RESUMO
The plasma levels of enzymatically active renin (active renin) and inactive renin (prorenin) were measured in a woman with primary ovarian failure, in whom pregnancy was established by the induction of an artificial cycle and in vitro fertilization of a donated oocyte fertilized with the sperm of her husband. The results were compared with those in nine normal pregnant women. Prepregnancy plasma active renin and prorenin levels were normal in the patient. Active renin rose 2-fold during pregnancy in both the patient and the normal pregnant women. In the first 8 weeks of pregnancy prorenin rose by 156 microU/mL in the patient, whereas it rose by 869 +/- 169 microU/mL (mean +/- SD) in the normal pregnant women. Thus, the rise in prorenin in our patient was much less than normal. Prorenin remained abnormally low throughout the pregnancy, which lasted 40 weeks. Therefore, the high prorenin levels that occur normally during pregnancy may depend on normal ovarian function. Amniotic fluid prorenin in the patient was similar to that in normal pregnant women and was 75 times higher than that in plasma. This finding suggests that prorenin production by the chorionic cells was normal in the patient and that chorionic prorenin does not contribute in any major degree to the level of prorenin in maternal plasma. Because of these findings and in light of recent evidence that the ovary secretes prorenin and produces high plasma prorenin levels in women with hyperstimulated cycles, we conclude that the ovary is the main source of the elevated plasma prorenin levels in pregnant women.
