Effects of thiazides and new findings on kidney stones and dysglycemic side effects.

Thiazide and thiazide-like diuretics (thiazides) belong to the most frequently prescribed drugs worldwide. By virtue of their natriuretic and vasodilating properties, thiazides effectively lower blood pressure and prevent adverse cardiovascular outcomes. In addition, through their unique characteristic of reducing urine calcium, thiazides are also widely employed for the prevention of kidney stone recurrence and reduction of bone fracture risk. Since their introduction into clinical medicine in the early 1960s, thiazides have been recognized for their association with metabolic side effects, particularly impaired glucose tolerance, and new-onset diabetes mellitus. Numerous hypotheses have been advanced to explain thiazide-induced glucose intolerance, yet underlying mechanisms remain poorly defined. Regrettably, the lack of understanding and unpredictability of these side effects has prompted numerous physicians to refrain from prescribing these effective, inexpensive, and widely accessible drugs. In this review, we outline the pharmacology and mechanism of action of thiazides, highlight recent advances in the understanding of thiazide-induced glucose intolerance, and provide an up-to-date discussion on the role of thiazides in kidney stone prevention.

Diferencias en función del sexo en las características clínicas y resultados del ensayo clínico CLOROTIC (combinación de diuréticos de asa con tiazidas en la insuficiencia cardiaca descompensada) / Sex differences in clinical characteristics and outcomes in the CLOROTIC (combining loop with thiazide diuretics for decompensated heart failure) trial

ObjetivoEvaluar si existen diferencias en los resultados del ensayo clínico CLOROTIC según el sexo. Métodos Subanálisis del ensayo CLOROTIC, que evaluó la eficacia y la seguridad de añadir hidroclorotiazida (HCTZ) o placebo a furosemida intravenosa en pacientes con insuficiencia cardiaca aguda (ICA). Los resultados primarios y secundarios incluyeron cambios en el peso y la disnea a las 72 y 96horas, medidas de la respuesta diurética y la mortalidad y reingresos a los 30 y 90días. Se evaluó la influencia del sexo en los resultados primarios y secundarios y de seguridad. Resultados De los 230 pacientes incluidos, 111 (48%) eran mujeres, que tenían más edad y valores más elevados de fracción de eyección ventricular izquierda. Los hombres tenían más cardiopatía isquémica, enfermedad pulmonar obstructiva crónica y mayor valor de péptidos natriuréticos. La adición de HCTZ a furosemida se asoció con una mayor pérdida de peso a las 72/96horas y mejor respuesta diurética a las 24horas en comparación con el placebo, sin diferencias significativas según el sexo (ningún valor de p para la interacción fue significativo). El deterioro de la función renal fue más frecuente en mujeres (OR: 8,68; IC95%: 3,41-24,63) que en varones (OR: 2,5; IC95%: 0,99-4,87), p=0,027. No hubo diferencias en la mortalidad ni en los reingresos a los 30/90días. Conclusión La adición de HCTZ a furosemida intravenosa es una estrategia eficaz para mejorar la respuesta diurética en la ICA sin diferencias según el sexo. Sin embargo, el deterioro de la función renal es más frecuente en las mujeres. (AU)

Aims The addition of hydrochlorothiazide (HCTZ) to furosemide improved the diuretic response in patients with acute heart failure (AHF) in the CLOROTIC trial. Our aim was to evaluate if there were differences in clinical characteristics and outcomes according to sex. Methods This is a post hoc analysis of the CLOROTIC trial, including 230 patients with AHF randomized to receive HCTZ or placebo in addition to an intravenous furosemide regimen. The primary and secondary outcomes included changes in weight and patient-reported dyspnoea 72 and 96h after randomization, metrics of diuretic response and mortality/rehospitalizations at 30 and 90days. The influence of sex on primary, secondary and safety outcomes was evaluated. Results One hundred and eleven (48%) women were included in the study. Women were older and had higher values of left ventricular ejection fraction. Men had more ischemic cardiomyopathy and chronic obstructive pulmonary disease and higher values of natriuretic peptides. The addition of HCTZ to furosemide was associated to a greatest weight loss at 72/96h, better metrics of diuretic response and higher 24-h diuresis compared to placebo without significant differences according to sex (all P-values for interaction were not significant). Worsening renal function occurred more frequently in women (OR: 8.68; 95%CI: 3.41-24.63) than men (OR: 2.5; 95%CI: 0.99-4.87), P=.027. There were no differences in mortality or rehospitalizations at 30/90days. Conclusion Adding HCTZ to intravenous furosemide is an effective strategy to improve diuretic response in AHF with no difference according to sex, but worsening renal function was more frequent in women. (AU)

Diferencias en función del sexo en las características clínicas y resultados del ensayo clínico CLOROTIC (combinación de diuréticos de asa con tiazidas en la insuficiencia cardiaca descompensada) / Sex differences in clinical characteristics and outcomes in the CLOROTIC (combining loop with thiazide diuretics for decompensated heart failure) trial

ObjetivoEvaluar si existen diferencias en los resultados del ensayo clínico CLOROTIC según el sexo. Métodos Subanálisis del ensayo CLOROTIC, que evaluó la eficacia y la seguridad de añadir hidroclorotiazida (HCTZ) o placebo a furosemida intravenosa en pacientes con insuficiencia cardiaca aguda (ICA). Los resultados primarios y secundarios incluyeron cambios en el peso y la disnea a las 72 y 96horas, medidas de la respuesta diurética y la mortalidad y reingresos a los 30 y 90días. Se evaluó la influencia del sexo en los resultados primarios y secundarios y de seguridad. Resultados De los 230 pacientes incluidos, 111 (48%) eran mujeres, que tenían más edad y valores más elevados de fracción de eyección ventricular izquierda. Los hombres tenían más cardiopatía isquémica, enfermedad pulmonar obstructiva crónica y mayor valor de péptidos natriuréticos. La adición de HCTZ a furosemida se asoció con una mayor pérdida de peso a las 72/96horas y mejor respuesta diurética a las 24horas en comparación con el placebo, sin diferencias significativas según el sexo (ningún valor de p para la interacción fue significativo). El deterioro de la función renal fue más frecuente en mujeres (OR: 8,68; IC95%: 3,41-24,63) que en varones (OR: 2,5; IC95%: 0,99-4,87), p=0,027. No hubo diferencias en la mortalidad ni en los reingresos a los 30/90días. Conclusión La adición de HCTZ a furosemida intravenosa es una estrategia eficaz para mejorar la respuesta diurética en la ICA sin diferencias según el sexo. Sin embargo, el deterioro de la función renal es más frecuente en las mujeres. (AU)

Aims The addition of hydrochlorothiazide (HCTZ) to furosemide improved the diuretic response in patients with acute heart failure (AHF) in the CLOROTIC trial. Our aim was to evaluate if there were differences in clinical characteristics and outcomes according to sex. Methods This is a post hoc analysis of the CLOROTIC trial, including 230 patients with AHF randomized to receive HCTZ or placebo in addition to an intravenous furosemide regimen. The primary and secondary outcomes included changes in weight and patient-reported dyspnoea 72 and 96h after randomization, metrics of diuretic response and mortality/rehospitalizations at 30 and 90days. The influence of sex on primary, secondary and safety outcomes was evaluated. Results One hundred and eleven (48%) women were included in the study. Women were older and had higher values of left ventricular ejection fraction. Men had more ischemic cardiomyopathy and chronic obstructive pulmonary disease and higher values of natriuretic peptides. The addition of HCTZ to furosemide was associated to a greatest weight loss at 72/96h, better metrics of diuretic response and higher 24-h diuresis compared to placebo without significant differences according to sex (all P-values for interaction were not significant). Worsening renal function occurred more frequently in women (OR: 8.68; 95%CI: 3.41-24.63) than men (OR: 2.5; 95%CI: 0.99-4.87), P=.027. There were no differences in mortality or rehospitalizations at 30/90days. Conclusion Adding HCTZ to intravenous furosemide is an effective strategy to improve diuretic response in AHF with no difference according to sex, but worsening renal function was more frequent in women. (AU)

Circulating microRNA Biomarkers of Thiazide Response in Hypertension.

BACKGROUND: Thiazide diuretics are the second most frequently prescribed class of antihypertensives, but up to 50% of patients with hypertension have minimal antihypertensive response to thiazides. We explored circulating microRNAs (miRNAs) in search of predictive biomarkers of thiazide response. METHODS AND RESULTS: We profiled 754 miRNAs in baseline plasma samples of 36 hypertensive European American adults treated with hydrochlorothiazide, categorized into responders (n=18) and nonresponders (n=18) on the basis of diastolic blood pressure response to hydrochlorothiazide. miRNAs with ≥2.5-fold differential expression between responders and nonresponders were considered for validation in 3 cohorts (n=50 each): hydrochlorothiazide-treated European Americans, chlorthalidone-treated European Americans, and hydrochlorothiazide-treated Black individuals. Different blood pressure phenotypes including categorical (responder versus nonresponder) and continuous diastolic blood pressure and systolic blood pressure were tested for association with the candidate miRNA expression using multivariate regression analyses adjusting for age, sex, and baseline blood pressure. After quality control, 74 miRNAs were available for screening, 19 of which were considered for validation. In the validation cohort, miR-193b-3p and 30d-5p showed significant associations with continuous SBP or diastolic blood pressure response or both, to hydrochlorothiazide in European Americans at Benjamini-Hochberg adjusted P<0.05. In the combined analysis of validation cohorts, let-7g (odds ratio, 0.6 [95% CI, 0.4-0.8]), miR-142-3p (odds ratio, 1.1 [95% CI, 1.0, 1.2]), and miR-423-5p (odds ratio, 0.7 [95% CI, 0.5-0.9]) associated with categorical diastolic blood pressure response at Benjamini-Hochberg adjusted P<0.05. Predicted target genes of the 5 miRNAs were mapped to key hypertension pathways: lysine degradation, fatty acid biosynthesis, and metabolism. CONCLUSIONS: The above identified circulating miRNAs may have a potential for clinical use as biomarkers for thiazide diuretic selection in hypertension. REGISTRATION: URL: ClinicalTrials.gov. Unique identifiers: NCT00246519, NCT01203852, NCT00005520.

Kinase Scaffold Cab39 Is Necessary for Phospho-Activation of the Thiazide-Sensitive NCC.

BACKGROUND: Potassium regulates the WNK (with no lysine kinase)-SPAK (STE20/SPS1-related proline/alanine-rich kinase) signaling axis, which in turn controls the phosphorylation and activation of the distal convoluted tubule thiazide-sensitive NCC (sodium-chloride cotransporter) for sodium-potassium balance. Although their roles in the kidney have not been investigated, it has been postulated that Cab39 (calcium-binding protein 39) or Cab39l (Cab39-like) is required for SPAK/OSR1 (oxidative stress response 1) activation. This study demonstrates how they control the WNK-SPAK/OSR1-NCC pathway. METHODS: We created a global knockout of Cab39l and a tamoxifen-inducible, NCC-driven, Cab39 knockout. The 2 lines were crossed to generate Cab39-DKO (Cab39 double knockout) animals. Mice were studied under control and low-potassium diet, which activates WNK-SPAK/OSR1-NCC phosphorylation. Western blots were used to assess the expression and phosphorylation of proteins. Blood and urine electrolytes were measured to test for compromised NCC function. Immunofluorescence studies were conducted to localize SPAK and OSR1. RESULTS: Both Cab39l and Cab39 are expressed in distal convoluted tubule, and only the elimination of both leads to a striking absence of NCC phosphorylation. Cab39-DKO mice exhibited a loss-of-NCC function, like in Gitelman syndrome. In contrast to the apical membrane colocalization of SPAK with NCC in wild-type mice, SPAK and OSR1 become confined to intracellular puncta in the Cab39-DKO mice. CONCLUSIONS: In the absence of Cab39 proteins, NCC cannot be phosphorylated, resulting in a Gitelman-like phenotype. Cab39 proteins function to localize SPAK at the apical membrane with NCC, reminiscent of the Cab39 yeast homolog function, translocating kinases during cytokinesis.

[Efficacy and Organoprotection of Triple Combinations in the Treatment of Arterial Hypertension].

The 2022 draft Russian guidelines on arterial hypertension recommend initiation of antihypertensive therapy with a combination of drugs in most patients with blood pressure above 150 / 90 mm Hg and / or in the presence of high-risk criteria. In 2021, the results of a 12-year analysis of the Brisighella Heart Study (BHS) were published. The aim of this study was to compare the use of different triple antihypertensive drug combinations in an Italian cohort of patients in real-life clinical practice. Combination antihypertensive therapy with a renin-angiotensin-aldosterone system inhibitor, amlodipine, and thiazide/thiazide-like diuretics provides a better blood pressure control compared to other antihypertensive drug combinations. The use of the triple combination of amlodipine/indapamide/perindopril is associated with a better metabolic profile than any other considered combination of antihypertensive drugs and a more pronounced organ-protective effect.

Thiazides Attenuate Insulin Secretion Through Inhibition of Mitochondrial Carbonic Anhydrase 5b in ß -Islet Cells in Mice.

SIGNIFICANCE STATEMENT: Thiazide diuretics (thiazides) are among the most widely prescribed drugs worldwide, but their use is associated with glucose intolerance and new-onset diabetes mellitus. The molecular mechanisms remain elusive. Our study reveals that thiazides attenuate insulin secretion through inhibition of the mitochondrial carbonic anhydrase isoform 5b (CA5b) in pancreatic ß cells. We furthermore discovered that pancreatic ß cells express only one functional carbonic anhydrase isoform, CA5b, which is critical in replenishing oxaloacetate in the mitochondrial tricarboxylic acid (TCA) cycle (anaplerosis). These findings explain the mechanism for thiazide-induced glucose intolerance and reveal a fundamental role of CA5b in TCA cycle anaplerosis and insulin secretion in ß cells. BACKGROUND: Thiazide diuretics are associated with glucose intolerance and new-onset diabetes mellitus. Previous studies demonstrated that thiazides attenuate insulin secretion, but the molecular mechanisms remain elusive. We hypothesized that thiazides attenuate insulin secretion via one of the known molecular thiazide targets in ß cells. METHODS: We performed static insulin secretion experiments with islets of wild-type, Sodium/chloride co-transporter (NCC) (SLC12A3), and sodium-driven chloride/bicarbonate exchanger (NDCBE) (SLC4A8) knock-out (KO) mice and with murine Min6 cells with individual knockdown of carbonic anhydrase (CA) isoforms to identify the molecular target of thiazides in ß cells. CA isoform 5b (CA5b) KO mice were then used to assess the role of the putative thiazide target CA5b in ß -cell function and in mediating thiazide sensitivity in vitro and in vivo . RESULTS: Thiazides inhibited glucose- and sulfonylurea-stimulated insulin secretion in islets and Min6 cells at pharmacologically relevant concentrations. Inhibition of insulin secretion by thiazides was CO 2 /HCO 3- -dependent, not additive to unselective CA inhibition with acetazolamide, and independent of extracellular potassium. By contrast, insulin secretion was unaltered in islets of mice lacking the known molecular thiazide targets NCC or NDCBE. CA expression profiling with subsequent knockdown of individual CA isoforms suggested mitochondrial CA5b as a molecular target. In support of these findings, thiazides significantly attenuated Krebs cycle anaplerosis through reduction of mitochondrial oxaloacetate synthesis. CA5b KO mice were resistant to thiazide-induced glucose intolerance, and thiazides did not alter insulin secretion in CA5b KO islets. CONCLUSIONS: Thiazides attenuate insulin secretion via inhibition of the mitochondrial CA5b isoform in ß cells of mice.

Structure and thiazide inhibition mechanism of the human Na-Cl cotransporter.

The sodium-chloride cotransporter (NCC) is critical for kidney physiology1. The NCC has a major role in salt reabsorption in the distal convoluted tubule of the nephron2,3, and mutations in the NCC cause the salt-wasting disease Gitelman syndrome4. As a key player in salt handling, the NCC regulates blood pressure and is the target of thiazide diuretics, which have been widely prescribed as first-line medications to treat hypertension for more than 60 years5-7. Here we determined the structures of human NCC alone and in complex with a commonly used thiazide diuretic using cryo-electron microscopy. These structures, together with functional studies, reveal major conformational states of the NCC and an intriguing regulatory mechanism. They also illuminate how thiazide diuretics specifically interact with the NCC and inhibit its transport function. Our results provide critical insights for understanding the Na-Cl cotransport mechanism of the NCC, and they establish a framework for future drug design and for interpreting disease-related mutations.

Effectiveness of thiazide and thiazide-like diuretics in advanced chronic kidney disease: a systematic review and meta-analysis.

BACKGROUND AND OBJECTIVE: Thiazide diuretics are first-line drugs for the treatment of hypertension, but hypertension treatment guidelines have systematically discouraged their use in patients with advanced chronic kidney disease (CKD). For the first time, a systematic review and random-effects meta-analysis were performed to assess the effectiveness of thiazides and thiazide-like diuretics to treat hypertension in patients with stages 3b, 4, and 5 CKD. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: A systematic review and random-effects meta-analysis that included a literature search using the following databases were performed: MEDLINE through PubMed, Cochrane Database of Systematic Reviews (CDSR) and Cochrane Central Register of Controlled Trials (CENTRAL) through the Cochrane Library, Embase, and ISI - Web of Science (all databases). Prospective studies that evaluated the effectiveness of thiazide and thiazide-like diuretics in individuals with a GFR < 45 mL/min/1.73 m2 were included. RESULTS: Five clinical trials, totaling 214 participants, were included, and the mean GFR ranged from 13.0 ± 5.9 mL/min/1.73 m2 to 26.8 ± 8.8 mL/min/1.73 m2. There was evidence of a reduction in mean blood pressure and in GFR, as well as in fractional sodium excretion and fractional chloride excretion. CONCLUSION: Thiazide and thiazide-like diuretics seem to maintain their effectiveness in lowering blood pressure in patients with advanced chronic kidney disease. These findings should spur new prospective randomized trials and spark discussions, particularly about upcoming hypertension guidelines.

Influence of administration time and sex on natriuretic, diuretic, and kaliuretic effects of diuretics.

Sex differences in renal function and blood pressure have been widely described across many species. Blood pressure dips during sleep and peaks in the early morning. Similarly, glomerular filtration rate, filtered electrolyte loads, urine volume, and urinary excretion all exhibit notable diurnal rhythms, which reflect, in part, the regulation of renal transporter proteins by circadian clock genes. That regulation is sexually dimorphic; as such, sex and time of day are not two independent regulators of kidney function and blood pressure. The objective of the present study was to assess the effect of sex and administration time on the natriuretic and diuretic effects of loop, thiazide, and K+-sparing diuretics, which are common treatments for hypertension. Loop diuretics inhibit Na+-K+-2Cl- cotransporters on the apical membrane of the thick ascending limb, thiazide diuretics inhibit Na+-Cl- cotransporters on the distal convoluted tubule, and K+-sparing diuretics inhibit epithelial Na+ channels on the connecting tubule and collecting duct. We simulated Na+ transporter inhibition using sex- and time-of-day-specific computational models of mouse kidney function. The simulation results highlighted significant sex and time-of-day differences in the drug response. Loop diuretics induced larger natriuretic and diuretic effects during the active phase. The natriuretic and diuretic effects of thiazide diuretics exhibited sex and time-of-day differences, whereas these effects of K+-sparing diuretics exhibited a significant time-of-day difference in females only. The kaliuretic effect depended on the type of diuretics and time of administration. The present computational models can be a useful tool in chronotherapy, to tailor drug administration time to match the body's diurnal rhythms to optimize the drug effect.NEW & NOTEWORTHY Sex influences cardiovascular disease, and the timing of onset of acute cardiovascular events exhibits circadian rhythms. Kidney function also exhibits sex differences and circadian rhythms. How do the natriuretic and diuretic effects of diuretics, a common treatment for hypertension that targets the kidneys, differ between the sexes? And how do these effects vary during the day? To answer these questions, we conducted computer simulations to assess the effects of loop, thiazide, and K+-sparing diuretics.

Pairwise comparison of hydrochlorothiazide and chlorthalidone responses among hypertensive patients.

This study conducted a pairwise comparison of antihypertensive and metabolic effects of hydrochlorothiazide (HCTZ) and chlorthalidone (CTD) at 25 mg/day in the same individuals to address the clinical dilemma on preferred thiazide for hypertension (HTN) management. We included 15 African American (AA) and 35 European American (EA) patients with HTN treated with HCTZ and CTD as part of the Pharmacogenomic Evaluation of Antihypertensive Responses (PEAR) and PEAR-2 trials, respectively. Mean reduction in systolic/diastolic blood pressure (SBP/DBP) with HCTZ versus CTD was 8/5 versus 16/8 mmHg among EA patients (p < 1.0e-5 SBP, p = 0.002 DBP) and 11/8 versus 20/11 mmHg among AA patients (p = 0.03 SBP, p = 0.22 DBP). While CTD showed clinically meaningful benefit over HCTZ in two-thirds of participants with respect to SBP reduction and half of EA patients with respect to DBP reduction, a majority of AA patients (53%) showed similar DBP reduction with both thiazides. Sixty percent of AA patients and 29% of EA patients attained blood pressure (BP) <140/90 mmHg with both thiazides. Mean potassium (K+) reduction was greater with CTD compared to HCTZ both in EA patients (mean difference = 0.35, p = 0.0002) and AA patients (0.49, p = 0.043). While 31% of AA patients developed severe hypokalemia on CTD, <5% of others developed severe hypokalemia. Although 46% of AA patients on CTD required K+ supplementation, only 6%-11% of others required supplementation. Overall, in the majority of EA patients, CTD was superior to HCTZ, whereas among AA patients, it was superior in a minority, and was associated with significant potassium-related risk, suggesting that guideline preferences for CTD over HCTZ are reasonable in EA patients but may be less reasonable in AA patients, particularly if the target is <140/90 mmHg.

Current antihypertensive treatment and treatment-resistant hypertension in Japanese patients with chronic kidney disease.

BACKGROUND: Hypertension is an important prognostic predictor in patients with chronic kidney disease (CKD), and the recommended target blood pressure has been continuously revised. This study aimed to reveal the current antihypertensive practices in Japanese patients with CKD. METHODS: In the Fukuoka Kidney disease Registry, we extracted 3664 non-dialysis-dependent patients with CKD. Apparent treatment-resistant hypertension (aTRH) was defined as a failure of blood-pressure control treated with three antihypertensive medication classes or a treatment with ≥ 4 classes regardless of blood pressure. The blood-pressure control complied with the target blood pressure recommended by the KDIGO 2012 guideline. RESULTS: The median age of the patients was 67 years, body mass index (BMI) was 23 kg/m2, and estimated glomerular filtration rate (eGFR) was 40 mL/min/1.73 m2. The number of patients with unachieved blood-pressure control was 1933, of whom 26% received ≥ 3 classes of antihypertensive medications. The first choice of medication was renin-angiotensin system inhibitors, followed by calcium-channel blockers. The rate of thiazide use was low in all CKD stages (3-11%). The prevalence of aTRH was 16%, which was significantly associated with BMI (odds ratio [95% confidence interval] per 1-standard deviation change, 1.38 [1.25-1.53]), decreased eGFR (1.87 [1.57-2.23]), as well as age, diabetes mellitus, and chronic heart disease. CONCLUSIONS: Renal dysfunction and obesity are important risk factors of aTRH. Even under nephrologist care, most patients were treated with insufficient antihypertensive medications. It is important to prescribe sufficient classes of antihypertensive medications, including diuretics, and to improve patients' lifestyle habits.

The European and Japanese eel NaCl cotransporters ß exhibit chloride currents and are resistant to thiazide type diuretics.

The thiazide-sensitive Na+-Cl- cotransporter (NCC) is the major pathway for salt reabsorption in the mammalian distal convoluted tubule, and the inhibition of its function with thiazides is widely used for the treatment of arterial hypertension. In mammals and teleosts, NCC is present as one ortholog that is mainly expressed in the kidney. One exception, however, is the eel, which has two genes encoding NCC. The eNCCα is located in the kidney and eNCCß, which is present in the apical membrane of the rectum. Interestingly, the European eNCCß functions as a Na+-Cl- cotransporter that is nevertheless resistant to thiazides and is not activated by low-chloride hypotonic stress. However, in the Japanese eel rectal sac, a thiazide-sensitive NaCl transport mechanism has been described. The protein sequences between eNCCß and jNCCß are 98% identical. Here, by site-directed mutagenesis, we transformed eNCCß into jNCCß. Our data showed that jNCCß, similar to eNCCß, is resistant to thiazides. In addition, both NCCß proteins have high transport capacity with respect to their renal NCC orthologs and, in contrast to known NCCs, exhibit electrogenic properties that are reduced when residue I172 is substituted by A, G, or M. This is considered a key residue for the chloride ion-binding sites of NKCC and KCC. We conclude that NCCß proteins are not sensitive to thiazides and have electrogenic properties dependent on Cl-, and site I172 is important for the function of NCCß.

Effect of diuretics on plasma aldosterone and potassium in primary hypertension: A systematic review and meta-analysis.

AIM: By contrast with drugs inhibiting the renin-angiotensin-aldosterone system (RAAS), diuretics stimulate renin release by the kidneys. Although plasma aldosterone (PA) is thought to be mainly regulated by RAAS activity, serum potassium has been shown to be an important factor in animal models and humans. Here we perform a systematic review and meta-analysis of randomised controlled trials (RCT) in hypertension investigating the effects of diuretic therapy on PA and the correlation of change in PA with that of potassium and blood pressure (BP). METHODS: Three databases were searched: MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials (CENTRAL). Titles were first screened by title and abstract for relevance before full-text articles were assessed for eligibility according to a predefined inclusion/exclusion criteria. RESULTS: A total of 1139 articles were retrieved, of which 42 met the prespecified inclusion/exclusion criteria. The average standardised difference in mean PA was similar for all classes of diuretic: thiazide/thiazide-like 0.299 (95% confidence interval [CI] 0.150, 0.447), loop 0.927 (0.37, 1.49), MRA/potassium-sparing 0.265 (0.173, 0.357) and combination 0.466 (0.137, 0.796), Q = 6.33, P = .097. In subjects untreated with another antihypertensive, there was a significant relationship between change in PA and change in systolic BP but no relationship with the change in potassium. CONCLUSION: In RCTs of diuretic therapy in hypertension, there is an increase in PA with all classes of diuretic and no significant between-class heterogeneity. Change in PA is not related with potassium but correlates with the change in BP in subjects untreated with another antihypertensive medication.

Sex difference in kidney electrolyte transport III: Impact of low K intake on thiazide-sensitive cation excretion in male and female mice.

We compared the regulation of the NaCl cotransporter (NCC) in adaptation to a low-K (LK) diet in male and female mice. We measured hydrochlorothiazide (HCTZ)-induced changes in urine volume (UV), glomerular filtration rate (GFR), absolute (ENa, EK), and fractional (FENa, FEK) excretion in male and female mice on control-K (CK, 1% KCl) and LK (0.1% KCl) diets for 7 days. With CK, NCC-dependent ENa and FENa were larger in females than males as observed previously. However, with LK, HCTZ-induced ENa and FENa increased in males but not in females, abolishing the sex differences in NCC function as observed in CK group. Despite large diuretic and natriuretic responses to HCTZ, EK was only slightly increased in response to the drug when animals were on LK. This suggests that the K-secretory apparatus in the distal nephron is strongly suppressed under these conditions. We also examined LK-induced changes in Na transport protein expression by Western blotting. Under CK conditions females expressed more NCC protein, as previously reported. LK doubled both total (tNCC) and phosphorylated NCC (pNCC) abundance in males but had more modest effects in females. The larger effect in males abolished the sex-dependence of NCC expression, consistent with the measurements of function by renal clearance. LK intake did not change NHE3, NHE2, or NKCC2 expression, but reduced the amount of the cleaved (presumably active) form of γENaC. LK reduced plasma K to lower levels in females than males. These results indicated that males had a stronger NCC-mediated adaptation to LK intake than females.

The Forgotten Antiproteinuric Properties of Diuretics.

BACKGROUND: Although diuretics are one of the most widely used drugs by nephrologists, their antiproteinuric properties are not generally taken into consideration. SUMMARY: Thiazide diuretics have been shown to reduce proteinuria by >35% in several prospective controlled studies, and these values are markedly increased when combined with a low-salt diet. Thiazide-like diuretics (indapamide and chlorthalidone) have shown similar effectiveness. The antiproteinuric effect of mineralocorticoid receptor antagonists (spironolactone, eplerenone, and finerenone) has been clearly established through prospective and controlled studies, and treatment with finerenone reduces the risk of chronic kidney disease progression in type-2 diabetic patients. The efficacy of other diuretics such as amiloride, triamterene, acetazolamide, or loop diuretics has been less explored, but different investigations suggest that they might share the same antiproteinuric properties of other diuretics that should be evaluated through controlled studies. Although the inclusion of sodium-glucose cotransporter-2 inhibitors (SGLT2i) among diuretics is a controversial issue, their renoprotective and cardioprotective properties, confirmed in various landmark trials, constitute a true revolution in the treatment of patients with kidney disease. Recent subanalyses of these trials have shown that the early antiproteinuric effect induced by SGLT2i predicts long-term preservation of kidney function. Key Message: Whether the early reduction in proteinuria induced by diuretics other than finerenone and SGLT2i, as summarized in this review, also translates into long-term renoprotection requires further prospective and observational studies. In any case, it is important for the clinician to be aware of the antiproteinuric properties of drugs so often used in daily clinical practice.

Thiazide Use and Decreased Risk of Heart Failure in Nondiabetic Patients Receiving Intensive Blood Pressure Treatment.

The SPRINT (Systolic Blood Pressure Intervention Trial) study reported that intensive blood pressure (BP) treatment with a systolic BP target of <120 mm Hg decreased the risks of cardiovascular events. However, it remains unknown whether specific medications can further improve cardiovascular outcome in patients receiving intensive BP treatment. This study examined whether thiazide use improves cardiovascular outcome in patients receiving intensive BP treatment. We used data of nondiabetic patients receiving intensive BP treatment in the SPRINT study. The primary outcome was a composite end point of myocardial infarction, acute coronary syndrome, stroke, heart failure, or cardiovascular death. We analyzed hazard ratios for outcomes with 95% CIs in patients taking thiazides compared with those not taking thiazides using Cox proportional hazard models. This study included 2847 patients and the mean follow-up period was 3.3 years. The risk of primary outcome events was significantly lower in patients taking thiazides than in those not taking thiazides in both entire and propensity score-matched cohorts. Particularly, heart failure risk was significantly lower in those taking thiazides. These associations were also observed in various subgroups. In addition, thiazide use was associated with decreased risk of all-cause mortality. Hypokalemia occurred more frequently in patients taking thiazides than in those not taking thiazides. Thiazide use decreased risk of cardiovascular events, particularly heart failure, in nondiabetic high-risk patients receiving intensive BP treatment.

Renal Tubule Nedd4-2 Deficiency Stimulates Kir4.1/Kir5.1 and Thiazide-Sensitive NaCl Cotransporter in Distal Convoluted Tubule.

BACKGROUND: The potassium channel Kir4.1 forms the Kir4.1/Kir5.1 heterotetramer in the basolateral membrane of the distal convoluted tubule (DCT) and plays an important role in the regulation of the thiazide-sensitive NaCl cotransporter (NCC). Kidney-specific deletion of the ubiquitin ligase Nedd4-2 increases expression of NCC, and coexpression of Nedd4-2 inhibits Kir4.1/Kir5.1 in vitro. Whether Nedd4-2 regulates NCC expression in part by regulating Kir4.1/Kir5.1 channel activity in the DCT is unknown. METHODS: We used electrophysiology studies, immunoblotting, immunostaining, and renal clearance to examine Kir4.1/Kir5.1 activity in the DCT and NCC expression/activity in wild-type mice and mice with kidney-specific knockout of Nedd4-2, Kir4.1, or both. RESULTS: Deletion of Nedd4-2 increased the activity/expression of Kir4.1 in the DCT and also, hyperpolarized the DCT membrane. Expression of phosphorylated NCC/total NCC and thiazide-induced natriuresis were significantly increased in the Nedd4-2 knockout mice, but these mice were normokalemic. Double-knockout mice lacking both Kir4.1/Kir5.1 and Nedd4-2 in the kidney exhibited increased expression of the epithelial sodium channel α-subunit, largely abolished basolateral potassium ion conductance (to a degree similar to that of kidney-specific Kir4.1 knockout mice), and depolarization of the DCT membrane. Compared with wild-type mice, the double-knockout mice displayed inhibited expression of phosphorylated NCC and total NCC and had significantly blunted thiazide-induced natriuresis as well as renal potassium wasting and hypokalemia. However, NCC expression/activity was higher in the double-knockout mice than in Kir4.1 knockout mice. CONCLUSIONS: Nedd4-2 regulates Kir4.1/Kir5.1 expression/activity in the DCT and modulates NCC expression by Kir4.1-dependent and Kir4.1-independent mechanisms. Basolateral Kir4.1/Kir5.1 activity in the DCT partially accounts for the stimulation of NCC activity/expression induced by deletion of Nedd4-2.

Rapid Aldosterone-Mediated Signaling in the DCT Increases Activity of the Thiazide-Sensitive NaCl Cotransporter.

BACKGROUND: The NaCl cotransporter NCC in the kidney distal convoluted tubule (DCT) regulates urinary NaCl excretion and BP. Aldosterone increases NaCl reabsorption via NCC over the long-term by altering gene expression. But the acute effects of aldosterone in the DCT are less well understood. METHODS: Proteomics, bioinformatics, and cell biology approaches were combined with animal models and gene-targeted mice. RESULTS: Aldosterone significantly increases NCC activity within minutes in vivo or ex vivo. These effects were independent of transcription and translation, but were absent in the presence of high potassium. In vitro, aldosterone rapidly increased intracellular cAMP and inositol phosphate accumulation, and altered phosphorylation of various kinases/kinase substrates within the MAPK/ERK, PI3K/AKT, and cAMP/PKA pathways. Inhibiting GPR30, a membrane-associated receptor, limited aldosterone's effects on NCC activity ex vivo, and NCC phosphorylation was reduced in GPR30 knockout mice. Phosphoproteomics, network analysis, and in vitro studies determined that aldosterone activates EGFR-dependent signaling. The EGFR immunolocalized to the DCT and EGFR tyrosine kinase inhibition decreased NCC activity ex vivo and in vivo. CONCLUSIONS: Aldosterone acutely activates NCC to modulate renal NaCl excretion.