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Wiegel RE, von Versen-Höynck F, Steegers-Theunissen RPM, Steegers EAP, Danser AHJ. Prorenin periconceptionally and in pregnancy: Does it have a physiological role? Mol Cell Endocrinol 2021; 529:111281. [PMID: 33878417 DOI: 10.1016/j.mce.2021.111281] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 11/24/2020] [Accepted: 12/06/2020] [Indexed: 12/30/2022]
Abstract
Pregnancy demands major cardiovascular, renal and endocrine changes to provide an adequate blood supply for the growing fetus. The renin-angiotensin-aldosterone system plays a key role in this adaptation process. One of its components, prorenin, is released in significant amounts from the ovary and uteroplacental unit. This review describes the sources of prorenin in the periconception period and in pregnancy, including its modulation by in-vitro fertilization protocols, and discusses its potential effects, among others focusing on preeclampsia. It ends with discussing the long-term consequences, even in later life, of inappropriate renin-angiotensin-aldosterone system activity in pregnancy and offers directions for future research. Ultimately, a full understanding of the role of prorenin periconceptionally and during pregnancy will help to develop tools to diagnose and/or prevent reproductive complications.
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Affiliation(s)
- Rosalieke E Wiegel
- Departments of Obstetrics and Gynecology, Erasmus MC, Rotterdam, the Netherlands
| | | | | | - Eric A P Steegers
- Departments of Obstetrics and Gynecology, Erasmus MC, Rotterdam, the Netherlands
| | - A H Jan Danser
- Department of Internal Medicine, Erasmus MC, Rotterdam, the Netherlands.
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2
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Wiegel RE, von Versen-Höynck F, Steegers-Theunissen RPM, Steegers EAP, Danser AHJ. Prorenin periconceptionally and in pregnancy: Does it have a physiological role? Mol Cell Endocrinol 2021; 522:111118. [PMID: 33340569 DOI: 10.1016/j.mce.2020.111118] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 11/24/2020] [Accepted: 12/06/2020] [Indexed: 01/19/2023]
Abstract
Pregnancy demands major cardiovascular, renal and endocrine changes to provide an adequate blood supply for the growing fetus. The renin-angiotensin-aldosterone system plays a key role in this adaptation process. One of its components, prorenin, is released in significant amounts from the ovary and uteroplacental unit. This review describes the sources of prorenin in the periconception period and in pregnancy, including its modulation by in-vitro fertilization protocols, and discusses its potential effects, among others focusing on preeclampsia. It ends with discussing the long-term consequences, even in later life, of inappropriate renin-angiotensin-aldosterone system activity in pregnancy and offers directions for future research. Ultimately, a full understanding of the role of prorenin periconceptionally and during pregnancy will help to develop tools to diagnose and/or prevent reproductive complications.
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Affiliation(s)
- Rosalieke E Wiegel
- Department of Obstetrics and Gynecology, Erasmus MC, Rotterdam, the Netherlands
| | | | | | - Eric A P Steegers
- Department of Obstetrics and Gynecology, Erasmus MC, Rotterdam, the Netherlands
| | - A H Jan Danser
- Department of Internal Medicine, Erasmus MC, Rotterdam, the Netherlands.
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3
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Boeldt DS, Bird IM. Vascular adaptation in pregnancy and endothelial dysfunction in preeclampsia. J Endocrinol 2017; 232:R27-R44. [PMID: 27729465 PMCID: PMC5115955 DOI: 10.1530/joe-16-0340] [Citation(s) in RCA: 187] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 10/11/2016] [Indexed: 12/27/2022]
Abstract
Maternal vascular adaptation to pregnancy is critically important to expand the capacity for blood flow through the uteroplacental unit to meet the needs of the developing fetus. Failure of the maternal vasculature to properly adapt can result in hypertensive disorders of pregnancy such as preeclampsia (PE). Herein, we review the endocrinology of maternal adaptation to pregnancy and contrast this with that of PE. Our focus is specifically on those hormones that directly influence endothelial cell function and dysfunction, as endothelial cell dysfunction is a hallmark of PE. A variety of growth factors and cytokines are present in normal vascular adaptation to pregnancy. However, they have also been shown to be circulating at abnormal levels in PE pregnancies. Many of these factors promote endothelial dysfunction when present at abnormal levels by acutely inhibiting key Ca2+ signaling events and chronically promoting the breakdown of endothelial cell-cell contacts. Increasingly, our understanding of how the contributions of the placenta, immune cells, and the endothelium itself promote the endocrine milieu of PE is becoming clearer. We then describe in detail how the complex endocrine environment of PE affects endothelial cell function, why this has contributed to the difficulty in fully understanding and treating this disorder, and how a focus on signaling convergence points of many hormones may be a more successful treatment strategy.
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Affiliation(s)
- D S Boeldt
- Department of Ob/GynPerinatal Research Laboratories, University Wisconsin - Madison, Madison, Wisconsin, USA
| | - I M Bird
- Department of Ob/GynPerinatal Research Laboratories, University Wisconsin - Madison, Madison, Wisconsin, USA
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Thomas P, Pang Y. Protective actions of progesterone in the cardiovascular system: potential role of membrane progesterone receptors (mPRs) in mediating rapid effects. Steroids 2013; 78:583-8. [PMID: 23357432 DOI: 10.1016/j.steroids.2013.01.003] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Revised: 01/04/2013] [Accepted: 01/14/2013] [Indexed: 02/06/2023]
Abstract
The protective functions of progesterone in the cardiovascular system have received little attention even though evidence has accumulated that progesterone lowers blood pressure, inhibits coronary hyperactivity and has powerful vasodilatory and natriuretic effects. One possible reason why potential beneficial actions of progesterone on cardiovascular functions have not been extensively studied is that divergent effects to those of progesterone have been observed in many clinical trials with synthetic progestins such as medroxyprogesterone acetate which are associated with increased risk of coronary disease. Evidence that progesterone exerts protective effects on cardiovascular functions is briefly reviewed. The finding that progesterone administration decreases blood vessel vasoconstriction in several animal models within a few minutes suggests that rapid, nongenomic progesterone mechanisms are of physiological importance in regulating vascular tone. Rapid activation of second messenger pathways by progesterone has been observed in vascular endothelial and smooth muscle cells, resulting in alterations in endothelial nitric oxide synthase (eNOS) activity and calcium influx, respectively. Both nuclear progesterone receptors (PRs) and novel membrane progesterone receptors (mPRs) are candidates for the intermediaries in these rapid, cell-surface initiated progesterone actions in endothelial and smooth muscle vascular cells. PRs have been detected in both cell types. New data are presented showing mPRα, mPRβ and mPRγ are also present in human endothelial and smooth muscle vascular cells. Preliminary evidence suggests mPRs mediate rapid progestin signaling in these endothelial cells, resulting in down-regulation of cAMP production and increased nitric oxide synthesis. The role of mPRs in progesterone regulation of cardiovascular functions warrants further investigation.
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Affiliation(s)
- Peter Thomas
- University of Texas at Austin, 750 Channel View Drive, Port Aransas, TX 78373, USA.
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5
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Sarna MA, Hollenberg NK, Seely EW, Ahmed SB. Oral contraceptive progestins and angiotensin-dependent control of the renal circulation in humans. J Hum Hypertens 2009; 23:407-14. [PMID: 19158821 PMCID: PMC3712637 DOI: 10.1038/jhh.2008.148] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Oral contraceptive (OC) use is associated with increased intra-renal renin-angiotensin-aldosterone system (RAA System) activity and risk of nephropathy, though the contribution of progestins contained in the OC in the regulation of angiotensin-dependent control of the renal circulation has not been elucidated. Eighteen OC users (8 non-diabetic, 10 Type 1 diabetic) were studied in high salt balance, a state of maximal RAA System suppression. Progestational and androgenic activity of the progestin in each OC was standardized to that of the reference progestin norethindrone. Renal plasma flow (RPF) was measured by paraaminohippurate clearance at baseline and in response to angiotensin converting enzyme (ACE)-inhibition. There was a positive correlation between OC progestational activity and the RPF response to ACE-inhibition (r=0.52, p=0.03). Similar results were noted with OC androgenic activity (r=0.54, p=0.02). On subgroup analysis, only non-diabetic subjects showed an association between progestational activity and angiotensin-dependent control of the renal circulation (r=0.71, p=0.05 non-diabetic; r=0.14, p=0.7 diabetic; p=0.07 between groups). Similar results were noted with respect to androgenic activity (r=0.88, p=0.005 non-diabetic; r=−0.33, p=0.3 diabetic; p=0.002 between groups). Our results suggest that the OC progestin component is a significant influence on the degree of angiotensin-dependent control of the renal circulation, though these findings may not apply to women with diabetes.
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Affiliation(s)
- M A Sarna
- Department of Medicine, University of Calgary, Alberta, Canada
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Szmuilowicz ED, Adler GK, Ricchiuti V, Hopkins PN, Seely EW. Relationships between endogenous sex hormone concentrations and vascular function in postmenopausal women. J Clin Endocrinol Metab 2007; 92:4738-41. [PMID: 17895315 DOI: 10.1210/jc.2007-1471] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
CONTEXT Differences in postmenopausal endogenous sex hormone concentrations are associated with varying risks of a growing number of common diseases. The relationships between postmenopausal endogenous sex hormone concentrations and vascular function are not well understood. OBJECTIVE We examined in postmenopausal women the relationships between endogenous sex hormone concentrations and both blood pressure (BP) and renal vascular resistance (RVR), at baseline and in response to infused angiotensin II (AngII). SUBJECTS, INTERVENTIONS, AND MAIN OUTCOME MEASURES: A total of 34 hypertensive, postmenopausal women were studied in low-sodium and/or high-sodium balance. Serum estradiol, serum progesterone, BP, and RVR were measured at baseline. BP and RVR were remeasured after AngII infusion. RESULTS In low-sodium balance, the increases in systolic and diastolic BP in response to infused AngII were blunted with increased serum progesterone concentrations (P < 0.05). The increase in RVR in response to infused AngII was also blunted with increased serum progesterone concentrations (P < 0.005). The relationships between progesterone concentration and vascular response to AngII were independent of age, body mass index, and estradiol concentration. There were no significant correlations between estradiol concentration and BP or RVR response to AngII. There were no significant correlations between sex hormone concentrations and baseline BP or RVR. In high-sodium balance, there were no significant associations between sex hormone concentrations and vascular measures. CONCLUSIONS In postmenopausal women in low-sodium balance, the pressor and renovascular responses to AngII are blunted with increased endogenous progesterone concentrations. Our findings suggest a role for endogenous progesterone in modulating vascular function, even within the low postmenopausal range.
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Affiliation(s)
- Emily D Szmuilowicz
- Division of Endocrinology, Diabetes and Hypertension, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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Gard PR. The brain renin-angiotensin system: a target for novel antidepressants and anxiolytics. Drug Dev Res 2005. [DOI: 10.1002/ddr.20028] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Abstract
Polymorphisms of the renin-angiotensin system are associated with cardiovascular disorders, possibly as a consequence of increased brain angiotensin II activity. Within the brain, angiotensin controls blood pressure, fluid balance and hormone secretion; it also influences behaviour: reduction of central angiotensin function has both antidepressant-like and axiolytic-like actions. Evidence concerning the role of the renin-angiotensin system in learning and memory is contradictory, although more studies support the proposal that angiotensin reduces cognitive function. Studies of renin-angiotensin system genotype and psychological status have suggested an association between the angiotensin-converting enzyme deletion allele and age related cognitive decline, but a greater prevalence of the insertion allele in Alzheimer's disease. The deletion allele has also been associated with depressive illness, as has the M allele of the angiotensinogen gene although other studies have failed to replicate these findings. The role of the brain renin-angiotensin system in human psychopathology remains to be fully explored.
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Affiliation(s)
- Paul R Gard
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton BN2 4GJ, UK.
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Barbagallo M, Dominguez LJ, Licata G, Shan J, Bing L, Karpinski E, Pang PKT, Resnick LM. Vascular Effects of Progesterone : Role of Cellular Calcium Regulation. Hypertension 2001; 37:142-147. [PMID: 11208769 DOI: 10.1161/01.hyp.37.1.142] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
-Vascular actions of progesterone have been reported, independently of estrogen, affecting both blood pressure and other aspects of the cardiovascular system. To study possible mechanisms underlying these effects, we examined the effects of P in vivo in intact rats and in vitro in isolated artery and vascular smooth muscle cell preparations. In anesthetized Sprague-Dawley rats, bolus intravenous injections of P (100 µg/kg) significantly decreased pressor responses to norepinephrine (0.3 µg/kg). In vitro, progesterone (10(-8) to 10(-5) mmol/L) produced a significant, dose-dependent relaxation of isolated helical strips, both of rat tail artery precontracted with KCl (60 mmol/L) or arginine vasopressin (3 nmol/L), and of rat aorta precontracted with KCl (60 mmol/L) or norepinephrine (0.1 µmol/L). In isolated vascular smooth muscle cells, progesterone (5x10(-)(7) mol/L) reversibly inhibited KCl (30 mmol/L) -induced elevation of cytosolic-free calcium by 64.1+/-5.5% (P:<0.05), and in whole-cell patch-clamp experiments, progesterone (5x10(-6) mol/L) reversibly and significantly blunted L-type calcium channel inward current, decreasing peak inward current to 65.7+/-4.3% of the control value (P:<0.05). Our results provide evidence that progesterone is a vasoactive hormone, inhibiting agonist-induced vasoconstriction. The data further suggest that progesterone effects on vascular tissue may, at least in part, be mediated by modulation of the L-type calcium channel current activity and, consequently, of cytosolic-free calcium content.
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Affiliation(s)
- Mario Barbagallo
- Institute of Internal Medicine and Geriatrics (M.B., L.J.D., G.L.), University of Palermo, Palermo, Italy
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Makino I, Shibata K, Makino Y, Kangawa K, Kawarabayashi T. Potentiation of the hypotensive effect of adrenomedullin in pregnant rats. Eur J Pharmacol 1999; 385:129-36. [PMID: 10607868 DOI: 10.1016/s0014-2999(99)00670-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The hypotensive effect of adrenomedullin, a potent vasodilator peptide, was examined in conscious pregnant (6, 13 and 20 days of pregnancy) and non-pregnant rats. The intravenous administration of adrenomedullin (0.01-3.0 nmol/kg) produced a dose-dependent depressor response in pregnant and non-pregnant rats. At low doses (0.01-0.1 nmol/kg), the maximum decrease in blood pressure was significantly higher in pregnant rats (20 days pregnant) than in non-pregnant rats. At high doses, no significant difference was observed between the two groups. Furthermore, the administration of adrenomedullin did not significantly affect the basal mean blood pressure (MBP) at any dose when compared to the non-pregnant group at 6 and 13 days of pregnancy. In the ovariectomized rats, the depressor responses in 17beta-estradiol-treated, progesterone-treated and 17beta-estradiol+progesterone-treated rats were not significantly different from that in the control rats, suggesting that the augmented effect on the depressor response to adrenomedullin in pregnant rats may not be due to hormonal changes during pregnancy. The adrenomedullin receptor mRNA level of the descending thoracic aorta was significantly higher in the late-pregnancy rats (20 days of pregnancy). However, the levels did not show any difference between the early-pregnant rats (6 and 13 days of pregnancy) and the non-pregnant rats. These findings suggested that the changes in the depressor response to adrenomedullin which occur at term in pregnant rats may be mediated by changes of adrenomedullin receptor gene expression rather than by sex hormones.
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Affiliation(s)
- I Makino
- Department of Obstetrics and Gynecology, School of Medicine, Fukuoka University, Fukuoka, Japan
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Makino I, Makino Y, Kangawa K, Shibata K. Attenuated hypotensive response to proadrenomedullin N-terminal 20 peptide in pregnant rats: modulation by steroid hormones. Peptides 1999; 20:1521-5. [PMID: 10698130 DOI: 10.1016/s0196-9781(99)00165-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The hypotensive effect of proadrenomedullin N-terminal 20 peptide (PAMP) was examined in conscious pregnant (8, 14, and 20 days of pregnancy) and nonpregnant rats. Intravenous administration of PAMP (3-60 nmol/kg) produced a dose-dependent depressor response in both pregnant and nonpregnant rats. However, the maximum decrease in blood pressure was significantly attenuated in pregnant rats in mid- and late-gestation (14 and 20 days), but not in early gestation (8 days), than in nonpregnant rats. In ovariectomized rats, the depressor responses in 17beta-estradiol (E2)-treated, progesterone (P)-treated, and E2+P-treated rats were significantly attenuated compared with the control rats. We also demonstrated that treatment of sex hormones reduces the depressor response to PAMP in 8-day pregnant rats. In addition, we showed that treatment of sex hormone receptor antagonists partially prevents the attenuation of the depressor response to PAMP in 20 day pregnant rats. These findings suggested that the hypotensive response to PAMP was more attenuated in pregnant rats in mid- and late-gestation than in nonpregnant rats, and that the changes in depressor response that occur at term in pregnant rats may be mediated by sex hormones. PAMP may play some important role in cardiovascular regulation during pregnancy.
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Affiliation(s)
- I Makino
- Department of Obstetrics and Gynecology, School of Medicine, Fukuoka University, Japan
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12
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Kau MM, Lo MJ, Tsai SC, Chen JJ, Lu CC, Lin H, Wang SW, Wang PS. Effects of estradiol on aldosterone secretion in ovariectomized rats. J Cell Biochem 1999; 73:137-44. [PMID: 10088732 DOI: 10.1002/(sici)1097-4644(19990401)73:1<137::aid-jcb15>3.0.co;2-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The effects and action mechanisms of estradiol on aldosterone secretion in female rats were studied. Replacement of estradiol benzoate (EB) increased the levels of plasma estradiol and aldosterone in ovariectomized (Ovx) rats. The aldosterone release from zona glomerulosa (ZG) cells was higher in EB-treated rats than in oil-treated animals. EB treatment potentiated the responses of aldosterone release to adrenocorticotropic hormone (ACTH), forskolin (FSK), and 8-bromoadenosine 3',5'-cyclic monophosphate (8-Br-cAMP). Administration of EB in vivo did not alter cAMP production in response to ACTH or FSK. Although angiotensin II (Ang II) increased aldosterone secretion by rat ZG cells, the stimulatory effect of Ang II on the release of aldosterone was not altered by EB treatment. The conversions of [3H]-deoxycorticosterone to [3H]-corticosterone and [3H]-corticosterone to [3H]-aldosterone in EB-treated groups were greater than those in the oil-treated group. These results suggest that estradiol increases aldosterone secretion in part through the mechanisms involving the activation of the post-cAMP pathway, 11beta-hydroxylase and aldosterone synthase activity.
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Affiliation(s)
- M M Kau
- Department of Physiology, School of Life Science, National Yang-Ming University, Taipei, Taiwan, Republic of China
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13
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Abstract
Nonrandomized trials of postmenopausal estrogen replacement have shown a benefit in the prevention of coronary artery disease. Less clear are the specific mechanisms by which this occurs. Estrogen has beneficial effects on the lipid profile, with significant elevations in high density lipoprotein cholesterol and reductions in low density lipoprotein cholesterol reported. Also, antioxidant properties have been ascribed to estrogen. In addition, estrogen has been shown to prevent paradoxic vasoconstriction in atherosclerotic coronary arteries after acetylcholine and may have calcium channel-blocking and alpha2-inhibiting properties. Other proposed mechanisms of cardiovascular protection include reductions in serum fibrinogen and increases in prostacyclin biosynthesis. There is some evidence that cardiovascular biomechanics may be mildly depressed after menopause and that estrogen may normalize these changes by increasing ventricular contractility and, possibly, relaxation. Far less is known about the cardiovascular effects of progesterone, but overall it does not appear that the less androgenic progestins substantially modify the effects of estrogen. Because more women > 50 years old die of cardiovascular disease than any other cause, further clinical investigations of the risks and benefits of estrogen replacement and combined estrogen and progesterone therapy are clearly needed.
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Affiliation(s)
- S A Samaan
- Department of Medicine, University of New Mexico Health Sciences, Albuquerque 87131, USA
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Ito M, Nakamura T, Yoshimura T, Koyama H, Okamura H. 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. Am J Obstet Gynecol 1992; 166:1249-53. [PMID: 1566780 DOI: 10.1016/s0002-9378(11)90617-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
OBJECTIVE This study is a survey of the determinants of refractoriness to the pressor effects of angiotensin II during normal pregnancy. STUDY DESIGN 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. CONCLUSION 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.
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Affiliation(s)
- M Ito
- Department of Obstetrics and Gynecology, Kumamoto University Medical School, Japan
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Lumbers ER. Effects on sheep blood pressure of treatment with angiotensin, steroids and salt. Clin Exp Pharmacol Physiol 1990; 17:315-9. [PMID: 2347121 DOI: 10.1111/j.1440-1681.1990.tb01327.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
1. Angiotensin II (AII, 0.22 microgram/min) infused for 7-14 days, into adult unanaesthetized wethers, caused a rise in blood pressure of 7 +/- 3/7 +/- 3 mmHg (mean +/- s.e.m.) from control values of 90 +/- 5/54 +/- 3 mmHg (P less than 0.05, n = 11). Cardiac output and pulse interval were not affected. A high salt intake had no effect on blood pressure, cardiac output and pulse interval, nor did it potentiate the action of AII. 2. Ethinyl oestradiol (EE, 20 mg/week) caused a small fall in systolic and diastolic pressure of 6 +/- 3/6 +/- 5 mmHg (n = 7, P less than 0.1, P less than 0.05). When AII (0.22 microgram/min) was given with EE, it still caused a significant rise in blood pressure (P less than 0.01). The synthetic progestin (1 mg of norethisterone [NE] for 8-18 days) plus a high salt diet had no effect on arterial pressure and cardiac output but pulse interval rose significantly (P less than 0.05). 3. Therefore the reduction in vascular reactivity to angiotensin seen in human pregnancy is probably not related to high levels of oestrogen. Further, NE combined with a high salt diet does not cause hypertension in sheep.
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Affiliation(s)
- E R Lumbers
- School of Physiology and Pharmacology, University of New South Wales, Kensington, Sydney, Australia
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