Blockade of T-type voltage-dependent Ca2+ channels by benidipine, a dihydropyridine calcium channel blocker, inhibits aldosterone production in human adrenocortical cell line NCI-H295R

Anti-inflammatory activity of benidipine hydrochloride in LPS-activated mammalian macrophages

Benidipine hydrochloride (BH), a medication frequently used by the hypertension patients, acts as a calcium channel blocker. However, its effects on the macrophages have not been investigated thus far. Our goal was investigating the effect of the benidipine hydrochloride to modulate the J774.2 murine macrophage cells inflammatory activity. Our results suggest that in the absence of a standard stimulating agent (LPS) BH did not stimulate the macrophages to produce pro-inflammatory IL-12p40, TNF-α, GM-CSF and IL-6 cytokines. However, when BH was administrated to the cells in the presence of LPS as stimulating agent, it reduced the production of these pro-inflammatory cytokines. Therefore, it had anti-inflammatory activity. At the clinical setting this study suggests that BH can be utilized as hypertension drug that can suppress the inflammation associated with it.

T- and L-Type Calcium Channels Maintain Calcium Oscillations in the Murine Zona Glomerulosa

BACKGROUND

The zona glomerulosa of the adrenal gland is responsible for the synthesis and release of the mineralocorticoid aldosterone. This steroid hormone regulates salt reabsorption in the kidney and blood pressure. The most important stimuli of aldosterone synthesis are the serum concentrations of angiotensin II and potassium. In response to these stimuli, voltage and intracellular calcium levels in the zona glomerulosa oscillate, providing the signal for aldosterone synthesis. It was proposed that the voltage-gated T-type calcium channel CaV3.2 is necessary for the generation of these oscillations. However, Cacna1h knock-out mice have normal plasma aldosterone levels, suggesting additional calcium entry pathways.

METHODS

We used a combination of calcium imaging, patch clamp, and RNA sequencing to investigate calcium influx pathways in the murine zona glomerulosa.

RESULTS

Cacna1h-/- glomerulosa cells still showed calcium oscillations with similar concentrations as wild-type mice. No calcium channels or transporters were upregulated to compensate for the loss of CaV3.2. The calcium oscillations observed were instead dependent on L-type voltage-gated calcium channels. Furthermore, we found that L-type channels can also partially compensate for an acute inhibition of CaV3.2 in wild-type mice. Only inhibition of both T- and L-type calcium channels abolished the increase of intracellular calcium caused by angiotensin II in wild-type.

CONCLUSIONS

Our study demonstrates that T-type calcium channels are not strictly required to maintain glomerulosa calcium oscillations and aldosterone production. Pharmacological inhibition of T-type channels alone will likely not significantly impact aldosterone production in the long term.

Aldosterone and aldosterone synthase inhibitors in cardiorenal disease

Modulation of the renin-angiotensin-aldosterone system is a foundation of therapy for cardiovascular and kidney diseases. Excess aldosterone plays an important role in cardiovascular disease, contributing to inflammation, fibrosis, and dysfunction in the heart, kidneys, and vasculature through both genomic and mineralocorticoid receptor (MR)-mediated as well as nongenomic mechanisms. MR antagonists have been a key therapy for attenuating the pathologic effects of aldosterone but are associated with some side effects and may not always adequately attenuate the nongenomic effects of aldosterone. Aldosterone is primarily synthesized by the CYP11B2 aldosterone synthase enzyme, which is very similar in structure to other enzymes involved in steroid biosynthesis including CYP11B1, a key enzyme involved in glucocorticoid production. Lack of specificity for CYP11B2, off-target effects on the hypothalamic-pituitary-adrenal axis, and counterproductive increased levels of bioactive steroid intermediates such as 11-deoxycorticosterone have posed challenges in the development of early aldosterone synthase inhibitors such as osilodrostat. In early-phase clinical trials, newer aldosterone synthase inhibitors demonstrated promise in lowering blood pressure in patients with treatment-resistant and uncontrolled hypertension. It is therefore plausible that these agents offer protection in other disease states including heart failure or chronic kidney disease. Further clinical evaluation will be needed to clarify the role of aldosterone synthase inhibitors, a promising class of agents that represent a potentially major therapeutic advance.

CaV3.2 (CACNA1H) in Primary Aldosteronism

Aldosterone is a steroid hormone produced in the zona glomerulosa (ZG) of the adrenal cortex. The most prominent function of aldosterone is the control of electrolyte homeostasis and blood pressure via the kidneys. The primary factors regulating aldosterone synthesis are the serum concentrations of angiotensin II and potassium. The T-type voltage-gated calcium channel Ca_V3.2 (encoded by CACNA1H) is an important component of electrical as well as intracellular calcium oscillations, which govern aldosterone production in the ZG. Excessive aldosterone production that is (partially) uncoupled from physiological stimuli leads to primary aldosteronism, the most common cause of secondary hypertension. Germline gain-of-function mutations in CACNA1H were identified in familial hyperaldosteronism, whereas somatic mutations are a rare cause of aldosterone-producing adenomas. In this review, we summarize these findings, put them in perspective, and highlight missing knowledge.

T-type calcium channels blockers inhibit HSV-2 infection at the late stage of genome replication

Herpes simplex virus type 2 (HSV-2) is a highly contagious sexually transmitted virus. The increasing emergence of drug-resistant viral strains has highlighted the crucial need for the development of new anti-HSV-2 drugs with different mechanisms. Ion channels that govern a wide range of cellular functions represent attractive targets for viral manipulation. Here, we tried to identify novel compounds to suppress HSV-2 infection in vitro by screening a small library with ion channels modulators. We found that several T-type calcium channel blockers including benidipine, lercanidipine, lomerizine and mibefradil inhibited HSV-2 infection, while L-type calcium channel blockers nifedipine and nitrendipine showed no significant effect on HSV-2 infection. Furthermore, we found that benidipine exerted the antiviral effect by suppressing the expression of viral genes in the late stage of viral infection. In conclusion, our study suggested that T-type calcium channel blockers, which are clinically wide used, could effectively inhibit HSV-2 infection. These findings could shed light on the mechanism and pharmacological study for HSV-2 infection in the future.

Amlodipine Compared with Benidipine in the Management of Hypertension: A Systematic Review and Meta-Analysis

INTRODUCTION

Benidipine and amlodipine are two well-known drugs used in hypertensive patients with chronic kidney disease (CKD).

AIM

In this systematic review we aimed to compare benidipine and amlodipine in terms of efficacy in the management of hypertensive patients.

METHODS

We searched PubMed, Cochrane CENTRAL, SCOPUS and Web of Science for relevant clinical trials and excluded observational studies. Quality appraisal was evaluated according to GRADE and we assessed the risk of bias using the Cochrane's risk of bias tool. We included the following outcomes: Systolic blood pressure, diastolic blood pressure, heart rate, estimated glomerular filtration rate (eGFR), and urinary albumin/creatinine ratio. Data were pooled as mean differences (MD) with relative 95% confidence intervals (CI).

RESULTS

Eight studies were eligible for our meta-analysis. We found no significant difference between both drugs regarding systolic (MD = - 0.21 [- 1.48, 1.89], (P = 0.81) and diastolic (MD = 0.01[- 0.51, 0.53], (P = 0.97)) blood pressure measurements. The overall heart rate did not differ as well (MD = - 0.03 [- 1.63, 1.57], (P = 0.97)). We found that benidipine was statistically better than amlodipine in terms of eGFR (MD = 1.07 [0.43, 1.71], (P = 0.001)), and urinary albumin/creatinine ratio (MD = - 43.41 [- 53.53, - 33.29], (P < 0.00001)).

CONCLUSIONS

Finally we conclude that benidipine seems to show more positive and promising results in the management of hypertensive patients with chronic kidney disease.

L- and T-type calcium channels control aldosterone production from human adrenals

Aldosterone, which plays a key role in the regulation of blood pressure, is produced by zona glomerulosa (ZG) cells of the adrenal cortex. Exaggerated overproduction of aldosterone from ZG cells causes primary hyperaldosteronism. In ZG cells, calcium entry through voltage-gated calcium channels plays a central role in the regulation of aldosterone secretion. Previous studies in animal adrenals and human adrenal adrenocortical cell lines suggest that the T-type but not the L-type calcium channel activity drives aldosterone production. However, recent clinical studies show that somatic mutations in L-type calcium channels are the second most prevalent cause of aldosterone-producing adenoma. Our objective was to define the roles of T and L-type calcium channels in regulating aldosterone secretion from human adrenals. We find that human adrenal ZG cells mainly express T-type CaV3.2/3.3 and L-type CaV1.2/1.3 calcium channels. TTA-P2, a specific inhibitor of T-type calcium channel subtypes, reduced basal aldosterone secretion from acutely prepared slices of human adrenals. Surprisingly, nifedipine, the prototypic inhibitor of L-type calcium channels, also decreased basal aldosterone secretion, suggesting that L-type calcium channels are active under basal conditions. In addition, TTA-P2 or nifedipine also inhibited aldosterone secretion stimulated by angiotensin II- or elevations in extracellular K+. Remarkably, blockade of either L- or T-type calcium channels inhibits basal and stimulated aldosterone production to a similar extent. Low concentrations of TTA-P2 and nifedipine showed additive inhibitory effect on aldosterone secretion. We conclude that T- and L-type calcium channels play equally important roles in controlling aldosterone production from human adrenals.

Calcium Ion Channels: Roles in Infection and Sepsis Mechanisms of Calcium Channel Blocker Benefits in Immunocompromised Patients at Risk for Infection

Immunosuppression may occur for a number of reasons related to an individual's frailty, debility, disease or from therapeutic iatrogenic intervention or misadventure. A large percentage of morbidity and mortality in immunodeficient populations is related to an inadequate response to infectious agents with slow response to antibiotics, enhancements of antibiotic resistance in populations, and markedly increased prevalence of acute inflammatory response, septic and infection related death. Given known relationships between intracellular calcium ion concentrations and cytotoxicity and cellular death, we looked at currently available data linking blockade of calcium ion channels and potential decrease in expression of sepsis among immunosuppressed patients. Notable are relationships between calcium, calcium channel, vitamin D mechanisms associated with sepsis and demonstration of antibiotic-resistant pathogens that may utilize channels sensitive to calcium channel blocker. We note that sepsis shock syndrome represents loss of regulation of inflammatory response to infection and that vitamin D, parathyroid hormone, fibroblast growth factor, and klotho interact with sepsis defense mechanisms in which movement of calcium and phosphorus are part of the process. Given these observations we consider that further investigation of the effect of relatively inexpensive calcium channel blockade agents of infections in immunosuppressed populations might be worthwhile.

Effect of Angiotensin-Converting Enzyme Inhibitor/Calcium Antagonist Combination Therapy on Renal Function in Hypertensive Patients With Chronic Kidney Disease: Chikushi Anti-Hypertension Trial - Benidipine and Perindopril

Background

Appropriate blood pressure control suppresses progression of chronic kidney disease (CKD). If an angiotensin-converting enzyme (ACE) inhibitor is ineffective, adding a calcium antagonist is recommended. We compared the long-term effect of two ACE inhibitor/calcium antagonist combinations on renal function in hypertensive patients with CKD.

Methods

Patients who failed to achieve the target blood pressure (systolic/diastolic: < 130/80 mm Hg) with perindopril monotherapy were randomized to either combined therapy with perindopril and the L-type calcium antagonist amlodipine (group A) or perindopril and the T/L type calcium antagonist benidipine (group B). The primary endpoint was the change of the estimated glomerular filtration rate (eGFR) after 2 years. Eligible patients had a systolic pressure ≥ 130 mm Hg and/or diastolic pressure ≥ 80 mm Hg and CKD (urine protein (+) or higher, eGFR < 60 min/mL/1.73 m²).

Results

After excluding 38 patients achieving the target blood pressure with perindopril monotherapy, 121 patients were analyzed (62 in group A and 59 in group B). Blood pressure decreased significantly in both groups, but there was no significant change of the eGFR. However, among patients with diabetes, eGFR unchanged in group B (n = 37, 59.1 ± 15.1 vs. 61.2 ± 27.9, P = 0.273), whereas decreased significantly in group A (n = 31, 57.3 ± 16.0 vs. 53.7 ± 16.7, P = 0.005).

Conclusions

In hypertensive patients with diabetic nephropathy, combined therapy with an ACE inhibitor and T/L type calcium antagonist may prevent deterioration of renal function more effectively than an ACE inhibitor/L type calcium antagonist combination.

High glucose stimulates expression of aldosterone synthase (CYP11B2) and secretion of aldosterone in human adrenal cells

Aldosterone synthase is the key rate‐limiting enzyme in adrenal aldosterone production, and induction of its gene (CYP11B2) results in the progression of hypertension. As hypertension is a frequent complication among patients with diabetes, we set out to elucidate the link between diabetes mellitus and hypertension. We examined the effects of high glucose on CYP11B2 expression and aldosterone production using human adrenal H295R cells and a stable H295R cell line expressing a CYP11B2 5′‐flanking region/luciferase cDNA chimeric construct. d‐glucose (d‐glu), but not its enantiomer l‐glucose, dose dependently induced CYP11B2 transcription and mRNA expression. A high concentration (450 mg·dL⁻¹) of d‐glu time dependently induced CYP11B2 transcription and mRNA expression. Moreover, high glucose stimulated secretion of aldosterone into the media. Transient transfection studies using deletion mutants/nerve growth factor‐induced clone B (NGFIB) response element 1 (NBRE‐1) point mutant of CYP11B2 5′‐flanking region revealed that the NBRE‐1 element, known to be activated by transcription factors NGFIB and NURR1, was responsible for the high glucose‐mediated effect. High glucose also induced the mRNA expression of these transcription factors, especially that of NURR1, but NURR1 knockdown using its siRNA did not affect high glucose‐induced CYP11B2 mRNA expression. Taken together, it is speculated that high glucose may induce CYP11B2 transcription via the NBRE‐1 element in its 5′‐flanking region, resulting in the increase in aldosterone production although high glucose‐induced NURR1 is not directly involved in the effect. Additionally, glucose metabolism and calcium channels were found to be involved in the high glucose effect. Our observations suggest one possible explanation for the high incidence of hypertension in patients with diabetes.

CACNA1H(M1549V) Mutant Calcium Channel Causes Autonomous Aldosterone Production in HAC15 Cells and Is Inhibited by Mibefradil

We recently demonstrated that a recurrent gain-of-function mutation in a T-type calcium channel, CACNA1H(M1549V), causes a novel Mendelian disorder featuring early-onset primary aldosteronism and hypertension. This variant was found independently in five families. CACNA1H(M1549V) leads to impaired channel inactivation and activation at more hyperpolarized potentials, inferred to cause increased calcium entry. We here aimed to study the effect of this variant on aldosterone production. We heterologously expressed empty vector, CACNA1H(WT) and CACNA1H(M1549V) in the aldosterone-producing adrenocortical cancer cell line H295R and its subclone HAC15. Transfection rates, expression levels, and subcellular distribution of the channel were similar between CACNA1H(WT) and CACNA1H(M1549V). We measured aldosterone production by an ELISA and CYP11B2 (aldosterone synthase) expression by real-time PCR. In unstimulated cells, transfection of CACNA1H(WT) led to a 2-fold increase in aldosterone levels compared with vector-transfected cells. Expression of CACNA1H(M1549V) caused a 7-fold increase in aldosterone levels. Treatment with angiotensin II or increased extracellular potassium levels further stimulated aldosterone production in both CACNA1H(WT)- and CACNA1H(M1549V)-transfected cells. Similar results were obtained for CYP11B2 expression. Inhibition of CACNA1H channels with the T-type calcium channel blocker Mibefradil completely abrogated the effects of CACNA1H(WT) and CACNA1H(M1549V) on CYP11B2 expression. These results directly link CACNA1H(M1549V) to increased aldosterone production. They suggest that calcium channel blockers may be beneficial in the treatment of a subset of patients with primary aldosteronism. Such blockers could target CACNA1H or both CACNA1H and the L-type calcium channel CACNA1D that is also expressed in the adrenal gland and mutated in patients with primary aldosteronism.

Two-pore domain potassium channels in the adrenal cortex

The physiological control of steroid hormone secretion from the adrenal cortex depends on the function of potassium channels. The "two-pore domain K(+) channels" (K2P) TWIK-related acid sensitive K(+) channel 1 (TASK1), TASK3, and TWIK-related K(+) channel 1 (TREK1) are strongly expressed in adrenocortical cells. They confer a background K(+) conductance to these cells which is important for the K(+) sensitivity as well as for angiotensin II and adrenocorticotropic hormone-dependent stimulation of aldosterone and cortisol synthesis. Mice with single deletions of the Task1 or Task3 gene as well as Task1/Task3 double knockout mice display partially autonomous aldosterone synthesis. It appears that TASK1 and TASK3 serve different functions: TASK1 affects cell differentiation and prevents expression of aldosterone synthase in the zona fasciculata, while TASK3 controls aldosterone secretion in glomerulosa cells. TREK1 is involved in the regulation of cortisol secretion in fasciculata cells. These data suggest that a disturbed function of K2P channels could contribute to adrenocortical pathologies in humans.

Regulation of aldosterone synthesis and secretion

Aldosterone is a steroid hormone synthesized in and secreted from the outer layer of the adrenal cortex, the zona glomerulosa. Aldosterone is responsible for regulating sodium homeostasis, thereby helping to control blood volume and blood pressure. Insufficient aldosterone secretion can lead to hypotension and circulatory shock, particularly in infancy. On the other hand, excessive aldosterone levels, or those too high for sodium status, can cause hypertension and exacerbate the effects of high blood pressure on multiple organs, contributing to renal disease, stroke, visual loss, and congestive heart failure. Aldosterone is also thought to directly induce end-organ damage, including in the kidneys and heart. Because of the significance of aldosterone to the physiology and pathophysiology of the cardiovascular system, it is important to understand the regulation of its biosynthesis and secretion from the adrenal cortex. Herein, the mechanisms regulating aldosterone production in zona glomerulosa cells are discussed, with a particular emphasis on signaling pathways involved in the secretory response to the main controllers of aldosterone production, the renin-angiotensin II system, serum potassium levels and adrenocorticotrophic hormone. The signaling pathways involved include phospholipase C-mediated phosphoinositide hydrolysis, inositol 1,4,5-trisphosphate, cytosolic calcium levels, calcium influx pathways, calcium/calmodulin-dependent protein kinases, diacylglycerol, protein kinases C and D, 12-hydroxyeicostetraenoic acid, phospholipase D, mitogen-activated protein kinase pathways, tyrosine kinases, adenylate cyclase, and cAMP-dependent protein kinase. A complete understanding of the signaling events regulating aldosterone biosynthesis may allow the identification of novel targets for therapeutic interventions in hypertension, primary aldosteronism, congestive heart failure, renal disease, and other cardiovascular disorders.

Renal microcirculation and calcium channel subtypes

It has recently been reported that voltage-dependent Ca channel subtypes, e.g., L-, T-, N-, and P/Q-type, are expressed in renal arterioles and renal tubules, and the inhibition of these channels exerts various effects on renal microcirculation. For example, selective blockade of L-type Ca channels with nifedipine preferentially dilates the afferent arteriole and potentially induces glomerular hypertension. On the other hand, recently developed Ca channel blockers (CCBs) such as mibefradil and efonidipine block both T-type and L-type Ca channels and consequently dilate both afferent and efferent arterioles, leading to lowering of intraglomerular pressure. Interestingly, aldosterone has recently been recognized as a factor exacerbating renal diseases, and its secretion from adrenal gland is mediated by T-type Ca channels. Furthermore, T-type CCBs were shown to ameliorate renal dysfunction by suppressing inflammatory processes and renin secretion. On the basis of histological evaluations, N-type Ca channels are present in peripheral nerve terminals innervating both afferent and efferent arterioles. Further, it was suggested that N-type CCBs such as cilnidipine suppress renal arteriolar constriction induced by enhanced sympathetic nerve activity, thereby lowering intraglomerular pressure. Taken together, various Ca channel subtypes are present in the kidney and blockade of selective channels with distinct CCBs exerts diverse effects on renal microcirculation. Inhibition of T-type and N-type Ca channels with CCBs is anticipated to exert pleiotropic effects that would retard the progression of chronic kidney disease through modulation of renal hemodynamic and non-hemodynamic processes.

Effects of the T/L-type calcium channel blocker benidipine on albuminuria and plasma aldosterone concentration. A pilot study involving switching from L-type calcium channel blockers to benidipine

Albuminuria and a high plasma aldosterone concentration (PAC) are prognosis factors predicting a poor outcome for cardiovascular disease. We examined here the effects of benidipine, a T/L-type calcium channel blocker (CCB), on albuminuria and PAC.Thirty-one patients with essential hypertension who received an L-type CCB and achieved the target blood pressure (BP) indicated by the Treatment Guidelines of the Japan Society of Hypertension (JSH2009) were investigated. The Ltype CCB under treatment was switched to benidipine at a dose in which equivalent BP reduction was expected. BP and estimated glomerular filtration rate at 6 months after switching to benidipine were not significantly different from those at baseline. The urinary-albumin-creatinine ratio (UACR) decreased significantly by 36.9% (P = 0.001). No significant change was observed in plasma renin activity (P = 0.063). The PAC of all patients decreased significantly by 11.8% (P = 0.002). When analyzed by daily doses of benidipine, the PAC appeared to have decreased in patients who received 4 mg per day of benidipine (n = 14), although statistical significance was not reached (P = 0.096). The PAC in patients who received 8 mg per day of benidipine (n =17) was significantly reduced by 13.2% (P = 0.017).In hypertensive patients whose BP is controlled by L-type CCB, switching to the T/L-type CCB benidipine maintained BP control and reduced UACR. In addition, the high dose of benidipine reduced the PAC independent of BP control. These results suggest the T/L-type CCB benidipine may contribute to cardio-renal protection in addition to lowering BP.

Dissecting the molecular pathways of primary aldosteronism

The great majority of the cases clinically diagnosed as primary aldosteronism (PA) have been caused by aldosterone-producing adenoma (APA) or idiopathic hyperaldosteronism (IHA). The differential diagnosis of both subtypes of PA is important due to the different therapeutic modes but clinically it is sometimes difficult. It is also important to understand the morphological features of these two subtypes with special emphasis upon differences of the status for aldosterone biosynthesis. In the last decade, molecular mechanisms of PA including the aberrant expression of G-protein coupled receptors (GPCRs), key regulators of the intracellular calcium signaling pathway and somatic mutations of ion channels, have been revealed and our understanding of the molecular pathways involved in excessive aldosterone production has been markedly advanced. In addition, newly developed monoclonal antibodies specific to the isoform of adrenal steroidogenic enzymes have demonstrated the novel profiles of adrenal steroidogenesis in PA. These novel findings indicate that the molecular mechanisms on the onset and pathophysiology of PA are more complicated than previously considered and further clarification of clinical relevance of these findings is required at this juncture.

Voltage-gated calcium channels in the human adrenal and primary aldosteronism

Calcium channel blockers can efficiently be used in the treatment of primary aldosteronism (PA) related hypertension, but details on the localization of calcium channel (CC) in the human adrenal and its disorders, including PA, have remained unclear. Therefore, in this study we analyzed the known α subunits of L-, N- and T-type CCs in 74 adrenocortical aldosterone-producing adenomas (APA) and 16 cortisol-producing adenomas (CPA) using quantitative RT-PCR (qPCR). We also examined the status of L-(CaV1.2, CaV1.3), N-(CaV2.2) and T-(CaV3.2) CC subunits in five non-pathological adrenals (NA), five idiopathic hyperaldosteronism (IHA) cases, and 50 APA using immunohistochemistry. After qPCR evaluation, only CaV1.2, CaV1.3, CaV2.2, and CaV3.2 mRNA levels could be detected in APA and CPA. Among those, only CaV3.2 mRNA levels were significantly correlated with plasma aldosterone levels (P=0.0031), CYP11B2 expression levels (P<0.0001) and the presence of KCNJ5 mutations (P=0.0019) in APA. The immunolocalization of CCs in NA and IHA was detected in the zona glomerulosa (ZG), with a predominance of CaV3.2 in APA. These findings suggest that different types of CC can be involved in calcium-related aldosterone biosynthesis.

Diastrophic dysplasia sulfate transporter (SLC26A2) is expressed in the adrenal cortex and regulates aldosterone secretion

Elucidation of the molecular mechanisms leading to autonomous aldosterone secretion is a prerequisite to define potential targets and biomarkers in the context of primary aldosteronism. After a genome-wide association study with subjects from the population-based Cooperative Health Research in the Region of Augsburg F4 survey, we observed a highly significant association (P=6.78×10(-11)) between the aldosterone to renin ratio and a locus at 5q32. Hypothesizing that this locus may contain genes of relevance for the pathogenesis of primary aldosteronism, we investigated solute carrier family 26 member 2 (SLC26A2), a protein with known transport activity for sulfate and other cations. Within murine tissues, adrenal glands showed the highest expression levels for SLC26A2, which was significantly downregulated on in vivo stimulation with angiotensin II and potassium. SLC26A2 expression was found to be significantly lower in aldosterone-producing adenomas in comparison with normal adrenal glands. In adrenocortical NCI-H295R cells, specific knockdown of SLC26A2 resulted in a highly significant increase in aldosterone secretion. Concomitantly, expression of steroidogenic enzymes, as well as upstream effectors including transcription factors such as NR4A1, CAMK1, and intracellular Ca(2+) content, was upregulated in knockdown cells. To substantiate further these findings in an SLC26A2 mutant mouse model, aldosterone output proved to be increased in a sex-specific manner. In summary, these findings point toward a possible effect of SLC26A2 in the regulation of aldosterone secretion potentially involved in the pathogenesis of primary aldosteronism.

NCI-H295R, a human adrenal cortex-derived cell line, expresses purinergic receptors linked to Ca²⁺-mobilization/influx and cortisol secretion

Purinergic receptor expression and involvement in steroidogenesis were examined in NCI-H295R (H295R), a human adrenal cortex cell line which expresses all the key enzymes necessary for steroidogenesis. mRNA/protein for multiple P1 (A_2A and A_2B), P2X (P2X₅ and P2X₇), and P2Y (P2Y₁, P2Y₂, P2Y₆, P2Y₁₂, P2Y₁₃, and P2Y₁₄) purinergic receptors were detected in H295R. 2MeS-ATP (10–1000 µM), a P2Y₁ agonist, induced glucocorticoid (GC) secretion in a dose-dependent manner, while other extracellular purine/pyrimidine agonists (1–1000 µM) had no distinct effect on GC secretion. Extracellular purines, even non-steroidogenic ones, induced Ca²⁺-mobilization in the cells, independently of the extracellular Ca²⁺ concentration. Increases in intracellular Ca²⁺ concentration induced by extracellular purine agonists were transient, except when induced by ATP or 2MeS-ATP. Angiotensin II (AngII: 100 nM) and dibutyryl-cyclic AMP (db-cAMP: 500 µM) induced both GC secretion and Ca²⁺-mobilization in the presence of extracellular Ca²⁺ (1.2 mM). GC secretion by AngII was reduced by nifedipine (10–100 µM); whereas the Ca²⁺ channel blocker did not inhibit GC secretion by 2MeS-ATP. Thapsigargin followed by extracellular Ca²⁺ exposure induced Ca²⁺-influx in H295R, and the cells expressed mRNA/protein of the component molecules for store-operated calcium entry (SOCE): transient receptor C (TRPC) channels, calcium release-activated calcium channel protein 1 (Orai-1), and the stromal interaction molecule 1 (STIM1). In P2Y₁-knockdown, 2MeS-ATP-induced GC secretion was significantly inhibited. These results suggest that H295R expresses a functional P2Y₁ purinergic receptor for intracellular Ca²⁺-mobilization, and that P2Y₁ is linked to SOCE-activation, leading to Ca²⁺-influx which might be necessary for glucocorticoid secretion.

Combination therapy for hypertension in patients with CKD: a subanalysis of the Combination Therapy of Hypertension to Prevent Cardiovascular Events trial

The Combination Therapy of Hypertension to Prevent Cardiovascular Events (COPE) trial was a multicenter, randomized, three-arm comparative study (N=3293) undertaken to determine the optimal combination therapy, based on the occurrence of cardiovascular events in patients treated with an angiotensin II receptor blocker (ARB), a β-blocker (BB) or a thiazide diuretic (TD) in addition to the calcium antagonist benidipine as baseline medication. This subanalysis was conducted to compare the efficacy of three combination therapies in a subset of 834 patients with chronic kidney disease (CKD) (287 patients treated with benidpine-ARB, 283 patients treated with benidipine-BB and 264 patients treated with benidipine-TD). The incidence of composite cardiovascular events as the primary end point did not differ among these three groups. The incidence of hard end points and cerebrovascular events among these groups did not differ either, although the incidence among all patients in the COPE trial was lower in the benidipine-TD group than in the benidipine-BB group. The incidence of new-onset diabetes mellitus was higher in the benidipine-TD group than in the benidipine-ARB group among patients with CKD. The estimated glomerular filtration rate (eGFR) was maintained even after 12 months of treatment in patients with a baseline eGFR <60 ml min(-1) per 1.73 m(2) regardless of the treatment group, although the eGFR decreased over time in all patients in the three groups. In conclusion, in patients with CKD, all of the tested combination therapies demonstrated comparable efficacy in terms of prevention of cardiovascular events as well as maintenance of eGFR.

Regulation of aldosterone secretion: from physiology to disease

Arterial hypertension is a major cardiovascular risk factor that affects between 10 and 40% of the population in industrialized countries. Primary aldosteronism (PA) is the most common form of secondary hypertension with an estimated prevalence of around 10% in referral centers and 4% in a primary care setting. Despite its high prevalence until recently, the underlying genetic and molecular basis of this common disease had remained largely obscure. Over the past decade, a number of insights have been achieved that have relied on in vitro cellular systems, wild-type and genetically modified in vivo models, as well as clinical studies in well-characterized patient populations. This progress has been made possible by a number of independent technical developments including that of specific hormone assays that allow measurement in small sample volumes as well as genetic techniques that enable high-throughput sequencing of a large number of samples. Furthermore, animal models have provided important insights into the physiology of aldosterone regulation that have served as a starting point for investigation of mechanisms involved in autonomous aldosterone secretion. Finally, national and international networks that have built up registries and biobanks have been instrumental in fostering translational research endeavors in PA. Therefore, it is to be expected that in the near future, further pathophysiological mechanisms that result in autonomous aldosterone secretion will be unraveled.

Benidipine protects kidney through inhibiting ROCK1 activity and reducing the epithelium-mesenchymal transdifferentiation in type 1 diabetic rats

We investigated the protective effect of benidipine, by testing the changes of the activity of Rho kinase and transdifferentiation of renal tubular epithelium cells in vivo. Wistar rats were randomly divided into two groups: normal (N) and diabetes. STZ were used to make the rats type 1 diabetic and were randomly assigned as diabetes without treatment (D), diabetes treated with benidipine (B), and diabetes treated with fasudil (F) and treated for 3 months. Immunohistochemistry and western blotting were for protein expressions of ROCK1, α-SMA, and E-cadherin and real-time PCR for the mRNA quantification of ROCK1. Compared with N group, D group had significant proliferation of glomerular mesangial matrix, increased cell number, thickened basement membrane, widely infiltrated by inflammatory cells and fibrosis in the renal interstitial, and dilated tubular. Those presentations in F and B groups were milder. Compared with N group, D group showed elevated MYPT1 phosphorylation, increased expression of ROCK1, α-SMA protein, and ROCK1 mRNA and decreased expression of E-cadherin protein. B group showed attenuated MYPT1 phosphorylation, decreased ROCK1, α-SMA protein, and ROCK1 mRNA expression and increased expression of E-cadherin protein. In conclusion, benidipine reduces the epithelium-mesenchymal transdifferentiation and renal interstitial fibrosis in diabetic kidney by inhibiting ROCK1 activity.

Key advances in antihypertensive treatment

Although various effective treatments for hypertension are available, novel therapies to reduce elevated blood pressure, improve blood-pressure control, treat resistant hypertension, and reduce the associated cardiovascular risk factors are still required. A novel angiotensin-receptor blocker (ARB) was approved in 2011, and additional compounds are in development or being tested in clinical trials. Several of these agents have innovative mechanisms of action (an aldosterone synthase inhibitor, a natriuretic peptide agonist, a soluble epoxide hydrolase inhibitor, and an angiotensin II type 2 receptor agonist) or dual activity (a combined ARB and neutral endopeptidase inhibitor, an ARB and endothelin receptor A blocker, and an endothelin-converting enzyme and neutral endopeptidase inhibitor). In addition, several novel fixed-dose combinations of existing antihypertensive agents were approved in 2010-2011, including aliskiren double and triple combinations, and an olmesartan triple combination. Upcoming fixed-dose combinations are expected to introduce calcium-channel blockers other than amlodipine and diuretics other than hydrochlorothiazide. Finally, device-based approaches to the treatment of resistant hypertension, such as renal denervation and baroreceptor activation therapy, have shown promising results in clinical trials. However, technical improvements in the implantation procedure and devices used for baroreceptor activation therapy are required to address procedural safety concerns.

Suppression of aldosterone synthesis and secretion by ca(2+) channel antagonists

Aldosterone, a specific mineralocorticoid receptor (MR) agonist and a key player in the development of hypertension, is synthesized as a final product of renin-angiotensin-aldosterone system. Hypertension can be generally treated by negating the effects of angiotensin II through the use of angiotensin-converting enzyme inhibitors (ACE-Is) or angiotensin II type 1 receptor antagonists (ARBs). However, the efficacy of angiotensin II blockade by such drugs is sometimes diminished by the so-called "aldosterone breakthrough" effect, by which ACE-Is or ARBs (renin-angiotensin system (RAS) inhibitors) gradually lose their effectiveness against hypertension due to the overproduction of aldosterone, known as primary aldosteronism. Although MR antagonists are used to antagonize the effects of aldosterone, these drugs may, however, give rise to life-threatening adverse actions, such as hyperkalemia, particularly when used in conjunction with RAS inhibitors. Recently, several groups have reported that some dihydropyridine Ca(2+) channel blockers (CCBs) have inhibitory actions on aldosterone production in in vitro and in the clinical setting. Therefore, the use of such dihydropyridine CCBs to treat aldosterone-related hypertension may prove beneficial to circumvent such therapeutic problems. In this paper, we discuss the mechanism of action of CCBs on aldosterone production and clinical perspectives for CCB use to inhibit MR activity in hypertensive patients.

Benidipine reduces ischemia reperfusion-induced systemic oxidative stress through suppression of aldosterone production in mice

Aldosterone is implicated in the pathogenesis of several cardiovascular diseases, including ischemia reperfusion (I/R) and myocardial infarction, and also causes oxidative stress and inflammation in cardiovascular systems. Benidipine, a long-acting T- and L-type calcium channel blocker, reduces infarct size following myocardial I/R in rabbits. Benidipine also inhibits the production of aldosterone in vitro. However, the precise mechanism of this phenomenon in vivo remains unknown. We therefore evaluated whether benedipine has a beneficial role through the regulation of oxidative stress in myocardial I/R. C57BL/6J mice were subjected to 30 min of left ascending coronary I/R. Benidipine was administered orally at 3 mg kg(-1) daily for 3 weeks without any changes in hemodynamic variables. Benidipine significantly reduced infarction size (13.4±2.5%) compared with controls (25.5±3.6%). Urinary 8-hydroxy-2' deoxyguanosine (8-OHdG), a marker of oxidative DNA damage, increased significantly after I/R. I/R induced increases in 8-OHdG were significantly lower with benidipine. Local myocardial 8-OHdG was also elevated in I/R, but this augmentation was significantly suppressed with benidipine. The plasma aldosterone concentration (PAC) significantly increased 2 days after I/R and remained elevated at least 7 days after I/R. Treatment with benidipine significantly decreased I/R-induced elevation of the PAC. I/R-induced markers of fibrosis in hearts also reduced in benidipine. These results suggest that the administration of benidipine reduces myocardial infarct size as well as systemic oxidative stress after I/R. These phenomena are partially linked to reduced plasma aldosterone levels.

Design, synthesis, and pharmacological evaluation of haloperidol derivatives as novel potent calcium channel blockers with vasodilator activity

Several haloperidol derivatives with a piperidine scaffold that was decorated at the nitrogen atom with different alkyl, benzyl, or substituted benzyl moieties were synthesized at our laboratory to establish a library of compounds with vasodilator activity. Compounds were screened for vasodilatory activity on isolated thoracic aorta rings from rats, and their quantitative structure-activity relationships (QSAR) were examined. Based on the result of QSAR, N-4-tert-butyl benzyl haloperidol chloride (16c) was synthesized and showed the most potent vasodilatory activity of all designed compounds. 16c dose-dependently inhibited the contraction caused by the influx of extracellular Ca(2+) in isolated thoracic aorta rings from rats. It concentration-dependently attenuated the calcium channel current and extracellular Ca(2+) influx, without affecting the intracellular Ca(2+) mobilization, in vascular smooth muscle cells from rats. 16c, possessing the N-4-tert-butyl benzyl piperidine structure, as a novel calcium antagonist, may be effective as a calcium channel blocker in cardiovascular disease.

Therapeutic perspectives in hypertension: novel means for renin-angiotensin-aldosterone system modulation and emerging device-based approaches

The conventional antihypertensive therapies including renin–angiotensin–aldosterone system antagonists (converting enzyme inhibitors, receptor blockers, renin inhibitors, and mineralocorticoid receptor blockers), diuretics, β-blockers, and calcium channel blockers are variably successful in achieving the challenging target blood pressure values in hypertensive patients. Difficult to treat hypertension is still a commonly observed problem world-wide. A number of drugs are considered to be used as novel therapies for hypertension. Renalase supplementation, vasopeptidase inhibitors, endothelin antagonists, and especially aldosterone antagonists (aldosterone synthase inhibitors and novel selective mineralocorticoid receptor blockers) are considered an option in resistant hypertension. In addition, the aldosterone antagonists as well as (pro)renin receptor blockers or AT₂ receptor agonists might attenuate end-organ damage. This array of medications has now been complemented by a number of new approaches of non-pharmacological strategies including vaccination, genomic interference, controlled breathing, baroreflex activation, and probably most successfully renal denervation techniques. However, the progress on innovative therapies seems to be slow and the problem of resistant hypertension and proper blood pressure control appears to be still persisting. Therefore the regimens of currently available drugs are being fine-tuned, resulting in the establishment of several novel fixed-dose combinations including triple combinations with the aim to facilitate proper blood pressure control. It remains an exciting question which approach will confer the best blood pressure control and risk reduction in this tricky disease.

Mechanism underlying the block of human Cav3.2 T-type Ca2+ channels by benidipine, a dihydropyridine Ca2+ channel blocker

AIMS

Benidipine, a dihydropyridine Ca(2+) channel blocker, has been reported to block T-type Ca(2+) channels; however, the mechanism underlying this effect was unclear. In this study, we characterized the mechanism responsible for this blocking activity. Furthermore, the blocking activity was compared between two enantiomers of benidipine, (S, S)- and (R, R)-benidipine.

MAIN METHODS

Human Ca(v)3.2 (hCa(v)3.2) T-type Ca(2+) channels stably expressed in the human embryonic kidney cell line, HEK-293, were studied in whole-cell patch-clamp recordings and Ca(2+) mobilization assay.

KEY FINDINGS

In whole-cell patch-clamp recordings, benidipine blocked hCa(v)3.2 T-type Ca(2+) currents elicited by depolarization to a comparable extent as efonidipine. The block was dependent on stimulation frequency and holding potential, but not test potential. Benidipine significantly shifted the steady-state inactivation curve to the hyperpolarizing direction, but had no effect on the activation curve. Benidipine prolonged the recovery from inactivation of hCa(v)3.2 T-type Ca(2+) channels without any effect on the kinetics of activation, inactivation, or deactivation. In the Ca(2+) mobilization assay, benidipine was more potent than efonidipine in blocking Ca(2+) influx through hCa(v)3.2 T-type Ca(2+) channels. (S, S)-Benidipine was more potent than (R, R)-benidipine in blocking hCa(v)3.2 T-type Ca(2+) currents, but there was no difference in blocking the Ca(2+) influx.

SIGNIFICANCE

We have characterized the blocking activity of benidipine against hCa(v)3.2 Ca(2+) channels and revealed the difference between the two enantiomers of benidipine. The blocking action of benidipine could be mediated by stabilizing hCa(v)3.2 Ca(2+) channels in an inactivated state.

Primary aldosteronism, diagnosis and treatment in Japan

Primary aldosteronism (PA) has been recognized as a common cause of secondary hypertension and accounts for approximately 5-15% of the hypertensive population in Japan. Screening for PA should therefore be carried out in all hypertensive patients as we have shown the estimated prevalence of PA is 13.6% in pre-hypertensive subjects and 9.1% in stage 1 hypertensive patients. The screening test most advocated is the aldosterone-to-renin ratio (ARR), and when the ARR is >20 the following confirmatory tests should be carried out; the captopril challenge test, frusemide-upright test, or saline infusion test. Adrenal CT is not accurate for distinguishing between an aldosterone-producing adenoma (APA) and idiopathic hyperaldosteronism (IHA). Adrenal venous sampling (AVS) is therefore essential for selecting the appropriate therapy in patients a high probability of PA who require surgical treatment. Rapid cortisol assays during AVS to monitor cortisol levels can reduce the failure associated with AVS. We have developed a new rapid cortisol assay using immunochromatography, in which cortisol concentration can be measured within 6 min. Using this technique, the success rate of AVS improved to 93%. IHA underlies about one-half of cases with PA; treatment with eplerenone (100 mg twice a daily), a specific mineralocorticoid receptor antagonist, results in substantial improvement in hypertension, with fewer side effects compared to spironolactone.

Benidipine reduces albuminuria and plasma aldosterone in mild-to-moderate stage chronic kidney disease with albuminuria

Benidipine inhibits both L- and T-type Ca channels, and has been shown to dilate the efferent arterioles as effectively as the afferent arterioles. In this study, we conducted an open-label and randomized trial to compare the effects of benidipine with those of amlodipine on blood pressure (BP), albuminuria and aldosterone concentration in hypertensive patients with mild-to-moderate stage chronic kidney disease (CKD). Patients with BP ≥ 130/80 mm Hg, with estimated glomerular filtration rate (eGFR) of 30-90 ml min(-1) per 1.73 m(2), and with albuminuria>30 mg per g creatinine (Cr), despite treatment with the maximum recommended dose of angiotensin II receptor blockers (ARBs) were randomly assigned to two groups. Patients received either of the following two treatment regimens: 2 mg per day benidipine, which was increased up to a dose of 8 mg per day (n=52), or 2.5 mg per day amlodipine, which was increased up to a dose of 10  mg per day (n=52). After 6 months of treatment, a significant and comparable reduction in the systolic and diastolic BP was observed in both groups. The decrease in the urinary albumin to Cr ratio in the benidipine group was significantly lower than that in the amlodipine group. Although plasma renin activity was not different in the two groups, plasma aldosterone levels were significantly decreased in the benidipine group. Moreover, urinary Na/K ratio was significantly decreased in the benidipine group but remained unchanged in the serum. It may be concluded that benidipine results in a greater reduction of plasma aldosterone and albuminuria than amlodipine, and that these effects are independent of BP reduction.

Prognostic effects of combined treatment with calcium channel blockers and statins in patients with coronary narrowing: from the Japanese Coronary Artery Disease study

Calcium channel blockers (CCB) and statins are frequently prescribed for patients with coronary artery disease (CAD) complicated by hypertension and/or hypercholesterolemia. CCB have pleiotropic actions beyond their blood pressure-lowering effect, while statins have pleiotropic actions beyond their cholesterol-lowering effect. We assessed the hypothesis that combined treatment with CCB and statins has additional prognostic benefits resulting from potential additive or synergistic pleiotropic actions of both classes of drugs in the Japanese CAD (JCAD) study population. The JCAD study consisted of 13,812 patients with angiographically demonstrable significant coronary narrowing in at least 1 of 3 major coronary arteries who were followed-up for a mean of 2.7 years (follow-up rate, 88.4%). The primary endpoint of the present study was all cardiovascular events. We compared the event rate between patients receiving neither CCB nor statins and those receiving each drug alone or as a combination treatment using propensity score matching analysis. The rate of all events was 62.8 per 1,000 patient-years in the JCAD study. Kaplan-Meier analysis with the log-rank test showed no statistically significant difference in the event rate in each comparison. In conclusion, there may be no additional prognostic benefit beyond the blood-pressure-lowering and cholesterol-lowering effects in the combined treatment with CCB and statins for angiographically documented CAD patients.

Benidipine, a dihydropyridine L-type/T-type calcium channel blocker, affords additive benefits for prevention of cardiorenal injury in hypertensive rats

OBJECTIVES

Benidipine is a dihydropyridine calcium channel blocker inhibiting not only L-type but also T-type calcium channels. To elucidate potential additive benefit of benidipine for prevention of cardiorenal injury, we compared the cardiac and renal protective effects of equihypotensive doses of benidipine and cilnidipine in stroke-prone spontaneously hypertensive rats (SHRSP).

METHODS

SHRSP were divided into five groups, and were given vehicle, benidipine at 1 or 3 mg/kg per day, or cilnidipine at 1 or 3 mg/kg per day for 7 weeks, and the protective effects against cardiorenal injury were compared among each group.

RESULTS

Benidipine and cilnidipine at the same doses exerted comparable hypotensive effects on SHRSP throughout the treatment. Despite equihypotensive effects between both drugs, benidipine prevented cardiac hypertrophy, fibrosis, and inflammation to a greater extent than cilnidipine. Moreover, benidipine prevented glomerulosclerosis, tubulointerstitial injury, and renal inflammation more than cilnidipine. To elucidate the underlying mechanism of more beneficial effects of benidipine than cilnidipine, we compared the effects of these drugs on cardiac and renal oxidative stress, and aldosterone in SHRSP. Benidipine reduced both cardiac and renal NADPH oxidase activities in SHRSP more than cilnidipine, being associated with more attenuation of cardiac and renal superoxide by benidipine. Furthermore, serum aldosterone was significantly reduced by benidipine but not by cilnidipine.

CONCLUSION

Benidipine exerted more protective effects against cardiorenal injury of hypertensive rats than cilnidipine, through more attenuation of oxidative stress than cilnidipine, and the reduction of aldosterone. Benidipine, via blockade of T-type calcium channels, seems to elicit additive benefits for prevention of hypertensive cardiorenal injury.

The L-, N-, and T-type triple calcium channel blocker benidipine acts as an antagonist of mineralocorticoid receptor, a member of nuclear receptor family

Aldosterone-induced activation of mineralocorticoid receptor, a member of the nuclear receptor family, results in increased tissue damage such as vascular inflammation and cardiac and perivascular fibrosis. Benidipine, a long-lasting dihydropyridine calcium channel blocker, is used for hypertension and angina. Benidipine exhibits pleiotropic pharmacological features such as renoprotective and cardioprotective effects through triple blockade of L-, N-, and T-type calcium channels. However, the mechanism of additional beneficial effects on end-organ damage is poorly understood. Here, we examined the effects of benidipine and other calcium channel blockers on aldosterone-induced mineralocorticoid receptor activation using luciferase reporter assay system. Benidipine showed more potent activity than efonidipine, amlodipine, or azelnidipine. Benidipine depressed the response to higher concentrations of aldosterone, whereas pretreatment of eplerenone, a steroidal mineralocorticoid receptor antagonist, did not. Binding studies using [(3)H] aldosterone indicated that benidipine and other calcium channel blockers competed for binding to mineralocorticoid receptor. Benidipine and other calcium channel blockers showed antagonistic activity on Ser810 to Leu mutant mineralocorticoid receptor, which is identified in patients with early-onset hypertension. On the other hand, eplerenone partially activated the mutant. Results of analysis using optical isomers of benidipine indicated that inhibitory effect of aldosterone-induced mineralocorticoid receptor activation was independent of its primary blockade of calcium channels. These results suggested that benidipine directly inhibits aldosterone-induced mineralocorticoid receptor activation, and the antagonistic activity might contribute to the drug's pleiotropic pharmacological features.

Regulation of adrenal aldosterone production by serine protease prostasin

A serine protease prostasin has been demonstrated to have a pivotal role in the activation of the epithelial sodium channel. Systemic administration of adenovirus carrying human prostasin gene in rats resulted in an increase in plasma prostasin and aldosterone levels. However, the mechanism by which the elevation of prostasin levels in the systemic circulation stimulated the plasma aldosterone levels remains unknown. Therefore, we examined if prostasin increases the aldosterone synthesis in a human adrenocortical cell line (H295R cells). Luciferase assay using CYP11B2 promoter revealed that prostasin significantly increased the transcriptional activity of CYP11B2. Prostasin significantly increased both CYP11B2 mRNA expression and aldosterone production in a dose-dependent manner. Surprisingly, treatment with camostat mesilate, a potent prostasin inhibitor, had no effect on the aldosterone synthesis by prostasin and also a protease-dead mutant of prostasin significantly stimulated the aldosterone production. A T-type/L-type calcium channel blocker and a protein kinase C (PKC) inhibitor significantly reduced the aldosterone synthesis by prostasin. Our findings suggest a stimulatory effect of prostasin on the aldosterone synthesis by adrenal gland through the nonproteolytic action and indicate a new role of prostasin in the systemic circulation.

Impact of Long-Acting Calcium Channel Blockers on the Prognosis of Patients with Coronary Artery Disease with and without Chronic Kidney Disease: A Comparison of Three Drugs

Calcium channel blockers (CCBs) can prevent cardiovascular events in patients with coronary artery disease (CAD). This study looked retrospectively at the prognosis of CAD in hypertensive patients with CAD who had undergone a coronary angiograph, had been given a CCB (benidipine [ n = 66], amlodipine [ n = 45], or long-acting nifedipine [ n = 31]) on hospital discharge and were then followed up for a mean ± SD of 5.2 ± 2.9 years. Systolic/diastolic blood pressure for all 142 patients decreased significantly from a mean ± SD of 137 ± 20/74 ± 15 mmHg to 129 ± 20/71 ± 12 mmHg. Major adverse cardiovascular events (MACE) occurred in 15 patients. Chronic kidney disease (CKD) was a significant risk factor for MACE (hazard ratio 2.35, 95% confidence intervals 1.45, 3.80). Benidipine was superior to nifedipine in preventing MACE in patients both with and without CKD. In conclusion, benidipine and amlodipine reduced the frequency of MACE in hypertensive patients with CAD, particularly in those with complicating CKD.

Within-patient reproducibility of the aldosterone: renin ratio in primary aldosteronism

The plasma aldosterone concentration:renin ratio (ARR) is widely used for the screening of primary aldosteronism, but its reproducibility is unknown. We, therefore, investigated the within-patient reproducibility of the ARR in a prospective multicenter study of consecutive hypertensive patients referred to specialized centers for hypertension in Italy. After the patients were carefully prepared from the pharmacological standpoint, the ARR was determined at baseline in 1136 patients and repeated after, on average, 4 weeks in the patients who had initially an ARR > or =40 and in 1 of every 4 of those with an ARR <40. The reproducibility of the ARR was assessed with Passing and Bablok and Deming regression, coefficient of reproducibility, and Bland-Altman and Mountain plots. Within-patient ARR comparison was available in 268 patients, of whom 49 had an aldosterone-producing adenoma, on the basis of the "4-corner criteria." The ARR showed a highly significant within-patient correlation (r=0.69; P<0.0001) and reproducibility. Bland-Altman plot showed no proportional, magnitude-related, or absolute systematic error between the ARR; moreover, only 7% of the values, for example, slightly more than what could be expected by chance, fell out of the 95% CI for the between-test difference. The accuracy of each ARR for pinpointing aldosterone-producing adenoma patients was approximately 80%. Thus, although it was performed under different conditions in a multicenter study, the ARR showed a good within-patient reproducibility. Hence, contrary to previously claimed poor reproducibility of the ARR, these data support its use for the screening of primary aldosteronism.

Azelnidipine inhibits aldosterone synthesis and secretion in human adrenocortical cell line NCI-H295R

Blockade of a mineralocorticoid receptor is a clinically useful approach to the prevention of cardiovascular disease. The present study was designed to evaluate the effect of azelnidipine, a unique dihydropyridine Ca(2+) channel blocker, on aldosterone production in the human adrenocortical cell line NCI-H295R. Azelnidipine inhibited angiotensin II- and KCl-induced expression of steroid 11beta-hydroxylase, steroid 18-hydroxylase, and the alpha1H subunit of the T-type Ca(2+) channel, and suppressed steroid biosynthesis in H295R cells by the same amount as efonidipine. On the basis of these findings, azelnidipine appears to suppress steroid biosynthesis in H295R cells beyond the blockade of L-type calcium channels.

Molecular and clinical investigations in patients with low-renin hypertension

Interactions between the renin-angiotensin-aldosterone system and other mechanisms determining sodium balance are important in the pathophysiology of hypertension. Low-renin hypertension is a common type of resistant hypertension and is often associated with increased sodium retention. The importance of investigation, factors determining renin and aldosterone levels, and drug therapies in low-renin hypertension are reviewed.