Increased Aldosterone Secretion Research Articles

Fatty acids as a direct regulator of aldosterone hypersecretion

Primary hyperaldosteronism is a major cause of secondary hypertension and carries additional cardiovascular risks beyond that of the elevated blood pressure. Primary hyperaldosteronism is more prevalent in obese people, and weight loss reduces aldosterone levels. It needs to be determined whether obesity related factors directly contribute to the pathogenesis of primary hyperaldosteronism. Here we show that the non-esterified fatty acids (NEFA) palmitic acid, and to a lesser extent, linoleic acid significantly stimulated aldosterone production and steroid enzyme induction in adrenocortical HAC15 cells of human origin. Palmitic acid, linoleic acid, and to a much lesser extent, oleic acid induced the expression of aldosterone synthase. Induction of the Steroidogenic Acute Regulatory Protein (StAR) was modest. Increased aldosterone secretion was independent of fatty acid beta-oxidation in the mitochondria but may involve free fatty acid receptor 1 (FFAR1/GPR40) and endoplasmic reticulum (ER) stress. Palmitic acid and linoleic acid induced the expression of C/EBP Homologous Protein (CHOP), a marker of ER stress, correlating with their ability to induce aldosterone synthase gene expression. Palmitic acid, but not linoleic acid decreased mitochondrial potentials and induced uncoupling protein 2 (UCP2). Palmitic acid enhanced, while docosahexaenoic acid (DHA) suppressed aldosterone response to angiotensin II (Ang-II). Our study provides evidence that NEFAs modulate aldosterone production, and further suggests that hyperaldosteronism shares similar pathogenesis with other obesity-related disorders such as metabolic syndrome.

Does COVID-19 cause pre-eclampsia?

Does COVID-19 cause pre-eclampsia?

Genetic Predictors of Salt Sensitivity of Blood Pressure: The Additive Impact of 2 Hits in the Same Biological Pathway.

[Figure: see text].

Case Report: Newborns With Pseudohypoaldosteronism Secondary to Excessive Gastrointestinal Losses Through High Output Stoma

Life-threatening electrolyte imbalance is not uncommon in preemies. Differential diagnosis is important for immediate treatment. The syndrome of pseudohypoaldosteronism (PHA) is characterized by increased aldosterone secretion associated with clinical signs of hypoaldosteronism reflecting mineralocorticoid resistance. There are type I, type II, and secondary type of PHA. Most secondary PHA reported in the pediatric population result from urinary infection and obstructive uropathy and extremely rarely from gastrointestinal fluid loss. Seven preemies accepted jejunostomy or ileostomy, and they suffered from high output stoma. Electrolyte imbalance with bodyweight loss or cardiac event was noted. We found a high level of aldosterone and renin and diagnosed them with secondary PHA due to excessive gastrointestinal losses. After stomal reversal, aldosterone and renin level became normalized, and electrolyte was corrected. This study reports the finding of secondary pseudohyperaldosteronism (hyponatremia, hyperkalemia, and metabolic acidosis) in a series of cases with intestinal resection and ostomy of different causes. Early stomal reversal was recommended.

Somatic Mutations of GNA11 and GNAQ in CTNNB1-Mutant Aldosterone-Producing Adenomas Increases Aldosterone and Aldosterone Synthase (CYP11B2)

Abstract Most aldosterone-producing adenomas (APA) have gain-of-function somatic mutations of ion channels or transporters. However, their frequency in aldosterone-producing cell-clusters of normal adrenals suggests the existence of co-driver mutations which influence the development or phenotype of APAs. Gain-of-function mutations in both CTNNB1 and GNA11 were found by whole exome sequencing in 3 of 41 APAs from a UK/Irish cohort. Targeted sequencing for exon 3 mutations of CTNNB1 and p.Gln209 mutations of either GNA11 or closely homologous GNAQ confirmed these and 7 further double mutant APAs in this discovery cohort. The presence of GNA11/Q p.Gln209 mutations in CTNNB1 mutant APAs were replicated in 2 cohorts from France (n=14) and Sweden (n=3). In total, 16 (59%) of the 27 CTNNB1 mutant APAs investigated had a mutation at p.Gln209 of GNA11 (n=11) or GNAQ (n=5). Interestingly, CTNNB1-mutant APAs were more commonly present in women (23/27), and of these, those with GNA11/Q mutations were all women except for a pubertal boy. To also note, 9 of 10 of the UK/Irish double mutant APAs in the discovery cohort presented in puberty, pregnancy, or menopause. Mutation of p.Gln209, or homologous p.Gln in GNAS, GNA12-14, impair hydrogen bonds between G-protein α and β subunits. Transfection of H295R cells, an immortalised adrenocortical cell line heterozygous for the p.Ser45Pro mutation of CTNNB1 but wild-type for GNA11-14/Q/S, by each of the GNA11/Q mutations increased aldosterone secretion and CYP11B2 expression (encoding aldosterone synthase) by 1.93-6.1-fold and 8.0-9.8-fold respectively, compared to vector or wild-type -transfected cells. In ZG, GNA11/Q mediate the aldosterone response to angiotensin II, via stimulation of intracellular Ca2+ release by inositol trisphosphate. In the mutant-transfected cells, the stimulatory effect of angiotensin II 10 nM was retained. In order to determine whether the p.Gln209 mutations stimulate aldosterone production even in the absence of CTNNB1 activation, the transfections of H295R cells were repeated after either 24-h treatment with the CTNNB1 inhibitor, ICG-001, or silencing of CTNNB1 using the ONTARGETplus SMARTpool SiRNAs (Dharmacon). Both interventions reduced the aldosterone production relative to vehicle/control-treated cells; however neither ICG-001 nor silencing of CTNNB1 blunted the fold-increase in aldosterone secretion seen in mutant-transfected cells compared to wild-type. In summary, we report the discovery of gain-of-function mutations of the G-protein, GNA11, or its close homologue, GNAQ, in multiple APAs which majority presented during periods of high LH/HCG. To date, the mutation is always residue p.Gln209, and associated with a gain-of-function mutation of CTNNB1. These GNA11/Q p.Gln209 mutations increase aldosterone and CYP11B2 production both in the presence and in the absence of CTNNB1 activation.

Enzym konwertujący angiotensynę 2 (ACE2) – główny receptor dla wirusa SARS-CoV-2

The renin-angiotensin-aldosterone system (RAS) plays a significant role in the regulation of the water and electrolyte balance. Renin from the kidneys converts angiotensinogen to angiotensin I. Angiotensin converting enzyme (ACE) catalyzes the conversion of angiotensin I to angiotensin II. The activation of AT1 receptors by angiotensin II causes vasoconstriction, an increase in aldosterone secretion, and an increase in the reabsorption of sodium ions in nephrons, leading to elevation of the blood pressure. Angiotensin II promotes oxidative stress, growth and proliferation of cells, stimulates coagulation, inhibits fibrinolysis, and intensifies inflammatory processes. The ACE-angiotensin II-AT1R pathway is balanced by angiotensin converting enzyme 2 (ACE2), which degrades angiotensin I to angiotensin (1-9) and angiotensin II to angiotensin (1-7). Angiotensin (1-7) and angiotensin (1-9) pathways exert protective effects by activating, respectively Mas and AT2 receptors. ACE and ACE2 also have intimate roles with the plasma kallikrein-kinin system (KKS), a hormonal pathway that modulates the intrinsic blood coagulation system, endothelial cell growth and angiogenesis, the complement pathway and RAS. The appearance in Wuhan, China, of the first cases of SARS-CoV-2 infections at the end of 2019 launched a series of intensive studies, which proved that the virus invades host cells using ACE2 as a specific receptor. This survey presents basic information on the structure and tissue distribution of ACE2 and the role this enzyme plays in pathogenesis of COVID-19. A particular emphasis is given to pathophysiological effects of the functional superiority of the ACE → angiotensin II → AT1 receptor axis over the pathway ACE2 → angiotensin II → angiotensin (1-7) → Mas receptor. Such disharmony is a consequence of SARS-CoV-2 induced ACE2-downregulation. In the era of the expanding COVID-19 pandemic, intensive research is conducted not only on vaccines and antiviral drugs, but also on compounds that can restore the functional balance between angiotensin II and angiotensin (1-7). © 2021 Polish Pharmaceutical Society. All rights reserved.

Amphetamine Stimulates Protein Kinase and Calcium Influx to Increase Corticosterone and Aldosterone Secretion from Male Rat Adrenal Cells

Amphetamine is a potent central nervous system stimulant. Clinical trials have demonstrated that in healthy adults, low (therapeutic) doses of amphetamine can improve i.e., cognition, memory, attention behavior. An amphetamine overdose can affect cardiovascular, central nervous system, musculoskeletal, respiratory, urinary, or sexual function. Furthermore, amphetamine can activate the hypothalamic-pituitary-adrenal axis to increase glucocorticoids and mineralocorticoids released from adrenal. The object of this research was to find out the effect of amphetamine in vivo and in vitro on the production of corticosterone and aldosterone by Zona Fasciculata-Reticularis (ZFR) cells and Zona Glomerulosa (ZG) cells from male rats. For the in vivo study, the rats were given intraperitoneal injections of saline (1 ml/kg/day, group 1), amphetamine (1 mg/ml/kg/day, group 2), or amphetamine (5 mg/ml/kg/day, group 3) for 7 days and then the ZFR or ZG cells from the sacrificed rats were incubated with other drugs. For the in vitro study, the adrenal cells of ZFR or ZG from untreated rats were incubated with amphetamine combined with other drugs. The corticosterone and aldosterone concentrations in samples of the medium were measured using radioimmunoassay. This in vitro and in vivo study illustrated that amphetamine can increase corticosterone secretion by ZFR cells and aldosterone secretion by ZG cells from male rats.

Masked Uncontrolled Hypertension Is Accompanied by Increased Out-of-Clinic Aldosterone Secretion.

Masked uncontrolled hypertension (MUCH) in treated patients is defined as controlled office blood pressure (BP) but uncontrolled out-of-clinic ambulatory BP. Previously, we have shown that patients with MUCH have evidence of heightened out-of-clinic sympathetic nervous system activity. The aim is to test the hypothesis that MUCH patients have higher aldosterone secretion compared with patients with true controlled hypertension. Two hundred twenty-two patients were recruited after having controlled office BP readings at ≥3 clinic visits. Patients taking MR (mineralocorticoid receptor) antagonists and epithelial sodium channel blockers were excluded. All patients were evaluated by clinic automated office BP and morning serum aldosterone and plasma renin activity. Out-of-clinic ambulatory BP monitoring and 24-hour urinary aldosterone, catecholamines, and metanephrines were also measured. Sixty-four patients had MUCH, and the remaining 48 patients had true controlled hypertension. MUCH patients had significantly higher out-of-clinic levels of 24-hour urinary aldosterone, catecholamines, and metanephrines compared with true controlled hypertension. The 2 groups did not differ in serum aldosterone, plasma renin activity, or aldosterone-renin ratio collected in clinic. In addition, 32.8% of MUCH patients had high out-of-clinic 24-hour urinary aldosterone (≥12 µg) but normal clinic serum aldosterone (<15 ng/dL) and aldosterone-renin ratio (<20). Further, in correlation matrix analysis, higher 24-hour urinary catecholamines and metanephrines were associated with higher 24-hour urinary aldosterone and plasma renin activity levels in MUCH patients. Patients with MUCH have higher out-of-clinic urinary aldosterone levels compared with patients with true controlled hypertension. This study suggests that patients with MUCH likely have higher out-of-clinic sympathetic nervous system tone increases aldosterone secretion mediated by increased renin release that may contribute to their higher out-of-clinic BP.

OR34-02 Somatic Transmembrane Domain Mutations of a Cell Adhesion Molecule, CADM1, Cause Primary Aldosteronism by Preventing Gap Junction Communication Between Adrenocortical Cells

Primary Aldosteronism (PA) is the commonest curable cause of hypertension. Whole exome sequencing (WES) in 2011 and 2013 identified common somatic mutations in genes regulating membrane polarisation in 60–80% of aldosterone-producing adenomas (APA). We undertook WES on 39 consecutive APAs in search of further variants. 1 APA revealed a somatic mutation (Val380Asp) within the single transmembrane domain of Cell Adhesion Molecule 1 (CADM1). An adjacent mutation (Gly379Asp) was discovered on WES from a PA patient in Munich.Both short and long isoforms (442 & 453 residues) of wild-type (WT) and both mutant CADM1 genes were cloned into lentivirus vectors and each transduced into adrenocortical (H295R) cells to assess its effect on aldosterone secretion and other parameters. Previous studies in pancreatic islet cells suggested a role of CADM1 in regulating gap junction (GJ) communication. To assess this we microinjected single WT or mutant H295R cells with the GJ permeable dye calceinAM and counted the dye-positive cells after 1 hour. The effect of inhibiting or silencing GJs in H295R cells using peptide gap27 or a Dharmacon smartpool was assessed. H295R cells were also co-transfected with WT or mutant CADM1 and the GJ protein CX43, tagged with the mApple fluorophore. These were mixed with cells transfected with CX43-Venus, allowing confocal visualisation of GJ formation. Protein modelling was undertaken to determine whether Asp in the intramembranous domain changes angulation of CADM1.All mutant isoforms had consistently different effects, shown as a range compared to WT. Cells transduced with mutant CADM1 showed 3-6-fold increase in aldosterone secretion (p<0.01) and 10-20-fold increase in CYP11B2 expression (p<0.001) compared to WT. Dye transfer assays showed paucity of dye transfer between neighbouring mutant CADM1 cells, while calcein passed easily through GJs in WT cells. CX43 inhibition increased aldosterone secretion 2-fold (p<0.01), and CYP11B2 expression 3 to 8-fold (<0.001). Knock-down of GJ proteins increased aldosterone secretion 1.5-fold (p<0.01) and CYP11B2 expression 1.7-fold (p<0.001).Protein modelling showed mutations to increase the angle of ectodomains to cell membrane, from 49o in WT cells, to 62o and 90o in Gly379Asp and Val380Asp respectively; increasing inter-cell distance from 21.2nm to 24.7 and 27.9nm. Mixing of Venus and mApple-tagged CX43 transfected cells showed fewer intact GJ channels in cells co-transfected with mutant compared to WT CADM1 [mutant 42/291 (14.4%) VS WT 68/212 (32.1%) p<0.001].The CADM1 mutations shows the importance of membrane proteins in aldosterone regulation to extend beyond ion channels and transporters. A key role may be to bring opposing CX43 hemichannels close enough to form GJ channels, permitting the oscillating Ca2+ currents which regulate aldosterone in intact adrenal slices.

SAT-224 Recurrent Co-Driver Mutation in CTNNB1-Mutant Aldosterone-producing Adenomas (APA), Causing Reversible Hypertension in Puberty, Pregnancy or Menopause

Background: Three patients with a syndrome of LH/HCG-activated primary aldosteronism in pregnancy or menopause carrying somatic CTNNB1 mutations were reported four years ago (Teo et al. NEJM 2015). This proved but half the story. Diagnosis of an APA in a 12-year old boy with severe hypertension revealed an apparently essential co-driver mutation. Methods: WES of tumour and blood was performed in the pubertal boy. Candidate genes were Sanger sequenced in other APAs from GB/Ireland, and France with known or suspected CTNNB1 mutations. LHCGR, GNRHR and CYP11B2 expression were measured in all available patients’ APAs and the adjacent adrenal gland (AAG) by RT-PCR. RNA and gDNA from the zona glomerulosa (ZG) of the proband’s AAG were collected by laser capture microdissection for Sanger sequencing of GNA11 and CTNNB1. Function of mutant genes was assessed by measurement of aldosterone production and LHCGR expression by immunofluorescence (IFC) in NCI-H295R adrenocortical cells and primary human APA cells. Results: The proband’s APA contained a p.(S45F) somatic mutation in CTNNB1, and a p.(Q209P) somatic mutation of the GTPase-activating residue (Q209) in GNA11. Mutations of Q209, to P or H, were also found in six other GB/Irish patients with previously identified mutations of CTNNB1 (S33C, G34R, T41A, S45F, or S45P). All seven patients remain normotensive 2-12 years post-adrenalectomy, including some with long-standing pre-operative hypertension. Four of the 13 French patients with CTNNB1 exon 3 mutant APAs have somatic mutation of Q209 of either GNA11 (n=3) or GNAQ. In comparison with their own AAG, the GB/Irish double mutant APAs showed an increase in expression of LHCGR, CYP11B2 and GNRHR by 32-166, 158-18980, and 1174-6642 fold, respectively. All four French double-mutants had >10 fold higher LHCGR than APAs with single mutations of CTNNB1 or other genes. Hyperplasia of ZG was observed in the ZG of the boy’s AAG but no APCC was detected. Homozygous or heterozygous Q209P mutation of GNA11 was detected in multiple ZG samples in RNA and/or gDNA but WT in CTNNB1 exon 3. H295R cells (CTNNB1 S45P) were GNA11 WT. Overexpression of GNA11 Q209 mutation increased aldosterone secretion to 465% of GNA11 WT overexpressing cells (n=6, P<0.001) and CYP11B2 expression was also increased several-fold. Smaller increases were seen in primary human adrenal cells after double-transfection by GNA11 and CTNNB1 mutants (n=3, P<0.001). This also caused membrane expression of LHCGR, visualised by IFC. Conclusions: APAs with double mutation of GNA11/GNAQ Q209 and CTNNB1 have a distinct phenotype, in which hypertension is triggered by high LH or HCG, and cured in all cases by adrenalectomy. GNA11/Q mediates the aldosterone response to ANGII, and the Q209 codon is analogous to the Q227 of GNAS, mutated in McCune Albright. Mosaicism for GNA11 may cause ZG hyperplasia.

COVID-19, diabetes mellitus and ACE2: The conundrum

COVID-19, diabetes mellitus and ACE2: The conundrum

Resistant Hypertension: Diagnosis and Management.

Resistant hypertension is defined as high blood pressure requiring 3 or more medications for adequate control or controlled blood pressure requiring 4 or more medications. Considering the growing prevalence of hypertension and the strong link with cardiovascular disease, it is vital to understand the causes and treatment of resistant hypertension. This review article starts with an overview of the prevalence and little-known pathophysiology of resistant hypertension. Afterward, we discuss the evaluation and management of suspected secondary resistant hypertension in 2 broad categories: pseudoresistant hypertension and true resistant hypertension. Strategies for the identification and management of pseudoresistant hypertension are addressed. In addition, causes of true resistant hypertension, such as obstructive sleep apnea, primary aldosteronism, and renal artery stenosis, are examined along with their respective treatments. Finally, treatment of resistant hypertension is reviewed including pharmacologic treatments and novel procedural interventions for resistant hypertension. Overall, the review hopes to provide practitioners with a cohesive approach for the diagnosis and treatment of resistant hypertension.

GSTA1 Expression Is Correlated With Aldosterone Level in KCNJ5-Mutated Adrenal Aldosterone-Producing Adenoma.

KCNJ5 mutation is a major cause of aldosterone-producing adenomas (APAs). The development of APA apart from KCNJ5 mutation is less investigated. To investigate other mechanisms affecting aldosterone secretion apart from KCNJ5. Six pairs of KCNJ5-mutated, high and low aldosterone-secreting APAs, five non-KCNJ5-mutated APAs, and four normal adrenal glands were assayed by Affymetrix GeneChip Human Transcriptome Array 2.0. A total of 113 APA samples were investigated to explore the expression of glutathione-S-transferase A1 (GSTA1). H295R cells were used to verify the function of GSTA1. GSTA1 was the top gene downregulated in high-aldosterone KCNJ5-mutated APAs. GSTA1 was also downregulated in KCNJ5-mutated APAs compared with wild-type KCNJ5 APAs. Accordingly, mutant KCNJ5 decreased GSTA1 messenger RNA and protein expression levels. GSTA1 overexpression suppressed aldosterone secretion whether in wild-type or mutant KCNJ5 H295R cells. Adding ethacrynic acid or silencing of GSTA1 increased aldosterone secretion by increasing reactive oxygen species (ROS), superoxide, H2O2 levels, and Ca2+ influx. The expression of the transcription factors NR4A1, NR4A2, and CAMK1 and intracellular Ca2+ were significantly upregulated by GSTA1 inhibition. The reduced form of NAD phosphate oxidase inhibitor or H2O2 scavenger or blocking calmodulin or calcium channels could significantly reduce aldosterone secretion in GSTA1-inhibited cells. (1) GSTA1 expression is reversely correlated with aldosterone level in KCNJ5-mutated APAs, (2) GSTA1 regulates aldosterone secretion by ROS and Ca2+ signaling, and (3) KCNJ5 mutation downregulates GSTA1 expression, and overexpression of GSTA1 reverses increased aldosterone in KCNJ5-mutated adrenal cells.

Discovery of a Novel Piperidine-Based Inhibitor of Cholesteryl Ester Transfer Protein (CETP) That Retains Activity in Hypertriglyceridemic Plasma.

Herein we describe the discovery and characterization of a novel, piperidine-based inhibitor of cholesteryl ester transfer protein (CETP) with a core structure distinct from other reported CETP inhibitors. A versatile synthesis starting from 4-methoxypyridine enabled an efficient exploration of the SAR, giving a lead molecule with potent CETP inhibition in human plasma. The subsequent optimization focused on improvement of pharmacokinetics and mitigation of off-target liabilities, such as CYP inhibition, whose improvement correlated with increased lipophilic efficiency. The effort led to the identification of an achiral, carboxylic acid-bearing compound 16 (TAP311) with excellent pharmacokinetics in rats and robust efficacy in hamsters. Compared to anacetrapib, the compound showed substantially reduced lipophilicity, had only modest distribution into adipose tissue, and retained potency in hypertriglyceridemic plasma in vitro and in vivo. Furthermore, in contrast to torcetrapib, the compound did not increase aldosterone secretion in human adrenocortical carcinoma cells nor in chronically cannulated rats. On the basis of its preclinical efficacy and safety profile, the compound was advanced into clinical trials.

Obesity-stimulated aldosterone release is not related to an S1P-dependent mechanism.

Aldosterone has been identified as an important factor in obesity-associated hypertension. Here, we investigated whether sphingosine-1-phosphate (S1P), which has previously been linked to obesity, increases aldosterone release. S1P-induced aldosterone release was determined in NCI H295R cells in the presence of S1P receptor (S1PR) antagonists. In vivo release of S1P (100-300 µg/kgbw) was investigated in pithed, lean Sprague Dawley (SD) rats, diet-obese spontaneous hypertensive rats (SHRs), as well as in lean or obese Zucker rats. Aldosterone secretion was increased in NCI H295R cells by S1P, the selective S1PR1 agonist SEW2871 and the selective S1PR2 antagonist JTE013. Treatment with the S1PR1 antagonist W146 or fingolimod and the S1PR1/3 antagonist VPbib2319 decreased baseline and/or S1P-stimulated aldosterone release. Compared to saline-treated SD rats, plasma aldosterone increased by ~50 pg/mL after infusing S1P. Baseline levels of S1P and aldosterone were higher in obese than in lean SHRs. Adrenal S1PR expression did not differ between chow- or CD-fed rats that had the highest S1PR1 and lowest S1PR4 levels. S1P induced a short-lasting increase in plasma aldosterone in obese, but not in lean SHRs. However, 2-ANOVA did not demonstrate any difference between lean and obese rats. S1P-induced aldosterone release was also similar between obese and lean Zucker rats. We conclude that S1P is a local regulator of aldosterone production. S1PR1 agonism induces an increase in aldosterone secretion, while stimulating adrenal S1PR2 receptor suppresses aldosterone production. A significant role of S1P in influencing aldosterone secretion in states of obesity seems unlikely.

Up-regulation of claudin-2 expression by aldosterone in colonic epithelial cells of mice fed with NaCl-depleted diets

Dietary NaCl depletion increases Na+ absorption and K+ secretion in the colon, but the mechanisms are not fully understood. In mice fed with NaCl-depleted diets, the expression of claudin-2 and -7 increased compared to those in control mice. Aldosterone (ALD) concentration was also increased. We examined the regulatory mechanism of claudin expression by ALD using the murine colonic epithelial MCE301 cells. ALD dose-dependently increased claudin-2 expression without affecting the expression of claudin-4, -7, -8, and -15. ALD increased nuclear distribution of mineralocorticoid receptor (MR), which was inhibited by spironolactone, an MR antagonist. The ALD-induced elevation of claudin-2 mRNA and protein expression was inhibited by spironolactone, but not by RU-486, a glucocorticoid receptor antagonist. Luciferase reporter assay showed that ALD interacts with the promoter region between -2,021 and -2,008 of human claudin-2. The binding of MR on the promoter region of claudin-2 was increased by ALD, which was inhibited by spironolactone in chromatin immunoprecipitation assay. Our data suggest that ALD acts on MR and increases paracellular permeability to ions mediated by the elevation of claudin-2 expression in the colon. NaCl depletion may increase ALD secretion from adrenal cortex, resulting in the elevation of paracellular permeability to cations in the colon.

Abstract P274: Double Hit! A Unique Case of Resistant Hypertension

Case Description: A 52 year-old woman with obesity, HLD, diet-controlled diabetes was referred for resistant hypertension. Her blood pressure (BP) was uncontrolled (systolic 145-200 mmHg, diastolic 95-135 mmHg) on 5 medications. Physical exam revealed a systolic ejection murmur at the base. An ECHO showed normal systolic function and moderate LVH. Plasma aldosterone was 20.7 ng/dL (normal 3-15 g/dL), plasma renin was 0.50 ng/mL/h (normal 0.65-5.0 ng/mL/h), and aldosterone:renin ratio was 41.4 [ng/dL]/[ng/mL/h], meeting criteria for Primary Aldosteronism (PA). Saline infusion test was confirmatory for PA. CT scan of the adrenals did not reveal an adenoma. Subsequent Adrenal Venous Sampling confirmed bilateral Idiopathic Adrenal Hyperplasia (IAH; right and left adrenal vein selectivity index of 42.6, 9.2 respectively; lateralization index was 1.3). She was normokalemic (3.7-4.4 mEq/L), total calcium (Ca) was 11.2 mg/dL (normal Ca 8.0-10.4), and creatinine was 1.4 mg/dL (GFR 47 mL/min/1.73m 2 ). Intact parathyroid hormone (iPTH) was 131.2 pg/mL, phosphorus was 2.4 mg/dL, and 25-hydroxyvitamin D was 30.8 ng/mL, suggesting primary hyperparathyroidism (PPTH). Neck ultrasound was concerning for PTH adenoma and sestamibi scan localized a left adenoma. DXA scan and renal ultrasound were normal. IAH was treated medically with spironolactone. Her BP remained elevated (systolic 138-172 mmHg, diastolic 92-100 mmHg). She underwent parathyroidectomy and histology confirmed an adenoma. Post-operative iPTH and Ca normalized (49.5 pg/mL, 9.7 mg/dL respectively). Postoperative BP measurements improved (systolic 123-138 mmHg, diastolic 75-86 mmHg). Discussion: Evidence shows that a hyperfunctioning parathyroid gland may contribute to maintaining hyperaldosteronism in PA. This is based on in-vitro studies showing PTH increased aldosterone secretion from adrenocortical cells in a concentration dependent manner. Gene expression and immunohistochemistry studies show PTH receptors in aldosterone-producing adenomas and MR receptors in parathyroid cells, suggesting a bi-directional relationship. The significance of this case is in the potential for further understanding of the pathophysiology of common causes of secondary hypertension.

JS ISH-ECCR-4 THE PLASMA ALDOSTERONE / ANGIOTENSIN II RATIO FOR THE SCREENING OF SECONDARY HYPERTENSION

Primary aldosteronism (PA) is severe form of hypertension characterized by a strongly increased aldosterone secretion mediated by adenomas or other forms of adrenal hyper-activity. Once detected, PA can be usually cured by either surgical intervention or by appropriate pharmacologic treatments. The incidence of PA among hypertensive patients varies strongly between different studies, which is in part caused by the complex state-of-the-art testing procedure that is unfortunately far away from being a versatile PA screening tool. Despite strong limitations regarding selectivity and the interference with multiple anti-hypertensive drugs, the antibody-based determination of the aldosterone-renin-ratio (ARR) is widely used in the diagnostic process of PA. However, there is still a strong demand for accurate, reliable and patient friendly PA case detection. The implementation of novel LC-MS/MS based assays for quantification of aldosterone might help to improve the power of the ARR as a diagnostic tool for PA. However, there is a big need for a versatile PA screening test that doesn’t interfere with anti-hypertensive treatments and therefore allows the clear identification of PA patients without complex and risky treatment adaptions being necessary in the course of the diagnostic process. The Aldosterone-to-Angiotensin-II-Ratio (AA2-Ratio) is a novel LC-MS/MS based high-throughput test for PA that combines the molar plasma levels of aldosterone and physiologically active angiotensin II into a single dimension-free diagnostic value. The availability of innovative diagnostic approaches for biochemical analysis of the Renin-Angiotensin-Aldosterone-System paved the way for Angiotensin peptides to be used in clinical routine testing by overcoming pre-analytic issues regarding analyte stability. In addition to overall RAS activity and aldosterone levels, the AA2-Ratio integrates the activity of all plasma enzymes involved in angiotensin II metabolism and accurately estimates of the portion of physiologically active angiotensin II in a patient sample. The performance of the AA2-Ratio is superior to the ARR in terms of the diagnostic window, which can be explained by the much closer functional link between aldosterone and angiotensin II comparing to the molecular distant relationship between aldosterone and renin. It has been shown that the correlation between renin concentration or activity and angiotensin II is poor especially in patients treated with anti-hypertensive drugs. In sharp contrast, the AA2-Ratio does not interfere with first line anti-hypertensive drugs including ACE inhibitors. The AA2-Ratio has the potential to be superior to the ARR in terms of its ability to better reflecting the activity of the true direct circulating regulator of aldosterone (i.e. angiotensin II rather than renin), and being unaffected by antihypertensive medications including ACE inhibitors. Data obtained in proof-of-concept studies proved the AA2-Ratio to be a powerful and cost-effective diagnostic tool for the diagnosis of PA among hypertensive patients. The stability of the AA2-Ratio in the presence of ACE-inhibition points to a potential use of the AA2-Ratio PA screening in hypertensive patients without ACE-inhibitor discontinuation.

Small-Conductance Ca2+-Activated Potassium Channels Negatively Regulate Aldosterone Secretion in Human Adrenocortical Cells.

Aldosterone, which plays a key role in maintaining water and electrolyte balance, is produced by zona glomerulosa cells of the adrenal cortex. Autonomous overproduction of aldosterone from zona glomerulosa cells causes primary hyperaldosteronism. Recent clinical studies have highlighted the pathological role of the KCNJ5 potassium channel in primary hyperaldosteronism. Our objective was to determine whether small-conductance Ca(2+)-activated potassium (SK) channels may also regulate aldosterone secretion in human adrenocortical cells. We found that apamin, the prototypic inhibitor of SK channels, decreased membrane voltage, raised intracellular Ca(2+) and dose dependently increased aldosterone secretion from human adrenocortical H295R cells. By contrast, 1-Ethyl-2-benzimidazolinone, an agonist of SK channels, antagonized apamin's action and decreased aldosterone secretion. Commensurate with an increase in aldosterone production, apamin increased mRNA expression of steroidogenic acute regulatory protein and aldosterone synthase that control the early and late rate-limiting steps in aldosterone biosynthesis, respectively. In addition, apamin increased angiotensin II-stimulated aldosterone secretion, whereas 1-Ethyl-2-benzimidazolinone suppressed both angiotensin II- and high K(+)-stimulated production of aldosterone in H295R cells. These findings were supported by apamin-modulation of basal and angiotensin II-stimulated aldosterone secretion from acutely prepared slices of human adrenals. We conclude that SK channel activity negatively regulates aldosterone secretion in human adrenocortical cells. Genetic association studies are necessary to determine whether mutations in SK channel subtype 2 genes may also drive aldosterone excess in primary hyperaldosteronism.

Editorial: Adrenal Cortex: From Physiology to Disease

Editorial: Adrenal Cortex: From Physiology to Disease