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The epithelial sodium channel (ENaC), (also known as amiloride-sensitive sodium channel) is a membrane-bound ion channel that is selectively permeable to sodium ions (Na +).It is assembled as a heterotrimer composed of three homologous subunits α or δ, β, and γ, [2] These subunits are encoded by four genes: SCNN1A, SCNN1B, SCNN1G, and SCNN1D.
Aldosterone is the main mineralocorticoid steroid hormone produced by the zona glomerulosa of the adrenal cortex in the adrenal gland. [4] [5] It is essential for sodium conservation in the kidney, salivary glands, sweat glands, and colon. [6]
The mineralocorticoid receptor (or MR, MLR, MCR), also known as the aldosterone receptor or nuclear receptor subfamily 3, group C, member 2, (NR3C2) is a protein that in humans is encoded by the NR3C2 gene that is located on chromosome 4q31.1-31.2. [5] MR is a receptor with equal affinity for mineralocorticoids and glucocorticoids.
In Liddle's syndrome, ENaC-binding potassium-sparing diuretics (e.g. amiloride or triamterene) are used to counter the excess ENaC activity. [ 4 ] [ 10 ] [ 2 ] In AME, the mineralocorticoid receptor-binding potassium-sparing diuretics (e.g. spironolactone or eplerenone ) are used to limit aldosterone receptor activity . [ 1 ]
The inactivating mutation leads to elevated local concentrations of cortisol in the aldosterone sensitive tissues like the kidney. Cortisol at high concentrations can cross-react and activate the mineralocorticoid receptor due to the non-selectivity of the receptor, leading to aldosterone-like effects in the kidney.
In physiology, aldosterone escape is a term that has been used to refer to two distinct phenomena involving aldosterone that are exactly opposite each other: Escape from the sodium -retaining effects of excess aldosterone (or other mineralocorticoids ) in primary hyperaldosteronism , manifested by volume and/or pressure natriuresis .
A mineralocorticoid receptor antagonist (MRA or MCRA) [1] or aldosterone antagonist, is a diuretic drug which antagonizes the action of aldosterone at mineralocorticoid receptors. This group of drugs is often used as adjunctive therapy, in combination with other drugs, for the management of chronic heart failure .
It selectively stimulates secretion of aldosterone. The secretion of aldosterone has a diurnal rhythm. Control of aldosterone release from the adrenal cortex: [citation needed] The role of the renin–angiotensin system: Angiotensin is involved in regulating aldosterone and is the core regulator. Angiotensin II acts synergistically with potassium.