Renin and Prorenin in Reproductive Tissues During Gestation in Pigs and Cattle

Abstract

1. High concentrations of prorenin and active renin were previously found in ovarian follicular fluid from cattle but not from pigs. In the present study female reproductive tissues and fluids from cattle and pigs during gestation were investigated to clarify a possible species difference in active renin and prorenin concentrations. 2. Very high concentrations of active renin but no prorenin were found in corpus luteum from both species. 3. Relatively low concentrations of active renin, in the same order as in maternal blood plasma, were found in myometrium, endometrium, placenta and fetal membranes from both species. Prorenin was undetectable in these tissues except for bovine myometrium and porcine endometrium in some animals. 4. The concentrations of active renin and prorenin in amnionic fluid from both species were below the maternal plasma values. In allantoic fluid the concentrations were higher than in amnionic fluid. 5. The plasma concentrations of active renin and prorenin did not change during gestation in pigs. This finding is in contrast to the observations in humans and does not support a systemic effect of prorenin during gestation. 6. The presence of renin in the reproductive tissues, especially the very high concentrations in the corpus luteum, indicates a local function of the renin-angiotensin system during gestation.

Autoradiographic Localization and Characterization of Angiotensin II Receptors in the Bovine Placenta and Fetal Membranes1

“…This is in accordance with previous findings [20]. In the present study, enzymatically inactive renin (prorenin) was not determined.…”

“…In the present study, enzymatically inactive renin (prorenin) was not determined. In an earlier study, however, no prorenin was detected in the bovine placenta [20]. This is in contrast to the human placenta, which-with the kidney-is a main source of the increased prorenin in the plasma during pregnancy [33,34].…”

“…This method was previously described in more detail for the measurement of renin in bovine plasma, ovarian follicular fluid, and tissues [19][20][21]. The assay was standardized against a hog renin standard (Medical Research Council, Holly Hill, London, UK), and the renin concentrations are given as Goldblatt units (GU) per liter.…”

First Report Of Active Renin In Rat Amniotic Fluid

“…Furthermore, there are increased, but equivalent, concentrations of both active renin and prorenin in the human decidua, endometrium and myometrium, in which the latter two tissues collectively make up the lining of the uterus. 17,20 Alterations in the activity of the intra-uterine RAS could alter fetal cardiovascular development in such a way that it sets in train a longterm hypertrophic and hypertensive process in offspring. Previous studies have also found that the concentrations of prorenin and active renin in the human amniotic fluid are approximately 40-and 15fold higher, respectively, than in maternal plasma 19 and significantly higher than both active and inactive renin content in fetal plasma.…”

“…13 In contrast with these findings in human pregnancy, there is low or non-detectable prorenin and active renin in the amniotic fluid of animals with low expression of RAS in their uteroplacental unit, such as the rat, pig and cat. 17,20 Alterations in the activity of the intra-uterine RAS could alter fetal cardiovascular development in such a way that it sets in train a longterm hypertrophic and hypertensive process in offspring. Thus, we hypothesized that overexpression of the in utero RAS results in fetal growth restriction and, thus, could be a causative factor in the prenatal programming of later hypertension.…”