Glucocorticoids with or without fludrocortisone in septic shock: a narrative review from a biochemical and molecular perspective

Two randomised controlled trials have reported a reduction in mortality when adjunctive hydrocortisone is administered in combination with fludrocortisone compared with placebo in septic shock. A third trial did not support this finding when hydrocortisone administered in combination with fludrocortisone was compared with hydrocortisone alone. The underlying mechanisms for this mortality benefit remain poorly understood. We review the clinical implications and potential mechanisms derived from laboratory and clinical data underlying the beneficial role of adjunctive fludrocortisone with hydrocortisone supplementation in septic shock. Factors including distinct biological effects of glucocorticoids and mineralocorticoids, tissue-specific and mineralocorticoid receptor-independent effects of mineralocorticoids, and differences in downstream signalling pathways between mineralocorticoid and glucocorticoid binding at the mineralocorticoid receptor could contribute to this interaction. Furthermore, pharmacokinetic and pharmacodynamic disparities exist between aldosterone and its synthetic counterpart fludrocortisone, potentially influencing their effects. Pending publication of well-designed, randomised controlled trials, a molecular perspective offers valuable insights and guidance to help inform clinical strategies.

Fludrocortisone Induces Aortic Pathologies in Mice

BACKGROUND AND OBJECTIVE

In an experiment designed to explore the mechanisms of fludrocortisone-induced high blood pressure, we serendipitously observed aortic aneurysms in mice infused with fludrocortisone. The purpose of this study was to investigate whether fludrocortisone induces aortic pathologies in both normocholesterolemic and hypercholesterolemic mice.

METHODS AND RESULTS

Male adult C57BL/6J mice were infused with either vehicle (85% polyethylene glycol 400 (PEG-400) and 15% dimethyl sulfoxide (DMSO); n = 5) or fludrocortisone (12 mg/kg/day dissolved in 85% PEG-400 and 15% DMSO; n = 15) for 28 days. Fludrocortisone-infused mice had higher systolic blood pressure, compared to mice infused with vehicle. Fludrocortisone induced aortic pathologies in 4 of 15 mice with 3 having pathologies in the ascending and aortic arch regions and 1 having pathology in both the ascending and descending thoracic aorta. No pathologies were noted in abdominal aortas. Subsequently, we infused either vehicle (n = 5/group) or fludrocortisone (n = 15/group) into male ApoE -/- mice fed a normal laboratory diet or LDL receptor -/- mice fed either normal or Western diet. Fludrocortisone increased systolic blood pressure, irrespective of mouse strain or diet. In ApoE -/- mice infused with fludrocortisone, 2 of 15 mice had ascending aortic pathologies, but no mice had abdominal aortic pathologies. In LDL receptor -/- mice fed normal diet, 5 had ascending/arch pathologies and 1 had pathologies in the ascending, arch, and suprarenal aortic regions. In LDL receptor -/- mice fed Western diet, 2 died of aortic rupture in either the descending thoracic or abdominal region, and 2 of the 13 survived mice had ascending/arch aortic pathologies. Aortic pathologies included hemorrhage, wall thickening or thinning, or dilation. Only ascending aortic diameter in LDLR -/- mice fed Western diet reached statistical significance, compared to their vehicle.

CONCLUSION

Fludrocortisone induces aortic pathologies independent of hypercholesterolemia. As indicated by the findings in mouse studies, people who are taking or have taken fludrocortisone might have an increased risk of aortic pathologies.

Catch-up Growth and Discontinuation of Fludrocortisone Treatment in Aldosterone Synthase Deficiency

BACKGROUND

Aldosterone synthase deficiency (ASD) caused by mutations in the CYP11B2 gene is characterized by isolated mineralocorticoid deficiency. Data are scarce regarding clinical and biochemical outcomes of the disease in the follow-up.

OBJECTIVE

Assessment of the growth and steroid profiles of patients with ASD at the time of diagnosis and after discontinuation of treatment.

DESIGN AND METHOD

Children with clinical diagnosis of ASD were included in a multicenter study. Growth and treatment characteristics were recorded. Plasma adrenal steroids were measured using liquid chromatography-mass spectrometry. Genetic diagnosis was confirmed by CYP11B2 gene sequencing and in silico analyses.

RESULTS

Sixteen patients from 12 families were included (8 females; median age at presentation: 3.1 months, range: 0.4 to 8.1). The most common symptom was poor weight gain (56.3%). Median age of onset of fludrocortisone treatment was 3.6 months (range: 0.9 to 8.3). Catch-up growth was achieved at median 2 months (range: 0.5 to 14.5) after treatment. Fludrocortisone could be stopped in 5 patients at a median age of 6.0 years (range: 2.2 to 7.6). Plasma steroid profiles revealed reduced aldosterone synthase activity both at diagnosis and after discontinuation of treatment compared to age-matched controls. We identified 6 novel (p.Y195H, c.1200 + 1G > A, p.F130L, p.E198del, c.1122-18G > A, p.I339_E343del) and 4 previously described CYP11B2 variants. The most common variant (40%) was p.T185I.

CONCLUSIONS

Fludrocortisone treatment is associated with a rapid catch-up growth and control of electrolyte imbalances in ASD. Decreased mineralocorticoid requirement over time can be explained by the development of physiological adaptation mechanisms rather than improved aldosterone synthase activity. As complete biochemical remission cannot be achieved, a long-term surveillance of these patients is required.

Anti-inflammatory and neuroprotective properties of the corticosteroid fludrocortisone in retinal degeneration

The pathogenesis of outer retinal degenerations has been linked to the elevation of cytokines that orchestrate pro-inflammatory responses within the retinal milieu, and which are thought to play a role in diseases such as geographic atrophy (GA), an advanced form of AMD. Here we sought investigate the anti-inflammatory and mechanistic properties of fludrocortisone (FA), as well as triamcinolone acetonide (TA), on Müller cell-mediated cytokine expression in response to inflammatory challenge. In addition, we investigated the neuroprotective efficacy of FA and TA in a photo-oxidative damage (PD), a model of outer retinal degeneration. Expression of CCL2, IL-6, and IL-8 with respect to FA and TA were assessed in Müller cells in vitro, following simulation with IL-1β or TNF-α. The dependency of this effect on mineralocorticoid and glucocorticoid signaling was also interrogated for both TA and TA via co-incubation with steroid receptor antagonists. For the PD model, C57BL/6 mice were intravitreally injected with FA or TA, and changes in retinal pathology were assessed via electroretinogram (ERG) and optical coherence tomography (OCT). FA and TA were found to dramatically reduce the expression of CCL2, IL-6, and IL-8 in Müller glia in vitro after inflammatory challenge with IL-1β or TNF-α (P < 0.05). Though FA acts as both a mineralocorticoid and glucocorticoid receptor agonist, co-incubation with selective steroid antagonists revealed that the suppressive effect of FA on CCL2, IL-6, and IL-8 expression is mediated by glucocorticoid signaling (P < 0.05). In PD, intravitreal FA was found to ameliorate outer-retinal atrophy as measured by ERG and OCT (P < 0.05), while TA had no significant effect (P > 0.05). Our data indicate potent anti-inflammatory and mechanistic properties of corticosteroids, specifically FA, in suppressing inflammation and neurodegeneration degeneration associated with outer retinal atrophy. Taken together, our findings indicate that corticosteroids such as FA may have value as a potential therapeutic for outer retinal degenerations where such pro-inflammatory factors are implicated, including AMD.

Influence of glucocorticoid and mineralocorticoid receptor stimulation on task switching

The influence of stress on executive functions has been demonstrated in numerous studies and is potentially mediated by the stress-induced cortisol release. Yet, the impact of cortisol on cognitive flexibility and task switching in particular remains equivocal. In this study, we investigated the influence of pharmacological glucocorticoid receptor (GR) and mineralocorticoid receptor (MR) stimulation, two corticosteroid receptor types known to be responsible for cortisol effects on the brain. We conducted two experiments, each with 80 healthy participants (40 women and 40 men), and tested the effect of the unspecific MR/GR agonist hydrocortisone (Experiment I) and the more specific MR agonist fludrocortisone (Experiment II) on switch costs and task rule congruency in a bivalent, cued task switching paradigm. The results did not confirm our hypotheses; we found no significant effects of our manipulations on task switching capacity, although general switching and congruency effects were observed. We discuss the absence of MR/GR-mediated effects and propose alternative mechanisms that could explain stress induced effects on task switching.

Hypertension in children with congenital adrenal hyperplasia

OBJECTIVES

Estimates of high blood pressure (BP) incidence in children with congenital adrenal hyperplasia (CAH) vary widely; risk factors are poorly understood. We estimated incidence of hypertension by CAH subtype and sex, and assessed its association with body mass index, hydrocortisone and fludrocortisone.

DESIGN

Longitudinal.

PATIENTS

Chart review of 180 paediatric CAH patients (120 salt wasting; 60 simple virilizing; 93 females) seen from 1970 to 2013.

MEASUREMENTS

High BP was diagnosed by diastolic or systolic blood pressure measurement ≥95th percentile for age, sex and height; hypertension was diagnosed with high BP on at least three clinic visits.

RESULTS

Children with classic CAH who received fludrocortisone had a significantly higher rate of hypertension (55% vs 31%) than those who did not. Hypertension incidence was higher in salt-wasting CAH (58%) than in simple-virilizing CAH (35%). Hypertension first occurred before age 5 years in 91% of salt-wasting males and 50% of cases in salt-wasting females; most simple-virilizing cases occurred during ages 10-18 years. Rates of hypertension were higher in children who had three or more measurements with 17-OHP < 400 ng/dl (12·12 nmol/l), and this difference was significant in salt-wasting males. Children on fludrocortisone who had three or more readings of 17-OHP < 400 ng/dl (12·12 nmol/l) had a significantly higher rate of hypertension than those who did not. Hydrocortisone dose was not associated with hypertension.

CONCLUSION

Children with CAH are at higher risk for hypertension than the general paediatric population, and incidence differs by sex and CAH subtype. Hypertension was higher in children on fludrocortisone and who were oversuppressed.

The acute effect of a mineralocorticoid receptor agonist on corticotrope secretion in Addison's disease

PURPOSE

Mineralocorticoid receptors (MR) in the hippocampus display an important role in the control of hypothalamic-pituitary-adrenal (HPA) axis, mediating the ''proactive'' feedback of glucocorticoids (GC). Fludrocortisone (FC), a potent MR agonist, has been shown to decrease HPA activity through a hippocampal mechanism. Since it has been demonstrated that FC shows a significant inhibition of the HPA axis response to hCRH stimulus in normal subjects, also at doses usually administered as replacement therapy in patients with Addison's disease, an FC effect at MRs in human pituitary or a GR-pituitary agonism stronger than believed until now has been postulated.

METHODS

Ten patients affected by autoimmune Addison's disease received: (1) placebo p.o. + placebo i.v., (2) hydrocortisone (H) 10 mg p.o. + placebo i.v., (3) FC 0.1 mg p.o. + placebo i.v., (4) FC 0.1 mg and H 10 mg p.o. + placebo i.v. to verify a possible GR FC-mediated effect that might display a repercussion on the GC-replacement therapy.

RESULTS

H reduced ACTH (p < 0.01) and increased cortisol levels (p < 0.01) with respect to the placebo session, while FC did not affect either ACTH or cortisol levels compared to placebo, and higher ACTH and lower cortisol levels (p < 0.03 and p < 0.01) were observed compared with the H session; furthermore the co-administration of FC + H showed ACTH and cortisol profiles similar to that observed during H alone.

CONCLUSIONS

Our study showed a lack of FC effect on corticotrope secretion in Addison's disease, thus making unlikely the hypothesis of its GR pituitary agonism and the risk of glucocorticoid excess in primary adrenal insufficiency.

Selective screening for distal renal tubular acidosis in recurrent kidney stone formers: initial experience and comparison of the simultaneous furosemide and fludrocortisone test with the short ammonium chloride test

BACKGROUND

Distal renal tubular acidosis (dRTA) is associated with renal stone disease, and it often needs to be considered and excluded in some recurrent calcium kidney stone formers (KSFs). However, a diagnosis of dRTA, especially when 'incomplete', can be missed and needs to be confirmed by a urinary acidification (UA) test. The gold standard reference test is still the short ammonium chloride (NH₄Cl) test, but it is limited by gastrointestinal side effects and occasionally failure to ingest sufficient NH₄Cl. For this reason, the furosemide plus fludrocortisone (F+F) test has been proposed as an easier and better-tolerated screening test. The aim of the present study was to assess the usefulness of the F+F test as a clinical screening tool for dRTA in a renal stone clinic.

METHODS

We studied 124 patients retrospectively in whom incomplete dRTA was suspected: 71 had kidney stones only, 9 had nephrocalcinosis only and 44 had both. A total of 158 UA tests were performed: 124 F+F and 34 NH₄Cl; both tests were completed in 34 patients.

RESULTS

The mean age was 45.4 ± 15 years, and 49% of patients were male. The prevalence of complete and incomplete dRTAs was 7 and 13.7%, respectively. Of the 34 patients tested using both tests, 17 (50%) were abnormal and 4 (12%) were normal. Thirteen (39%) patients were abnormal by F+F, but normal by NH₄Cl [sensitivity 100% (95% CI 80-100), specificity 24% (95% CI 7-50), positive predictive value 57% (95% CI 37-75), negative predictive value 100% (95% CI 40-100)].

CONCLUSIONS

The F+F test is characterized by an excellent sensitivity and negative predictive value, and the diagnosis of incomplete dRTA can be excluded reliably in a patient who acidifies their urine normally with this test. However, its lack of specificity is a drawback, and if there is any doubt, an abnormal F+F test may need to be confirmed by a follow-up NH₄Cl test. Ideally, a prospective blinded study in unselected KSFs is needed to accurately assess the reliability of the F+F test in diagnosing, rather than excluding, dRTA.

Overnight suppression of HPA axis after mineraolocorticoid receptor stimulation: A sleep endocrine study

Nocturnal hyperactivity of hypothalamic-pituitary-adrenal axis (HPA) indicates decreased feedback inhibition with stress-related conditions such as major depression and sleep disorders. To characterize the role of mineralocorticoid (MR) in regulation of HPA axis activity during nocturnal sleep and involvement in sleep architecture, we investigated sleep endocrine effects of the MR agonist fludrocortisone in healthy men after pretreatment with metyrapone to minimize the impact of endogenous cortisol. Subjects (n=8) were treated on three occasions in a single-blinded design in random order with a) metyrapone, b) fludrocortisone after metyrapone, and c) placebo. Polysomnography was recorded and blood samples were drawn for determination of adrenocorticotropic hormone (ACTH) and cortisol during the entire night. After metyrapone administration ACTH was significantly enhanced, while overall nocturnal cortisol secretion remained largely unchanged. Whereas administration of fludrocortisone induced a significant inhibitory effect on basal ACTH and cortisol secretion, no considerable effects on sleep pattern were detectable. While the involvement of MR in sleep regulation needs further study, endocrine findings underline the role of MR in tonic regulation of HPA axis during nocturnal sleep and demonstrate the ability of fludrocortisone to further suppress HPA axis activity overnight. Additional studies would be required to evaluate endocrine and clinical fludrocortisone effects in depressive patients showing HPA hyperactivity.

Does fludrocortisone influence autobiographical memory retrieval? A study in patients with major depression, patients with borderline personality disorder and healthy controls

There is evidence that stimulation of mineralocorticoid receptors (MR) enhances memory in healthy subjects and in patients with major depression (MDD). In contrast, in patients with borderline personality disorder (BPD), this effect seems to be task dependent. The aim of this study was to investigate the effect of MR stimulation on autobiographical memory retrieval in healthy individuals, patients with MDD, and patients with BPD. We conducted a placebo-controlled study in an intra-individual cross-over design. Twenty-four patients with MDD, 37 patients with BPD, and 67 healthy participants completed an autobiographical memory test after receiving 0.4 mg fludrocortisone, a mineralocorticoid receptor preferring agonist, or placebo in a randomized order. Healthy subjects, patients with MDD, and patients with BPD did not differ in their autobiographical memory retrieval. Furthermore, the administration of fludrocortisone had no effect on autobiographical memory. In conclusion, the stimulation of MR does not influence autobiographical memory retrieval in healthy subjects, patients with MDD, and patients with BPD. Our results do not support a role of MR in autobiographical memory.

The acute effect of fludrocortisone on basal and hCRH-stimulated hypothalamic--pituitary--adrenal (HPA) axis in humans

Mineralocorticoid receptors (MR) in the hippocampus display an important role in the control of hypothalamic-pituitary-adrenal (HPA)-axis, mediating the "proactive"-feedback of glucocorticoids. Fludrocortisone (FC), a potent MR agonist, has been shown to decrease HPA activity through a mechanism placed at hippocampal level. In order to clarify the effects of MR agonism on HPA function in humans, we studied the effects of FC, in a dose-related manner, on both basal and CRH-stimulated HPA axis during the quiescent phase. 8 young women were studied. ACTH, cortisol and aldosterone levels were evaluated every 15', from 1600 to 2000 hours, in randomized sessions: (1) placebo p.o. + placebo i.v., (2) 0.3 mg FC p.o. + placebo, (3) 0.1 mg FC. + placebo, (4) 0.075 mg FC + placebo, (5) 0.05 mg FC + placebo, (6) placebo + hCRH (2.0 μg/kg iv-bolus), (7) 0.3 mg FC + hCRH, (8) 0.1 mg FC + hCRH, (9) 0.075 mg FC + hCRH, (10) 0.05 mg FC + hCRH. FC induced a dose-related trend toward a further decrease of the ACTH and cortisol levels, while it showed a significant and dose-dependent inhibition of the hormonal response to hCRH (p < 0.05 for the doses of 0.3, 0.1 and 0.075 mg). Conversely, 0.05 mg FC did not modify the CRH-stimulatory effect on both ACTH and cortisol secretion. Aldosterone levels were not modified by FC administration. Fludrocortisone inhibits corticotrope and adrenal response to hCRH in humans, in a dose-dependent manner. The 0.075 mg FC seems the lowest active while 0.05 mg the first neutral dose on HPA activity. These data suggest a possible hypophysial MR-mediated inhibiting effect of FC, although its pituitary glucocorticoid-mediated effect cannot be excluded. The interplay between fludrocortisone and hypophysial glucocorticoid receptors needs to be clarified in order to define better the clinical consequences of the hormonal replacement therapy of patients with primary adrenal insufficiency.

Age-related cochlear cytokine gene expression in the BALB/cJ mouse with systemic versus intratympanic dosing of steroid drugs

CONCLUSION

Age-related differences in the expression of inflammatory cytokines in the inner ear may contribute to the development of age-related hearing loss (ARHL).

OBJECTIVES

ARHL is characterized by tissue remodeling, ischemia, ion homeostasis, and inflammation. Steroid therapy is an otoprotective strategy that likely acts by reducing inflammation. We examined age-related changes in cytokine gene expression in the cochlea of the BALB/cJ mouse model of premature ARHL after systemic or intratympanic steroid delivery.

METHODS

'Young' (2.5-3 months) and 'Old' (5-9 months) mice were treated with dexamethasone or fludrocortisone administered either orally or intratympanically. Cytokine gene expression in cochlear RNA was analyzed using prefabricated cDNA arrays. Old groups were compared to Young groups to identify age-related changes.

RESULTS

Down-regulation of a cytokine associated with bone remodeling (SPP1) was observed in the untreated Old group. Numerous genes were up- or down-regulated by more than twofold by steroid treatment, including proinflammatory interleukins (IL-16) and anti-inflammatory cytokines.

The acute effects of a mineralocorticoid receptor (MR) agonist on nocturnal hypothalamic-adrenal-pituitary (HPA) axis activity in healthy controls

INTRODUCTION

Both glucocorticoid and mineralocorticoid receptors (GRs and MRs) help modulate cortisol feedback on the hypothalamic-adrenal-pituitary (HPA) axis. In brain, MRs inhibit the HPA axis and are thought to be fully occupied. Thus, prior studies of the effects of an MR agonist on HPA axis activity have first used metyrapone to inhibit cortisol production and to consequently deplete the receptors. Herein, we propose that an MR agonist may inhibit the HPA axis without first "unloading" receptors of endogenous cortisol.

METHODS

Healthy subjects were admitted to the General Clinical Research Center. Blood was sampled for cortisol and adrenocorticotropic hormone (ACTH) from 16:00 to 24:00 h, when greatest MR activity is expected, on two consecutive nights. The first night established a baseline and the second night established response. On the second afternoon, all subjects were given 0.5mg fludrocortisone. Mean cortisol and ACTH were computed from 16:00 to 24:00 h.

RESULTS

Fludrocortisone acutely decreased mean cortisol (p=0.003; effect size (ES) 1.65) and mean ACTH (p=0.000, ES 4.46). Additionally, post hoc analysis showed that fludrocortisone tended to decrease the cortisol/ACTH ratio (p=0.0686, ES 0.92) across the same time period.

CONCLUSIONS

Fludrocortisone significantly inhibits nocturnal HPA axis activity without first depleting MR receptors with metyrapone. This suggests that brain MRs are not fully occupied by endogenous cortisol and can be further activated by an agonist. The decrease in cortisol/ACTH ratio suggests a possible role on adrenal sensitivity as well. The ability to lower nocturnal HPA axis activity has interesting implications in disorders of HPA axis excess, such as insomnia, depression and healthy aging.

Influence of Acute and Chronic Mineralocorticoid Excess on Endothelial Function in Healthy Men

Aldosterone has rapid nongenomic effects in the human vasculature. However, data are not uniform and little is known about chronic effects of aldosterone. Therefore, we investigated acute and chronic effects of elevated aldosterone levels on endothelial function in the forearm vasculature of healthy men. In a first crossover study, the effects of arterial aldosterone infusion in ascending doses (3.3 to 55 pmol/min per 1000 mL forearm volume) on forearm blood flow were investigated in 8 healthy men (26+/-2 years). In a second study, endothelium-dependent (acetylcholine; 0.08, 0.275, and 2.75 micromol/min per 1000 mL) and endothelium-independent (sodium nitroprusside 0.02 micromol/min per 1000 mL) vasodilation and basal nitric oxide formation (forearm blood flow response to blockade by N(G)-monomethyl-l-arginine 8 micromol/min per 1000 mL) were tested in 10 healthy men (age 30+/-5 years) at baseline, during infusion of 55 pmol/1000 mL per min aldosterone (acute effects), and after 0.3 mg/d oral fludrocortisone for 2 weeks (chronic effects) on separate days. Forearm blood flow was assessed by venous occlusion plethysmography. No change in forearm blood flow was seen with aldosterone infusion alone. Acute coinfusion of aldosterone increased vasodilation to sodium nitroprusside by 93% (P<0.01) and to acetylcholine by 60% (P=0.14). Response to N(G)-monomethyl-l-arginine did not change. After 2 weeks of oral fludrocortisone, response to acetylcholine was enhanced by 72% compared with baseline (P=0.03). Additionally, response to N(G)-monomethyl-l-arginine was enhanced by 80% compared with baseline (P=0.05). Aldosterone acutely enhances vasodilation to exogenous nitric oxide whereas mineralocorticoid excess for 2 weeks enhances basal nitric oxide bioactivity and improves endothelium dependent, nitric oxide-mediated vasodilation in the forearm vasculature of healthy men.

Primary aldosteronism: diagnostic and treatment strategies

Primary aldosteronism is caused by bilateral idiopathic hyperplasia in approximately two-thirds of cases and aldosterone-producing adenoma in one-third. Most patients with primary aldosteronism are normokalemic. In the clinical setting of normokalemic hypertension, patients who have resistant hypertension and hypertensive patients with a family history atypical for polygenic hypertension should be tested for primary aldosteronism. The ratio of plasma aldosterone concentration to plasma renin activity has been generally accepted as a first-line case-finding test. If a patient has an increased ratio, autonomous aldosterone production must be confirmed with an aldosterone suppression test. Once primary aldosteronism is confirmed, the subtype needs to be determined to guide treatment. The initial test in subtype evaluation is CT imaging of the adrenal glands. If surgical treatment is considered, adrenal vein sampling is the most accurate method for distinguishing between unilateral and bilateral adrenal aldosterone production. Optimal treatment for aldosterone-producing adenoma or unilateral hyperplasia is unilateral laparoscopic adrenalectomy. The idiopathic bilateral hyperplasia and glucocorticoid-remediable aldosteronism subtypes should be treated pharmacologically. All patients treated pharmacologically should receive a mineralocorticoid receptor antagonist, a drug type that has been shown to block the toxic effects of aldosterone on nonepithelial tissues.

Urinary Prostasin

Prostasin is a serine peptidase hypothesized to regulate epithelial sodium channel (ENaC) activity in animals or on in vitro cultured cells. We investigated whether urinary prostasin may be a candidate marker of ENaC activation in humans. We studied 10 healthy volunteers and 8 hypertensive patients with raised aldosterone-to-renin ratio before and after spironolactone or saline/Florinef suppression test, respectively. Four healthy subjects were also studied before and after saline. Urinary prostasin was evaluated by SDS-PAGE, 2D maps, and Western blotting. Every sample of normotensive individuals was compared with the corresponding sample of urine collected after spironolactone or saline; every sample of hypertensive patients was compared with the corresponding sample of urine collected after saline or Florinef. Prostasin was detectable in all subjects regardless of gender, dietary sodium intake, and spironolactone treatment. Spironolactone (100 mg) increased urinary Na+/K+ ratio and decreased urinary prostasin in normotensives in whom the renin/aldosterone axis was activated by a low Na+ intake, but it was ineffective in individuals with high Na+ intake. Saline infusion also reduced prostasin in normotensive subjects. In contrast, prostasin paradoxically increased in urine of patients affected by primary aldosteronism after volume expansion. By 2D immunoblotting, several protein isoforms were observed, some of them being overexpressed after inhibition tests in patients with primary aldosteronism. In addition to a "basal" aliquot of prostasin, constitutively released in human urine regardless of sodium balance and aldosterone activation, there exists a second "aldosterone-responsive" aliquot modulated by Na+ intake and potentially suitable as candidate marker of ENaC activation.

Impact of availability of oral hydrocortisone on growth of children with CAH

OBJECTIVES

1. To compare growth parameters of patients with Congenital Adrenal Hyperplasia (CAH) managed on Prednisolone (PR) before and on Hydrocortisone (HC) after its availability in India. 2. To compare growth parameters of patients with CAH who have been on treatment with HC since diagnosis with patients managed on PR.

METHODS

Growth parameters of twelve children (8 m, 4 f) with congenital adrenal hyperplasia were retrospectively studied while on treatment with prednisolone (PR) earlier and then hydrocortisone (HC) after it became freely available in India.

RESULTS

Patients treated with PR had height Z score of -0.42, weight Z score of - 0.45, and height velocity Z score of -2.06. On HC these scores were -0.27, +0.16 and + 2.27. Patients treated with HC from the begining had a height Z Score of + 0.08, weight Z score of +0.22, and height velocity Z score of +0.68.

CONCLUSION

Hydrocortisone has a less growth effect than prednisolone and patients treated with HC from the beginning showed near normal growth.

Mineralocorticoid and glucocorticoid receptors and their differential effects on memory performance in people with Addison's disease

The effects of corticosteroids on memory performance have been the subject of some controversy. Whilst many studies have shown that high levels of corticosteroids can impair memory performance, others have shown they can facilitate it. One explanation for these discrepant effects arises from the differential activation of the two types of corticosteroid receptor--the mineralocorticoid receptor (MRs) and the glucocorticoid receptor (GRs), and the function each subserves during memory formation. Studies in rats and chickens suggest that activation of the MRs is essential during sensory storage (i.e. encoding), whereas normal levels of activation of the GRs (in addition to the already activated MRs) is essential during memory consolidation and retrieval. By using a repeated measures design with nine people with Addison's disease (mean age, 37.9 years), the effects following activation of the MRs only, GRs only, and a combination of MRs/GRs, on working memory and the episodic and semantic components of declarative memory were investigated. MRs and GRs were activated using either MR specific (9 alpha fluorohydrocortisone) or GR specific (dexamethasone) exogenous steroids, respectively. The results showed that participants performed better in the Digits Backward task when both receptors were activated compared to when GRs only were activated (P<0.01). They also performed better in recall in the Hopkins Verbal Learning Test when both receptors were activated compared to when MRs only were activated (P<0.05) and GRs only were activated (P<0.01). Whilst significant effects were not consistent across memory tasks, these results lend further support to the view that balanced activation of MRs and GRs is necessary for optimal memory function in humans.

Pregnancy after liver transplantation with tacrolimus immunosuppression: a single center's experience update at 13 years

BACKGROUND

Chronic liver disease often leads to amenorrhea in women of childbearing age. There are several reports of successful pregnancy after liver transplantation (LTx) with cyclosporine A immunosuppression. Tacrolimus has been increasingly used in solid-organ transplantation, and the effect of the drug on pregnancy is still of interest to clinicians. This study updates our single-center experience.

METHODS

All pregnancies after LTx with tacrolimus immunosuppression were followed prospectively. Patients' clinical courses during pregnancy and labor along with gestational period and birth weight were catalogued. Changes in liver function, renal function, and immunosuppression also were recorded. The birth weight percentile was calculated on the basis of the gestational period using a standard chart.

RESULTS

Thirty-seven mothers delivered 49 babies. Three mothers delivered three times, and six mothers delivered two times. Thirty-six mothers (97%) survived the pregnancy, and 36 allografts (97%) survived. The one death and graft loss was in a patient who demonstrated infra-aortic arterial graft, which clotted by the gravid uterus during labor. The patient developed a gangrenous liver and died before she could undergo retransplantation. The mean gestational period was 36.4+/-3.2 weeks, excluding two premature deliveries at 23 and 24 weeks gestation. Twenty-two babies (46.9%) were delivered by cesarean section, and the other babies were delivered vaginally. In addition to the two premature babies, one baby, who was born to a mother with Alagille syndrome, died from congenital birth defects. The rest of the newborns survived. The mean birth weight was 2,797+/-775 g, with 38 babies (78%) weighing more than 2,000 g. The mean birth weight percentile to gestational period was 54+/-23. Four babies (8.5%) had a birth weight percentile of less than 25, and 28 babies (59.6%) had a birth weight percentile greater than 50. Twelve patients demonstrated an increase in hepatic enzymes without jaundice during the pregnancy. All of them responded to augmentation of immunosuppression.

CONCLUSION

The present report reconfirms the safety of tacrolimus during pregnancy after LTx. Preterm delivery and low birth weight seem to be a persistent problem in all solid-organ transplantation under any form of immunosuppression. However, toxemia of pregnancy and new onset of hypertension seem to be have a low occurrence with the use of tacrolimus.

Mineralocorticoid Receptor-Mediated Inhibition of the Hypothalamic-Pituitary-Adrenal Axis in Aged Humans

In aged humans, diminished mineralocorticoid receptor (MR)-mediated feedback in the brain could contribute to impaired feedback regulation of the hypothalamic-pituitary-adrenal (HPA) axis, but no study specifically compared young and old individuals with regard to MR function. We examined 10 healthy young (mean age +/- SD [standard deviation] 26.1 +/- 2.9 years) and 10 elderly men (68.3 +/- 4.7 years) at the nadir of cortisol levels (2:00 pm-9:00 pm) when HPA activity is mainly controlled by the MR. After pretreatment with 3 g metyrapone to minimize the impact of basal endogenous cortisol secretion, participants received orally, in randomized order on two separate occasions, either 0.5 mg of the MR agonist fludrocortisone or placebo. Fludrocortisone significantly decreased maximum adrenocorticotropic hormone (ACTH) and cortisol concentrations in both groups. ACTH and cortisol values after fludrocortisone were significantly higher in older men compared with young men. Our results implicate that a decrease in MR-mediated negative feedback contributes to the diminished feedback activity in older humans.

Sexual dimorphism in the synchrony of joint growth hormone and cortisol dynamics in children with classic 21-hydroxylase deficiency

In humans, growth hormone (GH) and cortisol are secreted in a pulsatile fashion and a mutual bidirectional interaction between the GH/insulin-like growth factor (IGF)-I axis and hypothalamic-pituitary-adrenal (HPA) axis has been established. Classic congenital adrenal hyperplasia (CAH) is characterized by a defect in the synthesis of glucocorticoids and often mineralocorticoids, and adrenal hyperandrogenism. In view of the sexually dimorphic pattern in GH secretion, we investigated the GH-cortisol bihormonal secretory dynamics in male and female children with classic CAH. Thirty-eight children with classic 21-hydroxylase deficiency (M: 13, F: 25; age range: 6.1-18.8 yr) were studied prospectively. Serum GH and cortisol concentrations were determined at 20 min intervals for 24 hours. The irregularity of GH and cortisol pattern was assessed using approximate entropy (ApEn), a scale- and model-independent statistic. The synchrony of joint GH-cortisol dynamics was quantified using the cross-ApEn statistic. Cross-correlation analysis of GH and cortisol concentrations was computed at various time lags covering the 24-h period. There was no gender difference in mean 24-hour serum GH (males vs females: 5.25 +/- 4.72 vs 4.44 +/- 2.64 mIU/l) or cortisol (156.2 +/- 44.6 vs 172.0 +/- 58.5 nmol/l) concentrations. For GH, ApEn values were significantly higher in females (0.66 +/- 0.14) than in males (0.53 +/- 0.16) (p = 0.009). No difference in cortisol ApEn values was noted between sexes (0.53 +/- 0.21 vs 0.54 +/- 0.12). Cross-ApEn values of paired GH-cortisol, with cortisol leading GH, were significantly higher in females (0.94 +/- 0.14) than in males (0.83 +/- 0.20) (p = 0.03). These findings suggest that females with classic 21-hydroxylase deficiency have a more irregular pattern of GH secretion and a more asynchronous joint GH and cortisol dynamics than their male counterparts.

The mineralocorticoid receptor agonist, fludrocortisone, inhibits pituitary-adrenal activity in humans after pre-treatment with metyrapone

Whereas animal studies have shown a clear inhibitory effect of hippocampal mineralocorticoid receptors (MR) on hypothalamic-pituitary-adrenal (HPA) axis activity, investigations in humans revealed equivocal results. To further clarify the influence of MR in HPA activity we studied 10 healthy men during the circadian nadir of HPA activity (14:00 to 21:00) after pre-treatment with 3 g metyrapone to minimize the impact of basal endogenous cortisol secretion. On three separate occasions, in a placebo-controlled design, subjects received in a randomized order either 0.5 mg fludrocortisone p.o. or 0.2 mg aldosterone i.v. or placebo. Fludrocortisone exerted a significant inhibition of ACTH, cortisol and 11-desoxycortisol (p < 0.05), whereas no such effect was observed after aldosterone or placebo. These preliminary data suggest that MR are involved in the inhibition of the HPA axis during the circadian nadir of glucocorticoid concentrations in humans.

Diminished renal kallikrein responses to mineralocorticoid stimulation in African Americans: determinants of an intermediate phenotype for hypertension

BACKGROUND

Hypertension is a complex trait with an ill-defined genetic predisposition, in which renal mechanisms seem to be involved even at the early stages. Renal kallikrein excretion is diminished in patients with hypertension, and perhaps even in the early, prehypertensive phases of the syndrome. African Americans, a group at increased risk of developing hypertension, have especially diminished kallikrein expression, coupled with decreased renal excretion of K(+), a known stimulant of kallikrein expression, suggesting an environmental mechanism for their kallikrein deficit. We, therefore, tested whether short-term indirect (K(+)) or direct (fludrocortisone) stimulation of mineralocorticoid activity might be capable of restoring kallikrein excretion in African Americans.

METHODS

Nineteen healthy normotensive young men (n = 10 white, n = 9 African Americans) were treated with the following sequence of four oral medications, each for 1 week: placebo, KCl (120 mEq/day), placebo, and the mineralocorticoid fludrocortisone (0.4 mg/day). At each stage, we measured vital signs, excretion of kallikrein, aldosterone and electrolytes, and serum renin. Results were evaluated by two-way, repeated measures ANOVA.

RESULTS

African Americans had diminished urinary excretion of not only kallikrein (P =.007), but also K(+) (P <.001) and aldosterone (P =.015). Kallikrein responses to mineralocorticoid stimulation were substantially blunted in African Americans, whether achieved indirectly (by supplemental K(+); P =.019) or directly (by the exogenous mineralocorticoid fludrocortisone; P =.027), despite achievement of substantial increments in K(+) excretion after KCl (P =.002), and multiple other mineralocorticoid effects after fludrocortisone (P =.005). The kallikrein increment after KCl was best predicted by renin activity (P =.001) rather than ethnicity. Potassium chloride did not lower blood pressure (BP) in either group (P >.4).

CONCLUSIONS

Restoration of K(+) and aldosterone secretion to levels found in whites does not normalize kallikrein excretion or lower BP in African Americans, at least in the short term. Nor does exogenous mineralocorticoid stimulation fully restore kallikrein expression in African Americans. Therefore, the diminution of kallikrein biosynthesis in African Americans seems to involve mechanisms at or distal to the aldosterone receptor, and perhaps at the level of the kallikrein gene itself.

Angiotensin II feedback is a regulator of renocortical renin, COX-2, and nNOS expression

Salt restriction leads to parallel increases of renin, cyclooxygenase-2 (COX-2), and neuronal nitric oxide synthase (nNOS) gene expression in the juxtaglomerular apparatus of rat kidneys. Because the upregulation of these genes is strongly enhanced if salt restriction is combined with inhibition of the renin-angiotensin-aldosterone system, our study aimed to find out whether the juxtaglomerular expressions of renin, COX-2, and nNOS are subject to a common direct negative feedback control by ANG II. For this purpose, male Sprague-Dawley rats were fed a low-salt diet (0.02% wt/wt) with or without additional treatment with the ANG I-converting enzyme (ACE) inhibitor ramipril (10 mg x kg body wt(-1) x day(-1)) for 1 wk, and renocortical renin, COX-2, and nNOS mRNAs were assayed. To narrow down possible indirect effects of the ACE inhibitor that may result from insufficient aldosterone production, the animals received mineralocorticoid substitution with fludrocortisone (6 mg. kg body wt(-1) x day(-1)). Thus mineralocorticoid substitution prevented the fall of systolic blood pressure and of glomerular filtration induced by ramipril in rats on low-salt diet. Although fludrocortisone had no effect on basal renin, COX-2, and nNOS mRNA, it clearly attenuated the threefold increases of both renin and COX-2 mRNA in response to low-salt diet. In rats on low-salt diet, ramipril further increased renin mRNA ninefold, COX-2 mRNA fourfold, and nNOS 2.5-fold in the absence of fludrocortisone. In the presence of fludrocortisone, ramipril increased renin mRNA 10-fold, COX-2 mRNA 2.5-fold, and nNOS mRNA 2.5-fold. These data indicate that mineralocorticoid substitution lowers the overall expression of juxtaglomerular renin and COX-2 during low-salt intake and attenuates a further rise of COX-2 expression by ACE inhibition, but it does not change the stimulatory effect of ACE inhibition on renin and nNOS expression. We conclude that the expression of renin, COX-2, and nNOS in the juxtaglomerular apparatus during low-salt diet is markedly limited by a direct feedback inhibition through ANG II.

A glucocorticoid-responsive mutant androgen receptor exhibits unique ligand specificity: therapeutic implications for androgen-independent prostate cancer

The cortisol/cortisone-responsive AR (AR(ccr)) has two mutations (L701H and T877A) that were found in the MDA PCa human prostate cancer cell lines established from a castrated patient whose metastatic tumor exhibited androgen-independent growth. Cortisol and cortisone bind to the AR(ccr) with high affinity. In the present study, we characterized the structural determinants for ligand binding to the AR(ccr). Our data revealed that many of the C17, C19, and C21 circulating steroids, at concentrations that are found in vivo, functioned as effective activators of the AR(ccr) but had little or no activity via the wild-type AR or GRalpha. Among the synthetic glucocorticoids tested, dexamethasone activated both GRalpha and AR(ccr), whereas triamcinolone was selective for GRalpha. In MDA PCa 2b cells, growth and prostate-specific antigen production were stimulated by potent AR(ccr) agonists such as cortisol or 9alpha-fluorocortisol but not by triamcinolone (which did not bind to or activate the AR(ccr)). Of the potential antagonists tested, bicalutamide (casodex) and GR antagonist RU38486 showed inhibitory activity. We postulate that corticosteroids provide a growth advantage to prostate cancer cells harboring the promiscuous AR(ccr) in androgen-ablated patients and contribute to their transition to androgen-independence. We predict that triamcinolone, a commonly prescribed glucocorticoid, would be a successful therapeutic agent for men with this form of cancer, perhaps in conjunction with the antagonist casodex. We hypothesize that triamcinolone administration would inhibit the hypothalamic-pituitary-adrenal axis, thus suppressing endogenous corticosteroids, which stimulate tumor growth. Triamcinolone, by itself, would not activate the AR(ccr) or promote tumor growth but would provide glucocorticoid activity essential for survival.

Structural basis for the glucocorticoid response in a mutant human androgen receptor (AR(ccr)) derived from an androgen-independent prostate cancer

The crystal structure of a mutant androgen receptor (AR) ligand-binding domain (LBD) in complex with the agonist 9alpha-fluorocortisol has been determined at 1.95 A resolution. This mutant AR contains two mutations (L701H and T877A) and was previously reported as a high-affinity cortisol/cortisone responsive AR (AR(ccr)) isolated from the androgen-independent human prostate cancer cell lines MDA PCa 2a and 2b (Zhao et al. Nature Med. 2000, 6, 703-6). The three-dimensional structure of the AR(ccr) LBD complexed with 9alpha-fluorocortisol shows the typical conformation of an agonist-bound nuclear receptor in which helix 12 is precisely positioned as a "lid" for the ligand-binding pocket. Binding of 9alpha-fluorocortisol to the AR(ccr) involves favorable hydrogen bond patterns on the C17 and C21 substituents of the ligand due to the mutations at 701 and 877 in the AR(ccr). Our studies provide the first structural explanation for the glucocorticoid activation of AR(ccr), which is important for the development of new therapeutic treatments for androgen-independent prostate cancer.

Endothelial cell dysfunction in mice after transgenic knockout of type 2, but not type 1, 11beta-hydroxysteroid dehydrogenase

BACKGROUND

11beta-Hydroxysteroid dehydrogenase (11betaHSD) isozymes catalyze the interconversion of active and inactive glucocorticoids, allowing local regulation of corticosteroid receptor activation. Both are present in the vessel wall; here, using mice with selective inactivation of 11betaHSD isozymes, we test the hypothesis that 11betaHSDs influence vascular function.

METHODS AND RESULTS

Thoracic aortas were obtained from weight-matched male wild-type (MF1x129 cross(+/+)), 11betaHSD1(-/-), and 11betaHSD2(-/-) mice. mRNA for both isozymes was detected in wild-type aortas by RT-PCR. 11betaHSD activity in aortic homogenates (48.81+/-4.65% conversion) was reduced in both 11betaHSD1(-/-) (6.36+/-2.47% conversion; P<0.0002) and 11betaHSD2(-/-) (24.71+/-3.69; P=0.002) mice. Functional responses were unaffected in aortic rings isolated from 11betaHSD1(-/-) mice. In contrast, aortas from 11betaHSD2(-/-) mice demonstrated selectively enhanced constriction to norepinephrine (E(max) 4.28+/-0.56 versus 1.72+/-0.47 mN/mm; P=0.004) attributable to impaired endothelium-derived nitric oxide activity. Relaxation responses to endothelium-dependent and -independent vasodilators were also impaired. To control for chronic renal mineralocorticoid excess, MF1 mice were treated with fludrocortisone (16 weeks) but did not reproduce the functional changes observed in 11betaHSD2(-/-) mice.

CONCLUSIONS

Although both 11betaHSD isozymes are present in the vascular wall, reactivation of glucocorticoids by 11betaHSD1 does not influence aortic function. Mice with 11betaHSD2 knockout, however, have endothelial dysfunction causing enhanced norepinephrine-mediated contraction. This appears to be independent of renal sodium retention and may contribute to hypertension in 11betaHSD2 deficiency.

Insulin and mineralocorticoids influence on extrarenal potassium metabolism in chronic hemodialysis patients

Insulin-mineral corticoids effects on extrarenal K+ metabolism in dialysis patients. During the inter-dialytic interval in dialyzed patients, hydrogen and potassium ions are regulated by extrarenal mechanisms. We studied the hormonal and acidotic effects on the extrarenal potassium metabolism, in selected, anuric and stable, hemodialysis patients. Fifteen patients, were grouped according to the mean mid-week pre-dialysis K+ over the past 12 months: > 6.0 mEq/L (G1, n=5), = 5.1-6.0 mEq/L (G2, n=5), < or = 5.0 mEq/L (G3, n=5). After a mid-week hemodialysis session and 12 h fasting, they received 1 g/Kg glucose p.os (A). Insulin, aldosterone, renin, pH, HCO3-, glucose, body weight, blood pressure and heart rate were measured before and 60' after the meal. We recorded the same parameters, except insulin, in 15 patients, similarly grouped, before hemodialysis (T0) and on 3 consecutive off dialysis days (T1-T3); G1 received fluorohydrocortisone (FHC) 0.1 mg-0.3 mg/day, according to body weight and G3 spironolactone (SLT) 200 mg per day. G2 were controls (B). (A) A significant rise in glycemia (81 +/- 23 to 157 +/- 52 mg/dL, P<0.001) and insulin (11.8 +/- 6.2 to 46.8 +/- 19.5 microU/mL, P<0.001), with a drop in K+ (5.1 +/- 0.6 to 4.8 +/- 0.7 mEq/L, P=0.001) and aldosterone (453 +/- 373 to 383 +/- 364 pg/mL, P<0.01), were noted at T60 vs. T0, in all groups. Insulin levels correlated negatively (r=-0.54, P<0.04) to serum K+ at T60, in all patients. (B) No major pH, HCO3 and aldosterone changes were observed in the 3 groups. Despite that, K+ dropped in G1 by FHC (6.7 +/- 0.9 to 5.9 +/- 0.6 mEq/L, P<0.05), rose in G3 by SLT (4.4 +/- 0.4 to 5.4 +/- 0.3 mEq/L, P<0.05) and remained unchanged in controls (5.8 +/- 0.2 to 5.8 +/- 0.6 mEq/L), (T0 vs T3 pre-dialysis values). Glucose significantly lowered K+ by promoting adequate insulin secretion. Drugs affecting aldosterone action significantly influenced potassium metabolism. Acid-base balance was not important in K+ handling in steady state anuric dialysis patients.

Close association of urinary excretion of aquaporin-2 with appropriate and inappropriate arginine vasopressin-dependent antidiuresis in hyponatremia in elderly subjects

The present study was undertaken to determine whether urinary excretion of aquaporin-2 (AQP-2) participates in the involvement of arginine vasopressin (AVP) in hyponatremia less than 130 mmol/L in 33 elderly subjects (> or =65 yr old) during the last 5-yr period. Subjects were separated into euvolemic hyponatremia groups: 13 with hypopituitarism, 8 with syndrome of inappropriate secretion of antidiuretic hormone (SIADH), 8 with mineralocorticoid-responsive hyponatremia of the elderly, and 4 with miscellaneous diseases. Approximately 40% of those with hyponatremia was derived from hypopituitarism, but severe hyponatremia was found in the patients with SIADH and mineralocorticoid-responsive hyponatremia of the elderly. Plasma AVP levels remained relatively high despite hypoosmolality and were tightly linked with exaggerated urinary excretion of AQP-2 and antidiuresis in the 3 groups of patients, except for one miscellaneous one. An acute water load test verified the impairment in water excretion, because the percent excretion of the water load was less than 42% and the minimal urinary osmolality was not sufficiently diluted. Also, plasma AVP and urinary excretion of AQP-2 were not reduced after the water load. The inappropriate secretion of AVP was evident in the patients with SIADH and hypopituitarism, and hydrocortisone replacement normalized urinary excretion of AQP-2 and renal water excretion in those with hypopituitarism. In contrast, the appropriate antidiuresis seemed to compensate loss of body fluid in the patients with mineralocorticoid-responsive hyponatremia of the elderly, who lost circulatory blood volume by 7.3% (mean). Fludrocortisone acetate increased renal sodium handling and body fluid, resulting in the reduction in AVP release and urinary excretion of AQP-2 in mineralocorticoid-responsive hyponatremia of the elderly. These findings indicate that urinary excretion of AQP-2 may be a more sensitive measure of AVP effect on renal collecting duct cells than are plasma AVP levels, and that increased urinary excretion of AQP-2 shows exaggerated AVP-induced antidiuresis in hyponatremic subjects in the elderly. In addition, mineralocorticoid-responsive hyponatremia of the elderly has to be carefully differentiated from SIADH in elderly subjects.

Effects of the mineralocorticoid fludrocortisone on fibrinolytic function in healthy subjects

Recent evidence suggests that the renin-angiotensin-aldosterone system (RAAS) may participate in the regulation of fibrinolytic function. Angiotensin II (Ang II) is the primary candidate to mediate this inter-relationship, since this peptide is capable of stimulating plasminogen activator inhibitor-1 (PAI-1) in vitro and in vivo. It has been suggested that aldosterone may also modulate fibrinolysis, possibly by interacting with Ang II. The present study therefore investigates the effect of short-term treatment with the synthetic mineralocorticoid fludrocortisone (F) on fibrinolytic function. Ten healthy male volunteers, aged 25 to 30 years, on a constant intake of 160-180 mmol Na(+) and 60-80 mmol K(+), were studied on a control day (C1), after two days of oral administration of F (0.1 mg b.d.), and again three days after cessation of F (C2). F was associated with a marked decrease in plasma renin activity (PRA) from 0.91 +/- 0.45 ng ml(-1) h(-1) to 0.34 +/- 0.29 ng ml(-1) h(-1) (p=0.005), which returned to the baseline range at C2 (0.65 +/- 0.45 ng ml(-1) h(-1); p=0.032). The experimental protocol was not associated with significant changes in the activity or antigen concentration of tissue plasminogen activator (t-PA). PAI-1 exhibited a circadian rhythm with highest values at 0800 hours (41.8 +/- 9.1 ng/ml), decreasing by 1230 hours (22.6 +/- 5.9 ng/ml), with a further decrease at 1630 hours (12.3 +/- 3.1 ng/ml). At all three time points, PAI-1 remained unchanged by the mineralocorticoid. Our results therefore do not support a major mineralocorticoid effect on PAI-1. However, our study does not exclude a modulatory role of F, since unchanged PAI-1 could be observed in spite of a marked suppression of the RAAS.

Success of surgery for primary aldosteronism judged by residual autonomous aldosterone production

Since February 1996 we have prospectively assessed residual adrenal autonomy by the fludrocortisone suppression test (FST) in 23 patients 3 months after unilateral adrenalectomy for Conn syndrome and in 45 patients after a longer interval. In regard to blood pressure, 36 (53%) patients were cured of hypertension and the remaining 32 (47%) patients had improved hypertension control at the time of their latest postoperative clinical assessment. In regard to the outcome of surgery, patients who achieved normal suppressibility of aldosterone were regarded as cured, and those who had greater suppressibility after surgery were considered improved. Time since surgery for the whole group averaged 26 months. By these biochemical criteria, 42 patients (62%) were cured by surgery, and the rest improved; 16 (76%) of 21 women were cured, and 26 (55%) of 47 men. The women (mean +/- SD age 47 +/- 11 years) were significantly (p < 0.05) younger than the men (52 +/- 9 years). Preoperative aldosterone levels before and after FST were similar in the cured and improved groups and fell significantly (p < 0.01) in both groups following surgery. After surgical reduction of autonomous aldosterone production, mean plasma renin activity levels increased sixfold in the cured group and threefold in the improved group. Surgical mortality in this group of 68 patients with Conn syndrome was zero.

Effect of mineralocorticoid activity on transtubular potassium gradient, urinary [K]/[Na] ratio, and fractional excretion of potassium

Clinical assessment of potassium derangements may require evaluation of mineralocorticoid status. Several indirect indices of mineralocorticoid activity based on renal electrolyte excretion have been proposed and include the transtubular potassium gradient, urinary [K]/[Na] ratio, and renal fractional excretion of potassium. We studied the impact of high mineralocorticoid activity versus blocked mineralocorticoid activity on these indices in otherwise normal subjects who ingested a defined diet. Eight normal subjects received either fludrocortisone or spironolactone for 4 days. After a washout period of > or = 2 weeks, each subject then received the opposite regimen. Subjects ingested an identical high-potassium diet during both experimental periods. The renal fractional excretion of potassium and transtubular potassium gradient were calculated using standard formulas. Fludrocortisone caused an increase in body weight and no significant reduction in serum potassium concentration, while spironolactone decreased body weight and increased plasma potassium concentration. After 1 or 2 days of treatment with fludrocortisone, the average values for all urinary indices of mineralocorticoid activity were significantly higher than after 1 or 2 days of treatment with spironolactone. However, the differences between these indices in the fludrocortisone and spironolactone test periods diminished by day 3 and were nonexistent by day 4. In conclusion, the transtubular potassium gradient, [K]/[Na] ratio, and renal fractional excretion of potassium reflect acute changes in mineralocorticoid activity. However, these indices do not discriminate between states of high and low mineralocorticoid activity lasting longer than 2 to 3 days.

Ambulatory 24-hour blood pressure recordings in patients with Parkinson's disease with or without fludrocortisone

Orthostatic hypotension is often associated with patients suffering from Parkinson's disease. Only few studies have been published about the ambulatory blood pressure in patients with Parkinson's disease. Fludrocortisone has been used in management of orthostatic hypotension. This study was made to determine the Circadian rhythm of blood pressure in healthy elderly people, in Parkinson's disease patients without orthostatic hypotension and Parkinson's disease patients with fludrocortisone medication for orthostatic hypotension. Ambulatory 24-hour blood pressure recordings were made in 20 elderly Parkinson's disease patients and 21 healthy elderly persons. Eight of the Parkinson's disease patients were on fludrocortisone (Florinef) therapy because of orthostatic hypotension. The mean daytime systolic blood pressure of Parkinson's disease patients without fludrocortisone was 123 mmHg and the mean nighttime systolic blood pressure was 121 mmHg. There was no significant difference between daytime and nighttime systolic blood pressure (Figure 1). Diastolic blood pressure in this group was significantly higher during the day (68 mmHg) than at night (63 mmHg) (Figure 2). The daytime blood pressure of control patients was 135/74 mmHg and at night 127/69 mmHg (Figures 1, 2). The blood pressure of Parkinson's disease patients with fludrocortisone was higher at night (156/83 mmHg) than during the day (134/77 mmHg) (Figures 1, 2). The daytime and nighttime systolic and diastolic blood pressure was significantly lower by non-fludrocortisone Parkinson patients than the blood pressure of fludrocortisone Parkinson patients (Figures 1, 2).

CONCLUSION

The Parkinson's disease patients were non-dippers and with fludrocortisone the blood pressure was higher at night than on day. On day, the blood pressure of the Parkinson's disease patients with fludrocortisone elevated to the level of controls.

Rapid effects of corticosteroids on cytosolic protein kinase C and intracellular calcium concentration in human distal colon

Recent studies from our laboratory have reported rapid (< 1 min) non-genomic activation of potassium recycling, Na+-H+ exchange, protein kinase C (PKC) activity and PKC-sensitive Ca2+ entry by mineralocorticoids in mammalian distal colonic epithelium. Previous studies from other laboratories have described stimulation of the Na+-H+ exchanger by PKC activation. Here a rapid non-genomic effect of aldosterone on PKC activity and intracellular free calcium [Ca2+]i is demonstrated in human distal colonic epithelium. Rapid activation (after 15 min incubation) of basal PKC activity was observed in cytosolic fractions of human colonic epithelium by aldosterone, fludrocortisone and deoxycorticosterone acetate (DOCA). PKC activation was inhibited by the specific PKC inhibitor bisindolylmaleimide (GF109203X). The glucocorticoid hydrocortisone failed to activate PKC activity. Aldosterone induced a rapid increase in [Ca2+]i in isolated human colonic crypts. This stimulatory effect on [Ca2+]i was inhibited by the PKC inhibitor chelerythrine chloride. Hydrocortisone and dexamethasone similarly failed to increase [Ca2+]i. These results indicate that intracellular signalling for aldosterone involves changes in [Ca2+]i via activation of PKC. Since stimulation of PKC activity and increase in [Ca2+]i are apparent at normal circulating levels of aldosterone, our findings may have important physiological implications and prompt a reassessment of mineralocorticoid effects on electrolyte homeostasis.

Targeted disruption of the mouse gene encoding steroidogenic acute regulatory protein provides insights into congenital lipoid adrenal hyperplasia

An essential component of regulated steroidogenesis is the translocation of cholesterol from the cytoplasm to the inner mitochondrial membrane where the cholesterol side-chain cleavage enzyme carries out the first committed step in steroidogenesis. Recent studies showed that a 30-kDa mitochondrial phosphoprotein, designated steroidogenic acute regulatory protein (StAR), is essential for this translocation. To allow us to explore the roles of StAR in a system amenable to experimental manipulation and to develop an animal model for the human disorder lipoid congenital adrenal hyperplasia (lipoid CAH), we used targeted gene disruption to produce StAR knockout mice. These StAR knockout mice were indistinguishable initially from wild-type littermates, except that males and females had female external genitalia. After birth, they failed to grow normally and died from adrenocortical insufficiency. Hormone assays confirmed severe defects in adrenal steroids-with loss of negative feedback regulation at hypothalamic-pituitary levels-whereas hormones constituting the gonadal axis did not differ significantly from levels in wild-type littermates. Histologically, the adrenal cortex of StAR knockout mice contained florid lipid deposits, with lesser deposits in the steroidogenic compartment of the testis and none in the ovary. The sex-specific differences in gonadal involvement support a two-stage model of the pathogenesis of StAR deficiency, with trophic hormone stimulation inducing progressive accumulation of lipids within the steroidogenic cells and ultimately causing their death. These StAR knockout mice provide a useful model system in which to determine the mechanisms of StAR's essential roles in adrenocortical and gonadal steroidogenesis.

Effect of fludrocortisone and spironolactone on sodium and potassium losses in secretory diarrhea

The response of the colon to aldosterone is believed to be an important adaptive mechanism to excessive sodium losses in diarrhea. However, the degree to which mineralocorticoid activity actually influences fecal output of sodium in people with diarrhea is unknown. To gain insight into this question, 10 normal people were treated with placebo, fludrocortisone (an aldosterone agonist), and spironolactone (an aldosterone antagonist) during three experimental periods lasting nine days. On days 5-8, diarrhea was induced by ingestion of phenolphthalein. Diet was controlled. Fecal sodium was 40 meq/day on placebo and 29 meq/day on fludrocortisone, consistent with mineralocorticoid stimulation of intestinal sodium absorption. However, contrary to our expectations, spironolactone therapy was also associated with a fall in fecal sodium output, to 28 meq/day. To explain this paradoxical effect of spironolactone, we suggest that sodium depletion caused by spironolactone's natriuretic action on the kidney caused the release of an unknown stimulant of intestinal sodium absorption, whose action more than overcame the reduced colonic absorption resulting from inhibition of aldosterone activity by spironolactone. This interpretation implies that the intestinal adaptation to sodium depletion in diarrhea involves both aldosterone and an aldosterone independent factor, working in concert to reduce fecal sodium output.

High plasma levels of endothelin-1 in untreated Addison's disease

The aim of this study has been to investigate the plasma endothelin-1 (ET-1) levels in adult patients with proven Addison's disease (AD). Plasma ET-1 levels were measured in 29 subjects (17 males and 12 females, aged between 20 and 54 years): 15 of them were patients with AD and 14 were sex- and age-matched normal subjects, used as a control group. All patients with AD have been studied under basal conditions and nine of them also after 2 weeks on oral corticosteroid therapy (individual cortisol dosage ranging from 25 to 37.5 mg/day and 0.1 mg/day 9 alpha-fluorohydrocortisone). Extracted plasma ET-1 was determined by a specific radioimmunoassay using rabbit endothelin antisera. Mean ET-1 values in the patients with AD were three times higher than in normal subjects (21.09 +/- 4.38 pg/ml vs 6.72 +/- 1.74 pg/ml; p < 0.0001). Plasma ET-1 levels assayed in the patients with AD after 2 weeks of corticosteroid therapy were significantly decreased (14.47 +/- 3.7 pg/ml vs 22.8 +/- 5.2 pg/ml; -37%; p < 0.001) compared to values in untreated patients. However, the plasma ET-1 values obtained following corticosteroid therapy were still significantly higher (p < 0.001) than those detected in the control subjects. These results clearly indicate that patients with untreated AD have increased circulating ET-1 levels that may be reduced by short-term corticosteroid therapy.

Rat 11 beta-hydroxysteroid dehydrogenase type 2 enzyme is expressed at low levels in the placenta and is modulated by adrenal steroids in the kidney

The 11 beta-hydroxysteroid dehydrogenase type II enzyme (11 beta HSD2) protects the non-discriminating mineralocorticoid receptor from occupation by glucocorticoids. In man the enzyme is also highly expressed in the placenta where it is thought to also protect the fetus from the high circulating levels of maternal glucocorticoids. Mutations in the HSD11B2 gene have recently been shown to account for the syndrome of apparent mineralocorticoid excess. In the present study we have used a rat 11 beta HSD2 cDNA to study the distribution and regulation of this enzyme. The rat protein is highly homologous to the mouse, rabbit and human enzymes, except for the carboxy-terminal region which displays extensive divergence between species beyond residue 382. Northern blot analysis of rat total RNA showed that the single copy gene is highly expressed in kidney and adrenal with lower levels in the colon; surprisingly, there was no detectable signal in the placenta. There was also no detectable mRNA in the liver, heart, hippocampus, testis, thymus and pancreas. Nuclease protection analysis revealed the presence of moderate 11 beta HSD2 message levels in the parotid and exceedingly low levels in the placenta. Regulation studies showed that administration of dexamethasone, deoxycorticosterone and 9 alpha-fluorocortisol to adrenalectomized rats for 7 days increased renal enzyme activity 33%-50%, while message levels decreased 35%-70%, suggesting that the increased enzyme activity may represent activation of latent enzyme.

Usefulness of tilt table test with normal saline infusion in management of neurocardiac syncope in children

Head-up tilt test has been useful in evaluating children with neurocardiac syncope. In this study patients with positive baseline and isoproterenol tests had repeat tilt testing done after normal saline infusion. If the symptoms persisted, the test was then repeated with phenylephrine infusion. Of the 101 patients studied, 58 (57%) had a positive tilt sign. Normal saline infusion was given to 53 patients. Three patients were excluded because of structural heart disease. Fifty patients (aged 14 +/- 4 years) comprised the study group. Forty-two (84%) of 50 patients had a negative repeat tilt sign after normal saline infusion, and these patients were treated with 0.5 to 1 gm of salt three times a day and/or fludrocortisone (20 patients). Of the 8 (16%) patients who did not respond to normal saline infusion, 5 had negative results when given phenylephrine and were treated with pseudoephedrine. Follow-up data on 42 patients (range 4 to 40 months, median 18 months) showed that all 35 patients who responded to normal saline were either asymptomatic or had improved. Two patients were successfully treated with pseudoephedrine; however, two patients in this group required pacemaker therapy. We conclude that (1) normal saline infusion mitigates the hemodynamic effects of neurocardiac syncope, (2) high-salt diet treatment in these patients was economical and effective, and (3) failure to respond to normal saline test may indicate a less favorable prognosis.

Determinants of cardiac fibrosis in experimental hypermineralocorticoid states

Uninephrectomized rats maintained on 1.0% NaCl to drink and infused with aldosterone (0.75 microgram/h) for 8 wk have previously been shown to develop hypertension, cardiac hypertrophy, and cardiac fibrosis. In the present study we have shown that K+ supplementation (1.0% NaCl plus 0.4% KCl drinking solution) alters neither the interstitial nor the perivascular fibrotic response to mineralocorticoid treatment. Second, rats receiving 0.75 microgram/h 9 alpha-fluorocortisol, a mineralocorticoid and glucocorticoid agonist, respond with hypertension and cardiac fibrosis without cardiac hypertrophy. Finally, intracerebroventricular infusion of the mineralocorticoid receptor antagonist RU-28318 blocks blood pressure elevation, but not cardiac hypertrophy or fibrosis, when aldosterone is coinfused peripherally. We conclude that the myocardial fibrosis observed in response to chronic mineralocorticoid elevation and salt loading is a humorally mediated event independent of hypokalemia, hypertension, and cardiac hypertrophy. It remains to be determined whether the fibrosis observed in the presence of excess salt represents a direct (e.g., cardiac) effect of mineralocorticoid hormones or one mediated via a primary action on classical epithelial aldosterone target tissues (e.g., kidney).

Effect of exogenous mineralocorticoid on platelet cytosolic calcium in normal humans

We tested the hypothesis that the fludrocortisone in doses sufficient to elevate blood pressure (BP) in normal subjects would increase platelet cytosolic calcium. Eight normal volunteers were given 0.8 mg fludrocortisone daily for 7 days (short protocol). Eight other normal volunteers ingested the drug for 6 weeks (long protocol). In the short protocol, fludrocortisone increased platelet cytosolic calcium and body weight by day 3, while BP was increased by day 7. In the long protocol, platelet cytosolic calcium was increased after 1 week, returned to basal values by 3 weeks and remained at that level for the rest of the study. Stimulation of the subjects' platelets ex vivo with thrombin and vasopressin led to a significant increase in intracellular free calcium concentration; however, fludrocortisone treatment did not alter the calcium response to either agonist. Fludrocortisone decreased serum potassium, plasma renin activity, plasma noradrenaline concentration and serum ionised calcium. These changes, as well as the BP increase, reverted to basal values when the drug was discontinued. We next incubated human platelets with fludrocortisone (1.4 nmol/l) and found a significant increase in cytosolic calcium by 30 min. The data suggest that a blood pressure-raising dose of mineralocorticoid leads to a transient (days to weeks) increase in platelet cytosolic calcium. Platelet cytosolic calcium and blood pressure are dissociated in that cytosolic calcium increases before the BP increase and later decreases to lower values, while the BP increase is sustained. Mineralocorticoid also has a direct effect on platelet cytosolic calcium in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenocortical steroids increase renal thiazide diuretic receptor density and response

The density of the rat renal pharmacologic receptor for thiazide-type diuretics, as quantitated by the maximal specific binding of (3H)metolazone, decreased to one-third normal after adrenalectomy. Selective glucocorticoid (dexamethasone or RU-28362) replacement increased thiazide receptor density to or above the normal level over the dose range of steroid that decreased thymus weight, which served as a bioassay for glucocorticoid activity. Mineralocorticoid (fludrocortisone or aldosterone), in doses that did not decrease thymus weight, also increased thiazide diuretic receptor density to or above normal. The addition of glucocorticoid (RU-28362) to maximal aldosterone increased thiazide receptor above that produced by aldosterone alone and to threefold normal. Similarly, the addition of aldosterone to high-dose RU-28362 also increased thiazide receptor density above that produced by the glucocorticoid alone and to threefold normal. Hence, the effects of glucocorticoids and mineralocorticoids appeared to be additive. The increase in renal thiazide receptor density produced by fludrocortisone, at a dose that elicited both mineralocorticoid and glucocorticoid effects, was unrelated to the basal (prethiazide) renal excretion of sodium, potassium, chloride, or calcium. However, fludrocortisone-pretreated animals responded to bendroflumethiazide with a greater natriuresis than did controls. In addition, the magnitudes of the thiazide-elicited natriuresis and chloriuresis correlated significantly with thiazide receptor. It was concluded that both the density of the renal thiazide receptor and the quantity of sodium and chloride reabsorbed by the thiazide-sensitive Na-Cl cotransporter in the kidney are under adrenocortical regulation.

Impaired renal 11 beta-oxidation of 9 alpha-fluorocortisol: an explanation for its mineralocorticoid potency

9 alpha-Fluorocortisol (9 alpha FF) is about 200 times more potent as a mineralocorticoid than cortisol (F) in man, although it binds with the same affinity as F and aldosterone to the human mineralocorticoid receptor. The low mineralocorticoid activity of F has been shown to be due to its rapid conversion by the kidney to cortisone (E), which does not bind to the receptor. Therefore, we compared the conversion of F to E with that of 9 alpha FF to 9 alpha-fluorocortisone (9 alpha FE) by 11-hydroxysteroid dehydrogenases in man in vivo and in vitro. Single oral doses of 9 alpha FF, 9 alpha FE, and F were given to normal males, and the excretion of free 9 alpha FF, 9 alpha FE, F, and E was measured in urine. Human kidney and liver slices were incubated with unlabeled steroids, and the free 11-hydroxy- and 11-oxosteroids were quantitated after high performance liquid chromatography separation by UV absorption. Oral F (5 mg) is excreted 70% as free E and 30% as free F (percentage of free steroids only). Oral 9 alpha FF (5 mg) is excreted 90% as free 9 alpha FF and 10% as free 9 alpha FE. Free 9 alpha FF excretion is 14 times greater than that of F after ingesting an identical dose. Oral 9 alpha FE (4 mg) is also excreted 90% as 9 alpha FF and 10% as 9 alpha FE. Kidney slices convert F much faster to E than 9 alpha FF to 9 alpha FE. The conversion of 9 alpha FE to 9 alpha FF is, on the contrary, much faster than that of E to F. Thus, the equilibrium of the reaction is on the 11-oxo side for F/E and on the 11-hydroxy side for 9 alpha FF/9 alpha FE. The interconversion of both pairs of steroids is inhibited by glycyrrhetinic acid in a dose-dependent manner. Liver slices do not measurably convert 9 alpha FF to 9 alpha FE, but do rapidly convert 9 alpha FE into 9 alpha FF. Reflecting this negligible conversion of 9 alpha FF to 9 alpha FE and the low plasma-protein binding of 9 alpha FF, free urinary 9 alpha FF excretion is much higher than that of F after the same oral dose.(ABSTRACT TRUNCATED AT 400 WORDS)

[Pharmacological action of 9alpha-fluorohydrocortisone as a mineralocorticoid]

The action of 9 alpha-fluorohydrocortisone (fludrocortisone) as a potent mineralocorticoid was reviewed. Fludrocortisone shows mineralocorticoid activity as potent as aldosterone and causes sodium-retention and kaliuresis when injected intravenously in man. The duration of the action of fludrocortisone in longer than that of aldosterone. Therefore, fludrocortisone is more pertinent to clinical use than aldosterone. Fludrocortisone is administered as a mineralocorticoid in case of Addison's disease and postoperative Cushing syndrome. It is also used to relieve hyperkalemia or to ameliorate hyponatremia.