blood pressure was considered the effective pressor dose. This was determined before each protocol, at the end of the mestranol-alone portion, and at the end of the norethisterone portion. Subjects in study III also underwent measurement of plasma prostanoid levels, plasma renin activity and concentration, and estradiol and progesterone just before each angiotensin II infusion. Subjects in studies I and III underwent measurement of mean platelet volume, complete blood counts, liver function tests, and coagulation factors before each angiotensin II infusion.


RESULTS
Whereas mestranol had no apparent effect on angiotensin II pressor response, norethisterone at a dose of 20 mg/day (with or without concurrent mestranol administration) caused a significant decrease in pressor responsiveness to angiotensin II. No changes in plasma prostanoids or renin could be found that would account for the change in pressor response.


CONCLUSIONS
These findings indicate that the refractoriness to angiotensin II induced by norethisterone was related to its progestogenic properties.
Mabe
K
K
Department of Obstetrics and Gynecology, Kumamoto University Medical School, Japan.
Ito
M
M
Okamura
H
H
D015121:6-Ketoprostaglandin F1 alpha / Q000097:blood; D000328:Adult; D000804:Angiotensin II / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects*; D004958:Estradiol / Q000097:blood; D006400:Hematocrit; D006801:Humans; D008297:Male; D008656:Mestranol / Q000494:pharmacology; D009640:Norethindrone / Q000494:pharmacology*; D011374:Progesterone / Q000097:blood; D012083:Renin / Q000097:blood; D013929:Thromboxane B2 / Q000097:blood
D000804:Angiotensin II; D011374:Progesterone; D004958:Estradiol; D013929:Thromboxane B2; D015121:6-Ketoprostaglandin F1 alpha; D008656:Mestranol; D012083:Renin; D009640:Norethindrone