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American Journal of Physiology.... Dec 2022Amiloride has been shown to inhibit acid-sensing ion channels (ASICs), which contribute to ischemia-related muscle pain during exercise. The purpose of this study was to... (Randomized Controlled Trial)
Randomized Controlled Trial
Amiloride has been shown to inhibit acid-sensing ion channels (ASICs), which contribute to ischemia-related muscle pain during exercise. The purpose of this study was to determine if a single oral dose of amiloride would improve exercise tolerance and attenuate blood pressure during blood-flow-restricted (BFR) exercise in healthy adults. Ten subjects (4 females) performed isometric plantar flexion exercise with BFR (30% maximal voluntary contraction) after ingesting either a 10-mg dose of amiloride or a volume-matched placebo (random order). Time to failure, time-tension index (TTI), and perceived pain (visual analog scale) were compared between the amiloride and placebo trials. Mean blood pressure, heart rate, blood pressure index (BPI), and BPI normalized to TTI (BPI) were also compared between trials using both time-matched (TM and TM) and effort-matched (T and T) comparisons. Time to failure (+69.4 ± 63.2 s, < 0.01) and TTI (+1,441 ± 633 kg·s, = 0.02) were both significantly increased in the amiloride trial compared with placebo, despite no increase in pain (+0.4 ± 1.7 cm, = 0.46). In contrast, amiloride had no significant influence on the mean blood pressure or heart rate responses, nor were there any significant differences in BPI or BPI between trials when matched for time (all ≥ 0.13). When matched for effort, BPI was significantly greater in the amiloride trial (+5,300 ± 1,798 mmHg·s, = 0.01), likely owing to an increase in total exercise duration. In conclusion, a 10-mg oral dose of amiloride appears to significantly improve the tolerance to BFR exercise in healthy adults without influencing blood pressure responses.
Topics: Adult; Female; Humans; Male; Amiloride; Blood Pressure; Heart Rate; Hemodynamics; Regional Blood Flow; Resistance Training
PubMed: 36222880
DOI: 10.1152/ajpregu.00190.2022 -
JCI Insight Mar 2023Dietary potassium (K+) supplementation is associated with a lowering effect in blood pressure (BP), but not all studies agree. Here, we examined the effects of short-...
Dietary potassium (K+) supplementation is associated with a lowering effect in blood pressure (BP), but not all studies agree. Here, we examined the effects of short- and long-term K+ supplementation on BP in mice, whether differences depend on the accompanying anion or the sodium (Na+) intake and molecular alterations in the kidney that may underlie BP changes. Relative to the control diet, BP was higher in mice fed a high NaCl (1.57% Na+) diet for 7 weeks or fed a K+-free diet for 2 weeks. BP was highest on a K+-free/high NaCl diet. Commensurate with increased abundance and phosphorylation of the thiazide sensitive sodium-chloride-cotransporter (NCC) on the K+-free/high NaCl diet, BP returned to normal with thiazides. Three weeks of a high K+ diet (5% K+) increased BP (predominantly during the night) independently of dietary Na+ or anion intake. Conversely, 4 days of KCl feeding reduced BP. Both feeding periods resulted in lower NCC levels but in increased levels of cleaved (active) α and γ subunits of the epithelial Na+ channel ENaC. The elevated BP after chronic K+ feeding was reduced by amiloride but not thiazide. Our results suggest that dietary K+ has an optimal threshold where it may be most effective for cardiovascular health.
Topics: Mice; Animals; Blood Pressure; Sodium Chloride Symporters; Potassium, Dietary; Sodium Chloride; Epithelial Sodium Channels; Sodium; Thiazides; Dietary Supplements
PubMed: 36719746
DOI: 10.1172/jci.insight.156437 -
Experimental Physiology May 2024It has been proposed that diuretics can improve renal tissue oxygenation through inhibition of tubular sodium reabsorption and reduced metabolic demand. However, the...
It has been proposed that diuretics can improve renal tissue oxygenation through inhibition of tubular sodium reabsorption and reduced metabolic demand. However, the impact of clinically used diuretic drugs on the renal cortical and medullary microcirculation is unclear. Therefore, we examined the effects of three commonly used diuretics, at clinically relevant doses, on renal cortical and medullary perfusion and oxygenation in non-anaesthetised healthy sheep. Merino ewes received acetazolamide (250 mg; n = 9), furosemide (20 mg; n = 10) or amiloride (10 mg; n = 7) intravenously. Systemic and renal haemodynamics, renal cortical and medullary tissue perfusion and , and renal function were then monitored for up to 8 h post-treatment. The peak diuretic response occurred 2 h (99.4 ± 14.8 mL/h) after acetazolamide, at which stage cortical and medullary tissue perfusion and were not significantly different from their baseline levels. The peak diuretic response to furosemide occurred at 1 h (196.5 ± 12.3 mL/h) post-treatment but there were no significant changes in cortical and medullary tissue oxygenation during this period. However, cortical tissue fell from 40.1 ± 3.8 mmHg at baseline to 17.2 ± 4.4 mmHg at 3 h and to 20.5 ± 5.3 mmHg at 6 h after furosemide administration. Amiloride did not produce a diuretic response and was not associated with significant changes in cortical or medullary tissue oxygenation. In conclusion, clinically relevant doses of diuretic agents did not improve regional renal tissue oxygenation in healthy animals during the 8 h experimentation period. On the contrary, rebound renal cortical hypoxia may develop after dissipation of furosemide-induced diuresis.
Topics: Animals; Furosemide; Acetazolamide; Amiloride; Diuretics; Sheep; Female; Kidney Cortex; Kidney Medulla; Oxygen; Hemodynamics; Oxygen Consumption
PubMed: 38551893
DOI: 10.1113/EP091479 -
IScience Jun 2024The kidney is a vital organ responsible for water and sodium metabolism, while the primary function of amiloride is to promote the excretion of water and sodium. We...
The kidney is a vital organ responsible for water and sodium metabolism, while the primary function of amiloride is to promote the excretion of water and sodium. We investigated amiloride enhanced the sunitinib sensitivity in RCC. We found both sunitinib and amiloride displayed cytotoxicity and exerted the synergy effect in RCC cells and arrays. Protein expression profiles were screened via MS/TMT, revealing that FN3K was upregulated in the sunitinib group, and rescued in amiloride and the combination administration. Exogenous FN3K could promote proliferation, invasion and metastasis and decrease the sensitivity of Caki-1 cells to sunitinib, also, exogenous FN3K up-regulated VEGFR2 expression and activated AKT/mTOR signal pathway. More FN3K and VEGFR2 accumulated in R-Caki-1 cells and rescued by amiloride treatment. Co-IP and IF confirmed the interaction between FN3K and VEGFR2. In conclusion, FN3K depletion mediated VEGFR2 disruption promotes amiloride synergized the anti-RCC activity of sunitinib.
PubMed: 38868177
DOI: 10.1016/j.isci.2024.109997 -
Cell Biology and Toxicology Dec 2020Smoke inhalation injury is the leading cause of death in firefighters and victims. Inhaled hot air and toxic smoke are the predominant hazards to the respiratory...
Smoke inhalation injury is the leading cause of death in firefighters and victims. Inhaled hot air and toxic smoke are the predominant hazards to the respiratory epithelium. We aimed to analyze the effects of thermal stress and smoke aldehyde on the permeability of the airway epithelial barrier. Transepithelial resistance (R) and short-circuit current (I) of mouse tracheal epithelial monolayers were digitized by an Ussing chamber setup. Zonula occludens-1 tight junctions were visualized under confocal microscopy. A cell viability test and fluorescein isothiocyanate-dextran assay were performed. Thermal stress (40 °C) decreased R in a two-phase manner. Meanwhile, thermal stress increased I followed by its decline. Na depletion, amiloride (an inhibitor for epithelial Na channels [ENaCs]), ouabain (a blocker for Na/K-ATPase), and CFTRinh-172 (a blocker of cystic fibrosis transmembrane regulator [CFTR]) altered the responses of R and I to thermal stress. Steady-state 40 °C increased activity of ENaCs, Na/K-ATPase, and CFTR. Acrolein, one of the main oxidative unsaturated aldehydes in fire smoke, eliminated R and I. Na depletion, amiloride, ouabain, and CFTRinh-172 suppressed acrolein-sensitive I, but showed activating effects on acrolein-sensitive R. Thermal stress or acrolein disrupted zonula occludens-1 tight junctions, increased fluorescein isothiocyanate-dextran permeability but did not cause cell death or detachment. The synergistic effects of thermal stress and acrolein exacerbated the damage to monolayers. In conclusion, the paracellular pathway mediated by the tight junctions and the transcellular pathway mediated by active and passive ion transport pathways contribute to impairment of the airway epithelial barrier caused by thermal stress and acrolein. Graphical abstract Thermal stress and acrolein are two essential determinants for smoke inhalation injury, impairing airway epithelial barrier. Transcellular ion transport pathways via the ENaC, CFTR, and Na/K-ATPase are interrupted by both thermal stress and acrolein, one of the most potent smoke toxins. Heat and acrolein damage the integrity of the airway epithelium through suppressing and relocating the tight junctions.
Topics: Acrolein; Animals; Bronchi; Cells, Cultured; Cystic Fibrosis Transmembrane Conductance Regulator; Electric Impedance; Epithelial Cells; Epithelial Sodium Channels; Female; Hot Temperature; Humans; Inhalation Exposure; Ion Transport; Male; Membrane Transport Proteins; Mice, Inbred C57BL; Permeability; Smoke; Smoke Inhalation Injury; Sodium-Potassium-Exchanging ATPase; Tight Junctions; Trachea; Zonula Occludens-1 Protein
PubMed: 32588239
DOI: 10.1007/s10565-020-09545-1 -
Annals of Medicine and Surgery (2012) May 2021
PubMed: 33815782
DOI: 10.1016/j.amsu.2021.102261 -
American Journal of Physiology. Renal... Apr 2021Epithelial Na channel (ENaC) blockers elicit acute and substantial increases of urinary pH. The underlying mechanism remains to be understood. Here, we evaluated if...
Epithelial Na channel (ENaC) blockers elicit acute and substantial increases of urinary pH. The underlying mechanism remains to be understood. Here, we evaluated if benzamil-induced urine alkalization is mediated by an acute reduction in H secretion via renal H-K-ATPases (HKAs). Experiments were performed in vivo on HKA double-knockout and wild-type mice. Alterations in dietary K intake were used to change renal HKA and ENaC activity. The acute effects of benzamil (0.2 µg/g body wt, sufficient to block ENaC) on urine flow rate and urinary electrolyte and acid excretion were monitored in anesthetized, bladder-catheterized animals. We observed that benzamil acutely increased urinary pH (ΔpH: 0.33 ± 0.07) and reduced NH and titratable acid excretion and that these effects were distinctly enhanced in animals fed a low-K diet (ΔpH: 0.74 ± 0.12), a condition when ENaC activity is low. In contrast, benzamil did not affect urine acid excretion in animals kept on a high-K diet (i.e., during high ENaC activity). Thus, urine alkalization appeared completely uncoupled from ENaC function. The absence of benzamil-induced urinary alkalization in HKA double-knockout mice confirmed the direct involvement of these enzymes. The inhibitory effect of benzamil was also shown in vitro for the pig α-isoform of HKA. These results suggest a revised explanation of the benzamil effect on renal acid-base excretion. Considering the conditions used here, we suggest that it is caused by a direct inhibition of HKAs in the collecting duct and not by inhibition of the ENaC function. Bolus application of epithelial Na channel (EnaC) blockers causes marked and acute increases of urine pH. Here, we provide evidence that the underlying mechanism involves direct inhibition of the H-K pump in the collecting duct. This could provide a fundamental revision of the previously assumed mechanism that suggested a key role of ENaC inhibition in this response.
Topics: Amiloride; Animals; Epithelial Sodium Channels; H(+)-K(+)-Exchanging ATPase; Kidney Tubules, Collecting; Mice; Natriuresis; Renal Elimination; Sodium; Sodium, Dietary
PubMed: 33554781
DOI: 10.1152/ajprenal.00444.2020 -
Scientific Reports Aug 2022Long-term administration of lithium is associated with chronic interstitial fibrosis that is partially reduced with exposure to amiloride. We examined potential pathways...
Long-term administration of lithium is associated with chronic interstitial fibrosis that is partially reduced with exposure to amiloride. We examined potential pathways of how amiloride may reduce interstitial fibrosis. Amiloride was administered to a rat model of lithium induced interstitial fibrosis over a long term (6 months), as well as for short terms of 14 and 28 days. Kidney cortical tissue was subjected to RNA sequencing and microRNA expression analysis. Gene expression changes of interest were confirmed using immunohistochemistry on kidney tissue. Pathways identified by RNA sequencing of kidney tissue were related to 'promoting inflammation' for lithium and 'reducing inflammation' for amiloride. Validation of candidate genes found amiloride reduced inflammatory components induced by lithium including NF-κB/p65 and activated pAKT, and increased p53 mediated regulatory function through increased p21 in damaged tubular epithelial cells. Amiloride also reduced the amount of Notch1 positive PDGFrβ pericytes and infiltrating CD3 cells in the interstitium. Thus, amiloride attenuates a multitude of pro-inflammatory components induced by lithium. This suggests amiloride could be repurposed as a possible anti-inflammatory, anti-fibrotic agent to prevent or reduce the development of chronic interstitial fibrosis.
Topics: Amiloride; Animals; Fibrosis; Inflammation; Kidney; Lithium; Lung Diseases, Interstitial; Rats
PubMed: 36028651
DOI: 10.1038/s41598-022-18825-1 -
Journal of Nuclear Medicine : Official... Apr 2021Radium-223 dichloride ([Ra]RaCl2) is the first approved alpha particle-emitting therapy and is indicated for treatment of bone metastatic castrate resistant prostate...
Radium-223 dichloride ([Ra]RaCl2) is the first approved alpha particle-emitting therapy and is indicated for treatment of bone metastatic castrate resistant prostate cancer. Approximately half of the dose is absorbed into the gastrointestinal (GI) tract within minutes of administration, limiting disease-site uptake and contributing to toxicity. Here, we investigate the role of enteric ion channels and their modulation for improved therapeutic efficacy and reduced side effects. Utilizing primary human duodenal organoids (enteroids) as in vitro models of the functional GI epithelium, we found that Amiloride (ENaC blocker) and NS-1619 (K+ channel activator) presented significant effects in Ra membranal transport. The radioactive drug distribution was evaluated for lead combinations in vivo, and in osteosarcoma and prostate cancer models. Amiloride shifted Ra uptake in vivo from the gut, to nearly double the uptake at sites of bone remodeling. Bone tumor growth inhibition with the combination as measured by bioluminescent and X-ray imaging was significantly greater than single agents alone, and the combination resulted in no weight loss. This combination of approved agents may be readily implemented as a clinical approach to improve outcomes of bone metastatic cancer patients with the benefit of ameliorated tolerability.
PubMed: 33837069
DOI: 10.2967/jnumed.121.261977 -
Frontiers in Microbiology 2021One path toward identifying effective and easily accessible antifungals is to repurpose commonly used drugs. Amiloride, a widely used diuretic, inhibits different...
One path toward identifying effective and easily accessible antifungals is to repurpose commonly used drugs. Amiloride, a widely used diuretic, inhibits different isoforms of Na/H exchangers, Na channels, and Na/Ca exchangers. Here, we found that amiloride had poor antifungal activity against isolates of prompting the examination of the amiloride analog, HMA [5-(,-hexamethylene)amiloride]. HMA possesses strong activity against Na/H exchangers (NHEs) and little K-associated toxicity since HMA has only minimal inhibitory effects toward epithelial sodium channels (ENaC), the diuretic and antikaliuretic target of amiloride. Although HMA produced a robust dose-dependent growth inhibition of several fungal isolates, susceptibility assays revealed modest MICs against isolates of . A checkerboard dilution strategy resulted in fractional inhibitory concentrations (FIC) < 0.5, suggesting that HMA displays synergy with several antifungal azole drugs including posaconazole, voriconazole, and ketoconazole. Itraconazole and ravuconazole showed moderate synergy with HMA across all tested fungal isolates. In combination with HMA, ravuconazole had MICs of 0.004-0.008 μg/ml, a ∼16-fold reduction compared to MICs of ravuconazole when used alone and significantly more effective than the overall MIC (0.25 μg/ml) reported for ravuconazole against 541 clinical isolates of . In combination with azole drugs, MICs of HMA ranged from 3.2 μM (1 μg/ml) to 26 μM (16 μg/ml), HMA was not cytotoxic at concentrations ≤ 8 μg/ml, but MICs were above the reported HMA K of 0.013-2.4 μM for various Na/H exchangers. Our results suggest that HMA has limited potential as a monotherapy and may have additional targets in fungal/yeast cells since strains lacking NHEs remained sensitive to HMA. We determined that the hydrophobic substituent at the 5-amino group of HMA is likely responsible for the observed antifungal activity and synergy with several azoles since derivatives with bulky polar substitutions showed no activity against , indicating that other 5-substituted HMA derivatives could possess stronger antifungal activity. Moreover, substitution of other positions around the pyrazine core of HMA has not been investigated but could reveal new leads for antifungal drug development.
PubMed: 34025629
DOI: 10.3389/fmicb.2021.673035