Pulmonary embolism in pregnancy.

Venous thromboembolism (VTE) is a major cause of maternal morbidity and mortality during pregnancy or early after delivery, remaining a diagnostic and therapeutic challenge in both states. The absolute incidence of pregnancy-associated VTE has been reported as 1 in 1,000 to 1 in 2,000 deliveries. With 5-6 million new births computed in Europe in 2010, the potential clinical relevance of diagnosing and treating gravidic VTE is immediately evident. Fivefold higher in a pregnant as compared with a non-pregnant woman, VTE risk is also higher in postpartum than antepartum period. Ranked absolute and relative thrombotic risk may be described in the several thrombophilic conditions experienced by women at risk, according to which specific prophylactic and therapeutic recommendations have been formulated by recent guidelines. The main purpose of the present review article was to emphasize the most recent findings and recommendations in diagnostic strategies, discussing thrombophilic risk evaluation, as well as risks and benefits of various diagnostic techniques for both mother and fetus.

Chromosomal mapping of quantitative trait loci contributing to stroke in a rat model of complex human disease.

Stroke is a complex disorder with a poorly understood multifactorial and polygenic aetiology. We used the stroke-prone spontaneously hypertensive rat (SHRSP) as a model organism, mated it with the stroke-resistant spontaneously hypertensive rat (SHR) and performed a genome-wide screen in the resultant F2 cohort where latency until stroke, but not hypertension (a major confounder) segregated. We identified three major quantitative trait loci, STR1-3, with lod scores of 7.4, 4.7 and 3.0, respectively, that account for 28% of the overall phenotypic variance. STR2 colocalizes with the genes encoding atrial and brain natriuretic factor, peptides with important vasoactive properties. Our results demonstrate the existence of primary, blood pressure-independent genetic factors predisposing to a complex form of stroke.

Renin as a biomarker of cardiovascular disease in clinical practice.

The search for novel circulating blood biomarkers as predictors of cardiovascular (CV) risk and prognosis is a continuing field of interest in clinical medicine. Biomarkers from several pathophysiological pathways, including markers of organ damage, of inflammation, of the atherosclerotic process and of the coagulation pathway, have been investigated in the last decades. A particular interest has been raised for neurohormonal factors. The role of the activation of the sympathetic system and the renin-angiotensin-aldosterone system (RAAS) in the development of CV diseases has been extensively explored. Renin is the first limiting step of the RAAS and its role as a biomarker to improve CV risk stratification still remains a topic of debate. Several studies have shown that elevated plasma renin activity is associated with increased morbidity and mortality in patients with CV disease. The aim of this paper is to critically evaluate the evidence on the role of renin as a biomarker of CV risk and prognosis. With the new advances of pharmacological treatment acting on the RAAS, the effect of elevated levels of renin on the prognosis of these patients becomes even more intriguing.

Failure of atrial natriuretic factor to increase with saline load in patients with dilated cardiomyopathy and mild heart failure.

To investigate whether the response of atrial natriuretic factor (ANF) to volume expansion is impaired in the early stages of dilated cardiomyopathy, the effects of saline load (SL; 0.25 ml/kg.min for 120 min) were assessed in 12 patients with dilated cardiomyopathy and asymptomatic to mildly symptomatic heart failure (HF) and in nine normal subjects (N). SL increased plasma ANF levels in N (from 14.3 +/- 2 to 19.5 +/- 3 and 26 +/- 4 pg/ml, at 60 and 120 min, respectively, P less than 0.001), but not in HF (from 42.9 +/- 9 to 45.9 +/- 9 and 43.9 +/- 8 pg/ml). Left ventricular end-diastolic volume (LVEDV) and stroke volume were increased (P less than 0.001) by SL in N but not in HF. Urinary sodium excretion (UNaV) increased in N more than in HF during SL, whereas forearm vascular resistance (FVR) did not change in N and increased in HF (P less than 0.001). In five HF patients SL was performed during ANF infusion (50 ng/kg, 5 ng/kg.min) that increased ANF levels from 37.1 +/- 10 to 146 +/- 22 pg/ml. In this group, SL raised both LVEDV (P less than 0.01) and ANF (P less than 0.05), whereas FVR did not rise. In addition, the UNaV increase and renin and aldosterone suppressions by SL were more marked than those observed in HF under control conditions. Thus, in patients with dilated cardiomyopathy and mild cardiac dysfunction, plasma ANF levels are not increased by volume expansion as observed in N. The lack of ANF response is related to the impaired cardiac adaptations. The absence of an adequate increase of ANF levels may contribute to the abnormal responses of HF patients to saline load.

Association and cosegregation of stroke with impaired endothelium-dependent vasorelaxation in stroke prone, spontaneously hypertensive rats.

While hypertension is a major risk factor for stroke, it is not its sole determinant. Despite similar blood pressures, spontaneously hypertensive rats (SHR) do not share the predisposition to cerebrovascular disease typical of stroke-prone spontaneously hypertensive rats (SHRSP). We investigated vascular function in male SHR and SHRSP as well as in SHRSP/SHR-F2 hybrid animals. Animals were maintained on the appropriate dietary regimen necessary for the manifestation of stroke. Among the hybrid animals, a group of stroke-prone and a group of stroke-resistant rats were selected. Blood pressure was similar in all groups. Endothelium-independent vascular reactivity tested on isolated rings of thoracic aorta and basilar artery after death showed similar contractile and dilatory responses to serotonin and nitroglycerin, respectively, in all groups. In contrast, endothelium-dependent relaxation, in response to acetylcholine or substance P, was markedly reduced in SHRSP compared with SHR. Similarly, reduced vasodilatory responses were present in aortae of F2 rats that had suffered a stroke when compared with SHR or F2 rats resistant to stroke. The observed association and cosegregation of stroke with significant and specific impairment of endothelium-dependent vasorelaxation among SHRSP and stroke-prone F2 hybrids, respectively, suggest a potential causal role of altered endothelium-dependent vascular relaxation in the pathogenesis of stroke.

Atrial natriuretic peptide (ANP) gene promoter variant and increased susceptibility to early development of hypertension in humans.

Previous evidence supports a role of atrial natriuretic peptide (ANP) as a candidate gene for hypertension. We characterized an ANP gene promoter variant, which has been associated with lower peptide levels, in a sample of young male subjects from Southern Italy (n=395, mean age=35.2+/-2 years) followed up for 28 years. In this cohort, the ANP gene variant was associated with early blood pressure increase and predisposition to develop hypertension.

Altered structure, regulation, and function of the gene encoding the atrial natriuretic peptide in the stroke-prone spontaneously hypertensive rat.

Through the genotype/phenotype cosegregation analysis of an F(2) intercross, from the crossbreeding of stroke-prone spontaneously hypertensive rats (SHRSP) and stroke-resistant spontaneously hypertensive rats (SHR), we previously identified a quantitative trait locus for stroke on rat chromosome 5 (STR2) that colocalized with the genes encoding atrial and brain natriuretic peptides (ANP and BNP) and conferred a stroke-delaying effect. To further characterize ANP and BNP as candidates for stroke, we performed additional studies. Comparative sequence analysis revealed point mutations in both the coding and regulatory regions of ANP, whereas no interstrain differences were found for BNP. In in vitro studies in COS-7 and AtT-20 cells that were performed to test the relevance of a G-->A substitution at position 1125, a Gly-->Ser transposition in the SHRSP pro-ANP peptide resulted in different posttranslational processing of the SHRSP ANP gene product that was also associated with higher cGMP production (P<0.05). Furthermore, an analysis of a 5' end mutation affecting a PEA2 regulatory binding site in the 5' untranslated regulatory sequence of SHRSP ANP demonstrated a significantly lower ANP promoter activation in endothelial cells (P<0.05 versus the SHR ANP). In addition, the expression of ANP was significantly reduced in the brain, but not in the atria, of SHRSP compared with SHR (P<0.0001). No differences were detected with regard to BNP expression. The present results reveal substantial differences in ANP, but not BNP, structure and product among SHR and SHRSP, which supports a role of ANP in the pathogenesis of stroke in the SHRSP animal model.

Molecular cloning and expression of rat kallistatin gene.

We have previously purified and cloned human kallistatin and rat kallikrein-binding protein (RKBP), which are tissue kallikrein inhibitors belonging to the serine proteinase inhibitor superfamily. In this study, we have cloned and sequenced the gene encoding rat kallistatin with Phe-Phe-Ser-Ala-Gln at positions P2-P3', which is identical to the reactive center of human kallistatin. Rat kallistatin is highly similar to human kallistatin, sharing 68% and 57% sequence identity at the cDNA and the amino acid levels. The rat kallistatin gene exists in a single copy and is located on chromosome 6. An SphI RFLP is found between SHR and WKY rats at or near the rat kallistatin gene locus. Two amino acid polymorphisms of the rat kallistatin gene between these two strains were found by sequence analysis. A candidate promoter in the 5'-flanking region (109 bp) of the rat kallistatin gene has been identified by reporter assays. The expression of rat kallistatin in the liver is growth-dependent and down-regulated during acute phase inflammation. Recombinant rat kallistatin produced in E. coli is able to bind to tissue kallikrein, and the interaction is inhibited by heparin. These characteristics define rat kallistatin as the counterpart of human kallistatin.

The gene encoding atrial natriuretic peptide and the risk of human stroke.

BACKGROUND: Recent evidence from an animal model of stroke, the stroke-prone spontaneously hypertensive rat, implicated the gene encoding atrial natriuretic peptide (ANP) as a possible candidate contributing to the likelihood of experiencing a stroke. The purpose of the present study was to investigate the role of ANP in the pathogenesis of cerebrovascular accidents in humans. METHODS AND RESULTS: We investigated 2 previously known markers at ANP, G1837A and T2238C, for their possible association with the occurrence of stroke. This was the largest matched case-controlled sample studied thus far; the sample was drawn from a large prospective study (the Physician's Health Study). When assuming a dominant mode of inheritance, a statistically significant positive association was observed for the 1837A allele, indicating an odds ratio of 1.64 (95% confidence interval, 1.01 to 2.65) for stroke. This observation led to the discovery of a new molecular variant in exon 1, G664A, which was responsible for a valine-to-methionine substitution in the proANP peptide. This mutation, which was in linkage disequilibrium with the G1837A marker, was associated with the occurrence of stroke (odds ratio, 2.0; 95% confidence interval, 1.17 to 3.19; P=0.01). CONCLUSIONS: Our findings suggest that molecular variants of the ANP gene may represent an independent risk factor for cerebrovascular accidents in humans. The strong parallelism to the experimental data obtained in the stroke-prone animal model provides assurance for the relevance of our observation.

Angiotensin II Receptor Blocker Neprilysin Inhibitor (ARNI): New Avenues in Cardiovascular Therapy.

The burden of cardiovascular disease (CVD) is continuously and progressively raising worldwide. Essential hypertension is a major driver of cardiovascular events, including coronary artery disease, myocardial infarction, ischemic stroke and congestive heart failure. This latter may represent the final common pathway of different cardiovascular diseases, and it is often mediated by progressive uncontrolled hypertension. Despite solid advantages derived from effective and sustained blood pressure control, and the widespread availability of effective antihypertensive medications, the vast majority of the more than 1 billion hypertensive patients worldwide continue to have uncontrolled hypertension. Among various factors that may be involved, the abnormal activation of neurohormonal systems is one consistent feature throughout the continuum of cardiovascular diseases. These systems may initiate biologically meaningful "injury responses". However, their sustained chronic overactivity often may induce and maintain the progression from hypertension towards congestive heart failure. The renin-angiotensin-aldosteron system, the sympathetic nervous system and the endothelin system are major neurohormonal stressor systems that are not only able to elevate blood pressure levels by retaining water and sodium, but also to play a role in the pathophysiology of cardiovascular diseases. More recently, the angiotensin receptor neprilysin inhibitor (ARNI) represents a favourable approach to inhibit neutral endopeptidase (NEP) and suppress the RAAS via blockade of the AT1 receptors, without the increased risk of angioedema. LCZ696, the first-in-class ARNI, has already demonstrated BP lowering efficacy in patients with hypertension, in particular with respect to systolic blood pressure levels, improved cardiac biomarkers, cardiac remodelling and prognosis in patients with heart failure. This manuscript will briefly overview the main pathophysiological and therapeutic aspects of ARNI in the clinical management of hypertension and heart failure.

C2238/αANP modulates apolipoprotein E through Egr-1/miR199a in vascular smooth muscle cells in vitro.

Subjects carrying the T2238C ANP gene variant have a higher risk to suffer a stroke or myocardial infarction. The mechanisms through which T2238C/αANP exerts detrimental vascular effects need to be fully clarified. In the present work we aimed at exploring the impact of C2238/αANP (mutant form) on atherosclerosis-related pathways. As a first step, an atherosclerosis gene expression macroarray analysis was performed in vascular smooth muscle cells (VSMCs) exposed to either T2238/αANP (wild type) or C2238/αANP. The major finding was that apolipoprotein E (ApoE) gene expression was significantly downregulated by C2238/αANP and it was upregulated by T2238/αANP. We subsequently found that C2238/αANP induces ApoE downregulation through type C natriuretic peptide receptor (NPR-C)-dependent mechanisms involving the upregulation of miR199a-3p and miR199a-5p and the downregulation of DNAJA4. In fact, NPR-C knockdown rescued ApoE level. Upregulation of miR199a by NPR-C was mediated by a reactive oxygen species-dependent increase of the early growth response protein-1 (Egr-1) transcription factor. In fact, Egr-1 knockdown abolished the impact of C2238/αANP on ApoE and miR199a. Of note, downregulation of ApoE by C2238/αANP was associated with a significant increase in inflammation, apoptosis and necrosis that was completely rescued by the exogenous administration of recombinant ApoE. In conclusion, our study dissected a novel mechanism of vascular damage exerted by C2238/αANP that is mediated by ApoE downregulation. We provide the first demonstration that C2238/αANP downregulates ApoE in VSMCs through NPR-C-dependent activation of Egr-1 and the consequent upregulation of miR199a. Restoring ApoE levels could represent a potential therapeutic strategy to counteract the harmful effects of C2238/αANP.

Dexamethasone-inhibitable stimulation of plasma prorenin by ketamine in cats.

Plasma prorenin in humans is derived from both renal and extrarenal sources, but in the cat most plasma prorenin is normally of renal origin. Sodium depletion and beta-adrenergic blockade can increase plasma prorenin in cats, but the effects of sedatives and glucocorticoids are unknown. We examined the effect of ketamine, a centrally acting nonbarbiturate anesthetic, and of the glucocorticoid dexamethasone on plasma prorenin and renin. Intramuscular injection of ketamine (20 mg/kg, three times a day) for 4 days increased plasma prorenin slowly and consistently, from 7.4 +/- 1.4 (+/- SEM) to 11.4 +/- 2.2, 17.1 +/- 2.5, 20.2 +/- 3.0, and 29.2 +/- 3.4 ng/ml.h (P less than 0.001) on days 1, 2, 3, and 4, respectively, without any effect on plasma active renin. Plasma renin substrate and cortisol were also unchanged. Bilateral nephrectomy reduced both baseline and stimulated plasma prorenin to undetectable levels. Treatment with alpha 1-blocker, beta 1-blocker, angiotensin-converting enzyme inhibitor, or Ca2+ antagonist did not affect the rise in prorenin induced by ketamine, but dexamethasone completely blocked the response. In contrast, dexamethasone alone had little effect on plasma prorenin. These results demonstrate that repetitive ketamine administration selectively increases plasma prorenin, suggesting that renal prorenin secretion may be regulated independently of active renin. Blockade of stimulated, but not baseline, plasma prorenin by dexamethasone is consistent with a negative effect of glucocorticoids on the regulatory elements of the renin gene.

Influence of hypercholesterolemia on adrenal steroid metabolism and electrolyte balance in spontaneously hypertensive rats.

Hypercholesterolemia and hypertension are frequently associated risk factors for cardiovascular diseases. The interactions between hypercholesterolemia and the regulatory mechanisms of blood pressure are poorly understood. In this study we investigated the effects of hypercholesterolemia on salt metabolism and its hormonal control mechanisms in spontaneously hypertensive rats (SHR). Six-week-old SHR were randomly assigned to either a high (1%) cholesterol diet or a matched regular diet for 6 weeks, followed by a 2-week dietary washout. A group of normotensive Wistar-Kyoto rats received the high cholesterol diet and was used as a control. Plasma cholesterol increased significantly (P < 0.001) in both cholesterol-fed SHR and Wistar-Kyoto rats. Blood pressure was unaffected by 6 weeks of a high cholesterol diet. Hypercholesterolemia caused a significant increase in aldosterone (by analysis of variance: F = 8.40; P < 0.01) associated with a significant decrease in corticosterone (F = 4.64; P < 0.05) in the SHR, but not in the normotensive rats. In addition, in the cholesterol-fed SHR, urinary sodium excretion was reduced (P < 0.01), and the urinary potassium/sodium ratio was increased (P < 0.01) compared to those in the remaining groups of rats. The hormonal and urinary differences between the hypertensive subgroups were not detectable after withdrawal of cholesterol. These results demonstrate that diet-induced hypercholesterolemia specifically promotes reversible mineralocorticoid accumulation and sodium retention in SHR.

Modulatory role of angiotensin-II in the secretion of atrial natriuretic factor in rabbits.

This study was designed to investigate whether the increase in circulating atrial natriuretic factor (ANF) levels produced by angiotensin II (Ang II) is a consequence of the hemodynamic changes or whether it occurs also in the absence of pressor changes. For this purpose in anesthetized and awake rabbits we evaluated the effects of Ang II (0.1 micrograms/kg.min) alone or during the simultaneous infusion of sodium nitroprusside (NP) at a dose titrated to abolish the pressor effects. Systemic blood pressure increased from 76 +/- 4 to 113 +/- 5 mm Hg (P less than 0.001) during Ang II and from 76 +/- 2 to 75 +/- 3 mm Hg (P = NS) during Ang II plus NP. The alpha-adrenergic agonist phenylephrine, used as a control, raised blood pressure from 65 +/- 2 to 101 +/- 8 mm Hg (P less than 0.001), and its pressor effect was abolished by the concomitant infusion of NP (64 +/- 2 to 61 +/- 1 mm Hg; P = NS). The increase in plasma ANF levels produced by Ang II alone (from 36.5 +/- 5 to 237 +/- 57 pg/ml; P less than 0.001) was not different from that observed during Ang II plus NP (from 46 +/- 10 to 207 +/- 88 pg/ml; P less than 0.001). In contrast, the stimulatory effect on ANF release of phenylephrine (from 56.1 +/- 9 to 202 +/- 40 pg/ml; P less than 0.001) was completely abolished when its pressor effects were prevented by the combined infusion of NP (from 58.5 +/- 15 to 42.3 +/- 10 pg/ml; P = NS). These results show that the stimulatory effect of Ang II on ANF release can be clearly dissociated from its pressor effect, whereas the increase in plasma ANF levels caused by phenylephrine is strictly related to its hemodynamic effect. Therefore, Ang II is capable of modulating ANF secretion in a manner that is independent of its pressor actions. In addition, our results suggest that ANF release is not solely linked to myocyte stretch.

Salt-regulating hormones in young normotensive obese subjects. Effects of saline load.

To investigate whether the response of salt-regulating hormones to volume expansion is impaired in obese subjects, we assessed the effects of saline load (0.25 mL/kg.min.120 min) in 9 young, healthy, normotensive obese subjects (body mass index, > 30 kg/m2) and in 10 lean control subjects (body mass index, < 25 kg/m2) matched for age, gender, height, and mean blood pressure. Hematocrit, plasma renin activity (PRA), plasma aldosterone (PA), atrial natriuretic factor (ANF), and urinary sodium excretion (UNaV) were evaluated. Saline load increased ANF levels significantly (P < .001) in lean subjects at both 60 and 120 minutes, whereas they decreased in obese subjects. Such decreases became significant (P < .01) at 120 minutes. Suppression of PRA and PA by saline load were more marked in lean than obese subjects. Hematocrit decreased in both groups, and UNaV increased more in lean than obese subjects during saline load. Comparisons of percent changes in ANF, PRA, and PA after saline load showed that the responses of lean and obese subjects were significantly different (P < .001 for ANF at both 60 and 120 minutes; P < .05 for PRA and PA at both 60 and 120 minutes). In conclusion, the lack of ANF response and the reduced suppression of PRA and PA to saline load indicate a dysfunction of these systems in obese subjects. This alteration may be involved in the higher susceptibility of obese subjects to developing hypertension.

Highest concentrations of prorenin and human chorionic gonadotropin in gestational sacs during early human pregnancy.

Prorenin is not only the biosynthetic precursor of renin; under certain circumstances in vitro prorenin exhibits reversible intrinsic renin activity and can form angiotensin from renin substrate with or without cleavage of the prosequence. Prorenin is the predominant form of renin synthesized by reproductive organs (ovary, chorion laeve of the placenta, uterine decidua). Its plasma concentrations increases 10-fold throughout pregnancy to 10-100 times that of renin; amniotic fluid prorenin concentration is even higher. No data are available of gestational fluid prorenin concentrations during early pregnancy. For the first 10 weeks there are two gestational cavities; the chorionic cavity then disappears and the smaller amniotic cavity becomes predominant. In this study we measured prorenin, renin, renin substrate and hCG in fluid aspirated from gestational sacs during the first trimester of gestation (predominantly chorionic) and during the second and third trimesters (amniotic). Seventeen patients had amniocentesis during the second or third trimester. Nine patients underwent selective abortion of multiple pregnancy at 7-12 weeks gestation. One patient underwent surgery at 5 5/7 weeks (26 days after conception) for a tubal pregnancy. Second and third trimester amniotic fluid prorenin maximum velocity (Vmax) (16 and 3 sacs, respectively) averaged 6,100 +/- 1,700 (SD) and 1,930 +/- 760 ng/mL.h, respectively (i.e. 1,700 and 540 ng/L.s). In gestational fluid collected before 8 weeks, prorenin Vmax was 10-fold higher, averaging 62,500 +/- 40,000 ng/mL.h (17,000 ng/L.s). The concentration was 140,000 ng/mL.h (39,000 ng/L.s) in the 5 5/7 week tubal pregnancy. In sharp contrast, at 10-12 weeks gestation (n = 3) prorenin Vmax was only 260 +/- 114 ng/mL.h (72 ng/L.s); human CG was also highest before 8 weeks (276,500 +/- 110,900 IU/L) and lowest at 10-12 weeks (1210 +/- 540 IU/L) with intermediate levels occurring later in pregnancy. This study shows that the highest biological levels of prorenin yet detected (close to 1 micrograms protein/mL) occur in gestational sacs in early pregnancy, consistent with a role for the renin-angiotensin system in embryonic development or placentation.

Role of the alpha-, beta-, and gamma-subunits of epithelial sodium channel in a model of polygenic hypertension.

The pathophysiological basis of Liddle's syndrome, a rare autosomal dominant form of arterial hypertension, has been found to rest on missense mutations or truncations of the beta- and gamma-subunits of the epithelial sodium channel. The hypothesis has been advanced that molecular variants of these genes might also contribute to the common polygenic forms of hypertension. We tested this hypothesis by performing a cosegregation study in a reciprocal cross between the stroke-prone spontaneously hypertensive rat (SHRSPHD) and a Wistar-Kyoto rat (WKY-1HD) reference strain. We carried out genetic mapping and chromosomal assignment of the alpha-, beta-, and gamma-subunits of the epithelial sodium channel using both linkage analysis and fluorescent in situ hybridization techniques. We demonstrate that in the rat, the beta- and gamma-subunits, as in humans, are in close linkage; they map to rat chromosome 1 and cosegregate with systolic pressure after dietary NaCl (logarithm of the odds [LOD] score, 3.7), although the peak LOD score of 5.0 for this quantitative trait locus was detected 4.4 cM away from the beta-/gamma-subunit locus. The alpha-subunit was mapped to chromosome 4 and exhibited no linkage to blood pressure phenotype. Comparative analysis of the complete coding sequences of all three subunits in the SHRSPHD and WKY-1HD strains revealed no biologically relevant mutations. Furthermore, Northern blot comparison of mRNA levels for all three subunits in the kidney showed no differences between SHRSPHD and WKY-1HD. Our results fail to support a material contribution of the epithelial sodium channel genes to blood pressure regulation in this model of polygenic hypertension.

Relationship of follicular fluid prorenin to oocyte maturation, steroid levels, and outcome of in vitro fertilization.

Prorenin (PR) is present in high concentrations in the follicular fluid (FF) of the preovulatory follicle. It is the predominant form of renin detected in FF. Its biosynthesis and secretion from the ovary are regulated by gonadotropins. In the present study we measured PR and steroid levels in FF from 136 follicles. Follicular fluids were obtained, 36 h after hCG injection, from 41 ovarian-stimulated patients who underwent follicle puncture and oocyte retrieval for in vitro fertilization. We related FF PR to steroid levels and to the stage of oocyte-cumulus complex maturation. PR levels in 62 FF containing mature healthy fertilized oocytes averaged 2620 +/- 157 (+/- SE) ng/mL.h (728 +/- 44 ng/L.s; range, 1020-6880 ng/mL.h, 283-1911 ng/L.s). A subgroup of 16 of these follicles containing mature oocytes were from 7 women who conceived, in which PR levels spanned only the lower range from 1030-2720 ng/mL.h (286-756 ng/L.s). No patient conceived with FF PR above 2800 ng/mL.h (778 ng/L.s), yet one third of all mature follicles were above this range. Lower levels of PR were detected in FF containing immature oocytes (germinal vesicle stage) associated with either compact (1665 +/- 480 ng/mL.h; 463 +/- 133 ng/L.s; n = 22; P less than 0.02) or expanded (1785 +/- 193 ng/mL.h; 496 +/- 54 ng/L.s; n = 24; P less than 0.005) cumulus mass; a subgroup (n = 5) of follicles with immature oocytes and compact cumulus had very high levels of FF PR, ranging from 3830-7520 ng/mL.h (1064-2089 ng/L.s), while the remainder had levels less than 1300 ng/mL.h (361 ng/L.s). Progesterone and estradiol (E2) were lower in FF surrounding immature oocytes associated with compact (P less than 0.005) or expanded (P less than 0.02) cumulus, than in those containing mature oocytes. Testosterone (T) and androstenedione were measured in only a fraction of the samples; there were no apparent differences between follicles containing mature and immature oocytes. However, T and androstenedione levels were high in the subgroup of follicles containing immature oocytes and very high levels of PR. Of the hormones measured, T revealed the most striking relationship with PR (r = 0.62; n = 49; P less than 0.001).(ABSTRACT TRUNCATED AT 400 WORDS)

Estradiol- and progesterone-related increases in the renin-aldosterone system: studies during ovarian stimulation and early pregnancy.

To investigate the degree to which endogenous increases in estradiol (E2) and progesterone (P4) are associated with changes in the renin system, we studied eight patients undergoing ovarian stimulation for in vitro fertilization (FSH/human menopausal gonadotropin or clomiphene citrate for 5-11 days, followed by hCG). Three conceived and were followed for up to 62 days after hCG treatment. The others were followed until the end of the luteal phase. During the follicular phase, E2 increased 10-fold, PRA increased 2-fold, and absolute levels of E2 and P4 were positively correlated (r = 0.63; P < 0.05). After ovulation, which was induced by hCG, E2 fell by 50% (day 7), but there was a 50-fold increase in P4 and a further 5-fold increase in PRA. By day 14, E2 increased again in the women who conceived, to levels even higher than those in the follicular phase, and both P4 and PRA increased 2- to 3-fold between days 7 and 14. In contrast, E2, P4, and PRA returned toward baseline levels in the nonpregnant women. On day 21, E2, P4, and PRA remained very high in the pregnant women [E2, 2297 +/- 255 pg/mL (8430 pmol/L); P4, 103 +/- 22 pg/mL (328 pmol/L); PRA, 33 +/- 8 ng/mL.h (9.17 ng/L.s)]. During the luteal phase and early pregnancy, there was a positive relationship between PRA and P4 (r = 0.68; P < 0.05). There was also a positive relationship between PRA and E2 (r = 0.54; P < 0.05); compared to the follicular phase level, PRA was 4-fold higher in the luteal phase at any E2 level. Like renin, urinary aldosterone excretion (UA) increased 5-fold during the luteal phase (day 7) and by a further 3-fold between days 7 and 21 in the pregnant women, reaching very high levels [135 +/- 28 micrograms/day (375 nmol/day); n = 3]. PRA and UA positively correlated (r = 0.59; P < 0.08). Plasma angiotensinogen increased from 2146 +/- 283 ng angiotensin-I/mL (n = 8) to 3682 +/- 607 (n = 8) on day 7 and to 5353 +/- 799 (n = 3) on day 21. Urinary sodium excretion did not fall, and urinary potassium did not increase in coordination with the changes in renin and aldosterone. There was no hypokalemia. These results demonstrate marked increases in plasma renin and UA in coordination with increases in plasma E2 and P4 during ovarian stimulation and early pregnancy, and coordinated falls during luteolysis.(ABSTRACT TRUNCATED AT 400 WORDS)

Opposite feedback control of renin and aldosterone biosynthesis in the adrenal cortex by angiotensin II AT1-subtype receptors.

The aims of this study were to identify whether tissue renin is regulated by a negative-feedback mechanism produced by locally generated angiotensin (Ang II) in the adrenal cortex and to detect the pathway of Ang II modulation. For this purpose, in 36 12-week old, salt-restricted, nephrectomized Sprague-Dawley rats, we studied the effects of the Ang II AT1-subtype receptor antagonist losartan and of the Ang II AT2-subtype receptor antagonist PD123319 on renin mRNA and activity, aldosterone synthase mRNA, and AT1a-, AT1b-, and AT2-subtype receptor expression in the adrenal cortex. Ten additional rats, kept on a regular diet and then nephrectomized, were also studied. In salt-restricted, nephrectomized rats, losartan administration caused increases of adrenal renin mRNA (P<.05) and activity (P<.05) and a concomitant reduction of aldosterone synthase mRNA (P<.05). In addition, after losartan AT1b, receptor mRNA was reduced (P<.05), AT1a receptor mRNA was unchanged, and AT2 mRNA was increased (P<.05). PD123319 did not significantly modify any of these parameters. In conclusion, in salt-restricted, nephrectomized rats, selective antagonism of AT1-subtype receptors stimulates the expression and the activity of renin in the adrenal cortex. This observation demonstrates that Ang II locally formed in the adrenal cortex exerts a modulatory negative-feedback action on adrenal renin biosynthesis independent of the influence of the circulating renin-Ang system; this action is largely mediated through the AT1b-subtype receptors.