Adrenal glands of foetal sheep of 40 days gestation to term were incubated with and without ACTH or an increased [K+]. With ACTH, the 40 day foetal adrenal was capable of producing more cortisol and aldosterone per g body weight than was the term adrenal. ACTH was a potent stimulus to aldosterone and cortisol production in foetuses aged 60\p=n-\90days, and this effect declined significantly in the 91\p=n-\120day period. An increased [K+] was stimulatory to aldosterone production only after 120 days gestation. Peripheral blood levels of aldosterone, corticosterone, cortisol, 11-deoxycortisol and 11-deoxycorticosterone were measured in foetuses 60 days to term and the levels of aldosterone and cortisol were significantly lower in 90\p=n-\120day foetuses than in the younger or older ones. Direct adrenal vein cannulation proved all five steroids to be secretory products of the foetal adrenal.The ovine foetal cortex has been shown to play a significant role in the onset of parturition in this species (Liggins 1968) and for this reason its ability to
Summary. Whole blood concentrations of aldosterone and corticosterone were measured in female rats on a moderate sodium diet (1-2 mmol/day) during diestrus, proestrus, oestrus and on days 4, 12, 18 of pregnancy. At diestrus, the aldosterone (5-6 ± 4-9 ng/100 ml., n = 4) and corticosterone (10-4 it 10-7 ng/lOO ml, n = 4) concentrations were significantly lower (P < 0-01) than at oestrus when aldosterone and corticosterone concentrations were respectively 15-2 ± 7-8 ng/100 ml (n = 6) and 27-2 ± 12 2 ng/100 ml (n = 6). The blood aldosterone concentration of day-12 pregnant rats, 33-9 ± 7-8 ng/ 100 ml (n = 8), was significantly higher than the values at oestrus and remained elevated at day 18. (Parturition occurs at day 21-22.) Corticosterone values were not elevated during pregnancy, compared to values at oestrus. Sodium loading (7-8 m mol/day) did not suppress blood aldosterone concentrations in non-pregnant rats, but did significantly (P < 0 05) suppress values in the 18-20 day pregnant rat. Plasma renin concentration (PRC), plasma renin substrate (PRS) and derived plasma renin activity (PRA) did not vary significantly during the oestrous cycle, being respectively (18-3 ± 10 7) x 10-Ĝ oldblatt Units/ml, 0-416 ± 0-199 ng/ml, and 5-0 ± 2-6 ng/ml/h in 21 samples. PRC increased significantly by day 11 of gestation, while PRS decreased significantly at day 11 (P < 0-05) and even further by days 18-20 (P < 0-001).The derived PRA was elevated only in 11-14 day pregnant rats (P < 0-05). It is concluded that factors other than renin are responsible for the increase in aldosterone in pregnancy. INTRODUGTIONDuring the course of pregnancy in the rat (21-22 days) there is a great demand for sodium conservation, as a weight gain of approx. 45% of the original maternal body weight is made, 60% of this occurring during the last third of
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.