Dopaminergic Regulation of Aldosterone Secretion in Primary Aldosteronism: A Clinical Study.

AbstractThe diagnostic workup for primary aldosteronism includes a screening step using the aldosterone-to-renin ratio (ARR) and a confirmatory step based on dynamic testing of aldosterone secretion autonomy. International guidelines suggest that precise clinical and biochemical conditions may allow the bypassing of the confirmatory step, however, data which validate hormone thresholds defining such conditions are lacking. At our tertiary center, we retrospectively examined a cohort of 173 hypertensive patients screened for PA by the ARR, of whom 120 had positive screening and passed a saline infusion test (SIT) or a captopril challenge test (CCT). Fifty-nine had PA, including 34 Conn adenomas and 25 with idiopathic aldosteronism (IA). Using a threshold of 160 pmol/l, post-SIT plasma aldosterone concentration (PAC) identified PA with 86.4% sensitivity, 94.7% specificity, and a negative predictive value of 92.3%. Of those subjects with a high ARR and a PAC above 550 pmol/l, 93% had a positive SIT, while 100% of subjects with a high ARR, but a PAC under 240 pmol/l had a negative SIT. Our results thus validate the biochemical conditions defined in the French and US guidelines for bypassing the confirmatory step in the workup for PA diagnosis.

Download Full-text

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

Journal of the Endocrine Society ◽

10.1210/jendso/bvaa046.492 ◽

2020 ◽

Vol 4 (Supplement_1) ◽

Author(s):

Xilin Wu ◽

Sumedha Garg ◽

Claudia P Cabrera ◽

Elena Azizan ◽

Junhua Zhou ◽

...

Keyword(s):

Cell Adhesion ◽

Adhesion Molecule ◽

Primary Aldosteronism ◽

Cell Adhesion Molecule ◽

Transmembrane Domain ◽

Fold Increase ◽

Protein Modelling ◽

Dye Transfer ◽

Aldosterone Secretion ◽

H295r Cells

Abstract 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.

Download Full-text

Prevalence of Primary Aldosteronism Across the Stages of Hypertension Based on a New Combined Overnight Test

Hormone and Metabolic Research ◽

10.1055/a-1507-5226 ◽

2021 ◽

Vol 53 (07) ◽

pp. 461-469

Author(s):

Nick Voulgaris ◽

Ernestini Tyfoxylou ◽

Sophia Vlachou ◽

Evagelia Kyriazi ◽

Chris Gravvanis ◽

...

Keyword(s):

Arterial Hypertension ◽

Primary Aldosteronism ◽

Adrenocorticotropic Hormone ◽

Stage I ◽

Aldosterone Secretion ◽

Hypertensive Patients ◽

True Prevalence ◽

Normal Limits ◽

Aldosterone To Renin Ratio ◽

A Prospective Study

AbstractPrimary aldosteronism (PA) is the most common endocrine cause of arterial hypertension. Despite the increasing incidence of hypertension worldwide, the true prevalence of PA in hypertension was only recently recognized. The objective of the work was to estimate the prevalence of PA in patients at different stages of hypertension based on a newly developed screening-diagnostic overnight test. This is a prospective study with hypertensive patients (n=265) at stage I (n=100), II (n=88), and III (n=77) of hypertension. A group of 103 patients with essential hypertension without PA was used as controls. PA diagnosis was based on a combined screening-diagnostic overnight test, the Dexamethasone-Captopril-Valsartan Test (DCVT) that evaluates aldosterone secretion after pharmaceutical blockade of angiotensin-II and adrenocorticotropic hormone. DCVT was performed in all participants independently of the basal aldosterone to renin ratio (ARR). The calculated upper normal limits for post-DCVT aldosterone levels [3 ng/dl (85 pmol/l)] and post-DCVT ARR [0.32 ng/dl/μU/ml (9 pmol/IU)] from controls, were applied together to establish PA diagnosis. Using these criteria PA was confirmed in 80 of 265 (30%) hypertensives. The prevalence of PA was: 21% (21/100) in stage I, 33% (29/88) in stage II, and 39% (30/77) in stage III. Serum K+ levels were negatively correlated and urinary K+ was positively correlated in PA patients with post-DCVT ARR (r=–0.349, p <0.01, and r=0.27, p <0.05 respectively). In conclusion, DCVT revealed that PA is a highly prevalent cause of hypertension. DCVT could be employed as a diagnostic tool in all subjects with arterial hypertension of unknown cause.

Download Full-text

Suppression of Aldosterone Secretion After Recumbent Saline Infusion Does Not Exclude Lateralized Primary Aldosteronism

Hypertension ◽

10.1161/hypertensionaha.116.07214 ◽

2016 ◽

Vol 68 (4) ◽

pp. 989-994 ◽

Cited By ~ 12

Author(s):

Erika Cornu ◽

Olivier Steichen ◽

Luis Nogueira-Silva ◽

Elselien Küpers ◽

Jean-Yves Pagny ◽

...

Keyword(s):

Primary Aldosteronism ◽

Saline Infusion ◽

Aldosterone Secretion

Download Full-text

Potassium Channel Mutant KCNJ5 T158A Expression in HAC-15 Cells Increases Aldosterone Synthesis

Endocrinology ◽

10.1210/en.2011-1733 ◽

2012 ◽

Vol 153 (4) ◽

pp. 1774-1782 ◽

Cited By ~ 114

Author(s):

Kenji Oki ◽

Maria W. Plonczynski ◽

Milay Luis Lam ◽

Elise P. Gomez-Sanchez ◽

Celso E. Gomez-Sanchez

Keyword(s):

Potassium Channel ◽

Primary Aldosteronism ◽

Calcium Influx ◽

Fold Increase ◽

Transitional Zone ◽

Selectivity Filter ◽

Adrenal Cortical Carcinoma ◽

Aldosterone Secretion ◽

Familial Hyperaldosteronism ◽

Type 3

Primary aldosteronism is the most common cause of secondary hypertension, most frequently due to an aldosterone-producing adenoma or idiopathic hyperaldosteronism. Somatic mutations of the potassium channel KCNJ5 in the region of the selectivity filter have been found in a significant number of aldosterone-producing adenomas. There are also familial forms of primary aldosteronism, one of which, familial hyperaldosteronism type 3 which to date has been found in one family who presented with a severe abnormality in aldosterone and 18-oxocortisol production and hypertrophy and hyperplasia of the transitional zone of the adrenal cortex. In familial hyperaldosteronism type 3, there is a genomic mutation causing a T158A change of amino acids within the selectivity filter region of the KCNJ5 gene. We are reporting our studies demonstrating that lentiviral-mediated expression of a gene carrying the T158A mutation of the KCNJ5 in the HAC15 adrenal cortical carcinoma cell line causes a 5.3-fold increase in aldosterone secretion in unstimulated HAC15-KCNJ5 cells and that forskolin-stimulated aldosterone secretion was greater than that of angiotensin II. Expression of the mutated KCNJ5 gene decreases plasma membrane polarization, allowing sodium and calcium influx into the cells. The calcium channel antagonist nifedipine and the calmodulin inhibitor W-7 variably inhibited the effect. Overexpression of the mutated KCNJ5 channel resulted in a modest decrease in HAC15 cell proliferation. These studies demonstrate that the T158A mutation of the KCNJ5 gene produces a marked stimulation in aldosterone biosynthesis that is dependent on membrane depolarization and sodium and calcium influx into the HAC15 adrenal cortical carcinoma cells.

Download Full-text

Aldosterone Regulation in Primary Aldosteronism: Differences between Adenoma and Bilateral Hyperplasia

Clinical Science ◽

10.1042/cs051329s ◽

1976 ◽

Vol 51 (s3) ◽

pp. 329s-332s ◽

Cited By ~ 2

Author(s):

F. Mantero ◽

M. Gion ◽

D. Armanini ◽

G. Opocher

Keyword(s):

Primary Aldosteronism ◽

Plasma Renin ◽

Upright Position ◽

Diurnal Variations ◽

Upright Posture ◽

Aldosterone Secretion ◽

Predominant Role ◽

Diurnal Patterns ◽

Different Response ◽

Dependent Mechanism

1. The diurnal patterns of plasma aldosterone, plasma renin activity (PRA), Cortisol and adreno-corticotrophic hormone (ACTH) in the supine and in the upright position have been studied in fourteen patients with primary aldosteronism, five with adenoma and nine with bilateral hyperplasia. Blood samples were drawn at intervals from 6 h to 30 min. 2. Supine patients with an adenoma showed marked diurnal variations of aldosterone, with maximal values at 08.00 hours and minimal values at 18.00 hours and secretory spurts beginning after 02.00 hours. Plasma Cortisol paralleled aldosterone, and ACTH seemed to anticipate aldosterone and Cortisol variations; PRA remained unchanged. In patients with hyperplasia, aldosterone was signicantly lower than in the adenoma group at 08.00 hours, and its decline during the day was less marked; fluctuations rather than secretory episodes were seen. 3. After patients assumed the upright posture, aldosterone remained unchanged or decreased in patients with adenoma, whereas it significantly increased in hyperplasia; PRA remained low, although a slight increment was seen in the latter group. The different response of aldosterone in the two groups was not modified by the administration of propranolol, apparently excluding a renin-dependent mechanism. On the other hand, dexamethasone seemed to affect the response of aldosterone to the upright posture in both groups; in adenoma there was a slight but significant increase, and in hyperplasia the usual rise was partially suppressed. 4. It is concluded that ACTH has a predominant role in regulating aldosterone secretion in primary aldosteronism due to adenoma, whereas its action in bilateral hyperplasia is only permissive.

Download Full-text

Primary aldosteronism associated with a germline variant in CACNA1H

BMJ Case Reports ◽

10.1136/bcr-2018-229031 ◽

2019 ◽

Vol 12 (5) ◽

pp. e229031 ◽

Cited By ~ 1

Author(s):

Kendra Wulczyn ◽

Edward Perez-Reyes ◽

Robert L Nussbaum ◽

Meyeon Park

Keyword(s):

Primary Aldosteronism ◽

De Novo ◽

Missense Variant ◽

Laboratory Evaluation ◽

Loss Of Function ◽

Aldosterone Secretion ◽

Whole Exome ◽

Voltage Dependent ◽

Cell Current ◽

Voltage Sensing Domain

The CACNA1H gene encodes the pore-forming α1 subunit of the T-type voltage-dependent calcium channel CaV3.2, expressed abundantly in the adrenal cortex. Mutations in CACNA1H are associated with various forms of primary aldosteronism (PA), including familial hyperaldosteronism type 4 (FH4). We describe a patient with refractory hypokalaemia and elevated aldosterone secretion independent of renin activity. Despite the absence of overt hypertension in this patient, the laboratory evaluation was consistent with a diagnosis of PA. Whole-exome sequencing revealed a de novo missense variant, R890H, in the voltage sensing domain of CACNA1H. Expression of the variant channel in cells resulted in decreased whole-cell current, consistent with a loss-of-function. We hypothesise this variant is the genetic cause of pathological aldosterone secretion in this patient, and thereby expand the current understanding of the genetic basis of FH4.

Download Full-text