ENaC; uTPA; polycystin-2 (TRPP2)

Amiloride has an IC50 of 2.6 μM for blocking δβγ channels (58, 71, 75, 134, 148). Amiloride's Ki for δβγ ENaC channels is 26 times greater than that of αβγ channels (0.1 μM for αβγ ENaC). Compared to αβγ channels, amiloride's blockade of δβγ ENaC is more voltage-dependent. In contrast to the Ki values of αβη and δβγ channels, the amiloride Ki values for δαβγ channels are 920 and 13.7 μM at -120 and +80 mV, respectively [1]. Amiloride is an inhibitor of the epithelial sodium channel (ENaC) that is relatively selective. Its IC50, or the dose needed to cause 50% blockage of the ion channel, falls between 0.1 and 0.5 μM. With an IC50 as low as 3 μM in the presence of low external [Na+] and as high as 1 mM in the case of high [Na+], amiloride is a relatively weak inhibitor of the Na+/H+ exchanger (NHE). Amiloride has an IC50 of 1 mM, making it a weaker inhibitor of the Na+/Ca2+ exchanger (NCX). It is known that amiloride (1 μM) and submicromolar dosages of benzamil (30 nM) inhibit ENaC. This means that by preventing the ENaC protein from acting, they prevent the myogenic vasoconstrictive response to elevated perfusion pressure. In vascular smooth muscle cells (VSMC), amiloride totally blocks Na+ inflow at a dosage that is known to be relatively selective for ENaC (1.5 μM) [2].

In saline-drinking, stroke-prone spontaneously hypertensive rats (SHRSP) compared to controls, amiloride improved brain and kidney histological scores and reversed the initial increase in collagen deposition and prevented further increases in this tissue via subcutaneous injection (1 mg/kg/day) [2]. Amiloride also antagonizes or blocks the effects of aldosterone in these cells as well as in cardiovascular and renal tissue in animals with salt-dependent hypertension.

The MR and the ENaC have been demonstrated at the level of mRNA and at the protein level within fibroblasts, VSMC and endothelial cells. Kornel et al showed that VSMC from the aorta of rabbits treated with physiologic doses of aldosterone (5 nmol/L) for 7 to 10 days were found to have significant increases in Na+ influx. Furthermore, Na+ influx was almost completely inhibited by amiloride in doses known to be relatively specific for ENaC (1.5 μmol/L), but not by either the NHE-specific amiloride analogue ethylisopropyl-amiloride or the NCX-specific dichlorobenzamil. In a separate study, rabbits were treated with aldosterone (2 mg/day) for 4 weeks. Subsequently, VSMC were isolated from the aorta and quantification of Na+ channels was performed using ENaC specific [3H] amiloride binding. Aldosterone-treated animals had double the number of VSMC Na+ channels, suggesting a possible relationship between aldosterone and ENaC within VSMC.[2]

Campbell et al examined myocardial fibrosis in a high-salt/aldosterone state. Uninephrectomized Sprague-Dawley rats were placed on 1% NaCl drinking solution and given one of the following for 8 weeks: 1) aldosterone 0.75 μg/h subcutaneously; 2) amiloride 1 mg/kg/day subcutaneously; 3) aldosterone + amiloride subcutaneously; or 4) vehicle. Aldosterone increased BP significantly, an effect that was attenuated by amiloride. Microscopic scarring, a reparative fibrosis indicative of myocyte loss, was apparent in animals treated with aldosterone. However, when amiloride was given simultaneously with aldosterone, the microscopic scarring of both the left and right ventricles was completely prevented. The finding of scarring to the nonhypertensive right ventricle suggests that the benefits of amiloride were not from BP-lowering effects alone. The authors postulated that myocyte necrosis in hyperaldosteronism is likely a result of enhanced potassium excretion that can be prevented by amiloride. Although this remains a possibility, measurements of urinary Na+/K+handling and serum K+ were not performed. Furthermore, subsequent studies suggest other possible mechanisms of benefit (see later here).[2]

[1]. Ji, H.L., et al. delta ENaC: a novel divergent amiloride-inhibitable sodium channel. Am J Physiol Lung Cell Mol Physiol, 2012. 303(12): p. L1013-26.
[2]. Teiwes J, et al. Epithelial sodium channel inhibition in cardiovascular disease. A potential role for amiloride. Am J Hypertens. 2007 Jan;20(1):109-17.
[3]. Giamarchi A, et al. A polycystin-2 (TRPP2) dimerization domain essential for the function of heteromeric polycystin complexes. EMBO J. 2010 Apr 7;29(7):1176-91.

Amiloride is a member of the class of pyrazines resulting from the formal monoacylation of guanidine with the carboxy group of 3,5-diamino-6-chloropyrazine-2-carboxylic acid. It has a role as a sodium channel blocker and a diuretic. It is a member of pyrazines, an organochlorine compound, an aromatic amine and a member of guanidines. It is a conjugate base of an amiloride(1+).
A pyrazine compound inhibiting sodium reabsorption through sodium channels in renal epithelial cells. This inhibition creates a negative potential in the luminal membranes of principal cells, located in the distal convoluted tubule and collecting duct. Negative potential reduces secretion of potassium and hydrogen ions. Amiloride is used in conjunction with diuretics to spare potassium loss. (From Gilman et al., Goodman and Gilman's The Pharmacological Basis of Therapeutics, 9th ed, p705)
Amiloride is a Potassium-sparing Diuretic. The physiologic effect of amiloride is by means of Decreased Renal K+ Excretion, and Increased Diuresis.

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Amiloride is a potassium-sparing diuretic used in the therapy of edema often in combination with thiazide diuretics. Amiloride has been linked to rare cases of clinically apparent drug induced liver disease.
Amiloride is a synthetic pyrazine derivative with antikaliuretic and diuretic properties. Amiloride inhibits sodium channels located in the distal tubules and collecting ducts of the kidney, thereby preventing the absorption of sodium and increasing its excretion along with water, to produce naturesis. In response to the hypernatremic conditions in the kidney, the plasma membrane becomes hyperpolarized and electrochemical forces are reduced, which then prevents the excretion of potassium and hydrogen into the lumen.
A pyrazine compound inhibiting SODIUM reabsorption through SODIUM CHANNELS in renal EPITHELIAL CELLS. This inhibition creates a negative potential in the luminal membranes of principal cells, located in the distal convoluted tubule and collecting duct. Negative potential reduces secretion of potassium and hydrogen ions. Amiloride is used in conjunction with DIURETICS to spare POTASSIUM loss. (From Gilman et al., Goodman and Gilman's The Pharmacological Basis of Therapeutics, 9th ed, p705)

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Amiloride, an antikaliuretic-diuretic agent, is a pyrazine-carbonyl-guanidine that is unrelated chemically to other known antikaliuretic or diuretic agents. It is an antihypertensive, potassium-sparing diuretic that was first approved for use in 1967 and helps to treat hypertension and congestive heart failure. The drug is often used in conjunction with thiazide or loop diuretics. Due to its potassium-sparing capacities, hyperkalemia (high blood potassium levels) are occasionally observed in patients taking amiloride. The risk is high in concurrent use of ACE inhibitors or spironolactone. Patients are also advised not to use potassium-containing salt replacements.

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Amiloride works by inhibiting sodium reabsorption in the distal convoluted tubules and collecting ducts in the kidneys by binding to the amiloride-sensitive sodium channels. This promotes the loss of sodium and water from the body, but without depleting potassium. Amiloride exerts its potassium sparing effect through the inhibition of sodium reabsorption at the distal convoluted tubule, cortical collecting tubule and collecting duct; this decreases the net negative potential of the tubular lumen and reduces both potassium and hydrogen secretion and their subsequent excretion. Amiloride is not an aldosterone antagonist and its effects are seen even in the absence of aldosterone.

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Readily absorbed following oral administration. Plasma half-life varies from 6 to 9 hours.

C6H8CLN7O

229.63

229.0479

C, 31.38; H, 3.51; Cl, 15.44; N, 42.70; O, 6.97

2609-46-3

Amiloride hydrochloride;2016-88-8;Amiloride hydrochloride dihydrate;17440-83-4

16231

Typically exists as Off-white to light yellow solids at room temperature

2.11g/cm3

628.1ºC at 760 mmHg

333.7ºC

1.08E-15mmHg at 25°C

1.884

1.27

156.79

O=C(C1=NC(Cl)=C(N)N=C1N)NC(N)=N

XSDQTOBWRPYKKA-UHFFFAOYSA-N

InChI=1S/C6H8ClN7O/c7-2-4(9)13-3(8)1(12-2)5(15)14-6(10)11/h(H4,8,9,13)(H4,10,11,14,15)

3,5-diamino-6-chloro-N-(diaminomethylidene)pyrazine-2-carboxamide

MK-870; MK 870; Amipramidin; Guanamprazin; Guanamprazine; Amipramizid; Midamor; Amilorida; MK870

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)