The collecting duct system of the kidney consists of a series of tubules and ducts that physically connect nephrons to a minor calyx or directly to the renal pelvis. The collecting duct system is the last part of nephron and participates in electrolyte and fluid balance through reabsorption and excretion, processes regulated by the hormones aldosterone and vasopressin.
Amiloride, sold under the trade name Midamor among others, is a medication typically used with other medications to treat high blood pressure or swelling due to heart failure or cirrhosis of the liver. Amiloride is classified as a potassium-sparing diuretic. Amiloride is often used together with another diuretic, such as a thiazide or loop diuretic. It is taken by mouth. Onset of action is about two hours and it lasts for about a day.
Cystic fibrosis transmembrane conductance regulator (CFTR) is a membrane protein and chloride channel in vertebrates that is encoded by the CFTR gene.
Potassium-sparing diuretics refers to drugs that cause diuresis without causing potassium loss in the urine. They are typically used as an adjunct in management of hypertension, cirrhosis, and congestive heart failure. The steroidal aldosterone antagonists can also be used for treatment of primary hyperaldosteronism. Spironolactone, a steroidal aldosterone antagonist, is also used in management of female hirsutism and acne from PCOS or other causes.
Liddle's syndrome, also called Liddle syndrome, is a genetic disorder inherited in an autosomal dominant manner that is characterized by early, and frequently severe, high blood pressure associated with low plasma renin activity, metabolic alkalosis, low blood potassium, and normal to low levels of aldosterone. Liddle syndrome involves abnormal kidney function, with excess reabsorption of sodium and loss of potassium from the renal tubule, and is treated with a combination of low sodium diet and potassium-sparing diuretics. It is extremely rare, with fewer than 30 pedigrees or isolated cases having been reported worldwide as of 2008.
The epithelial sodium channel is a membrane-bound ion channel that is selectively permeable to the ions of sodium and that is assembled as a heterotrimer composed of three homologous subunits α or δ, β, and γ, These subunits are encoded by four genes: SCNN1A, SCNN1B, SCNN1G, and SCNN1D. It is involved primarily in the reabsorption of sodium ions at the collecting ducts of the kidney's nephrons. In addition to being implicated in diseases where fluid balance across epithelial membranes is perturbed, including pulmonary edema, cystic fibrosis, COPD and COVID-19, proteolyzed forms of ENaC function as the human salt taste receptor.
Eccrine sweat glands are the major sweat glands of the human body, found in virtually all skin, with the highest density in palm and soles, then on the head, but much less on the torso and the extremities. In other mammals, they are relatively sparse, being found mainly on hairless areas such as foot pads. They reach their peak of development in humans, where they may number 200–400/cm2 of skin surface. They produce a clear, odorless substance, sweat, consisting primarily of water. These are present from birth. Their secretory part is present deep inside the dermis.
Neural precursor cell expressed developmentally downregulated gene 4-like (NEDD4L) or NEDD4-2 is an enzyme of the NEDD4 family. In human the protein is encoded by the NEDD4L gene. In mouse the protein is commonly known as NEDD4-2 and the gene Nedd4-2.
The SCNN1B gene encodes for the β subunit of the epithelial sodium channel ENaC in vertebrates. ENaC is assembled as a heterotrimer composed of three homologous subunits α, β, and γ or δ, β, and γ. The other ENAC subunits are encoded by SCNN1A, SCNN1G, and SCNN1D.
The SCNN1A gene encodes for the α subunit of the epithelial sodium channel ENaC in vertebrates. ENaC is assembled as a heterotrimer composed of three homologous subunits α, β, and γ or δ, β, and γ. The other ENAC subunits are encoded by SCNN1B, SCNN1G, and SCNN1D.
The SCNN1G gene encodes for the γ subunit of the epithelial sodium channel ENaC in vertebrates. ENaC is assembled as a heterotrimer composed of three homologous subunits α, β, and γ or δ, β, and γ. The other ENAC subunits are encoded by SCNN1A, SCNN1B, and SCNN1D.
Acid-sensing ion channel 1 (ASIC1) also known as amiloride-sensitive cation channel 2, neuronal (ACCN2) or brain sodium channel 2 (BNaC2) is a protein that in humans is encoded by the ASIC1 gene. The ASIC1 gene is one of the five paralogous genes that encode proteins that form trimeric acid-sensing ion channels (ASICs) in mammals. The cDNA of this gene was first cloned in 1996. The ASIC genes have splicing variants that encode different proteins that are called isoforms.
Prostasin is a protein that in humans is encoded by the PRSS8 gene.
Acid-sensing ion channel 3 (ASIC3) also known as amiloride-sensitive cation channel 3 (ACCN3) or testis sodium channel 1 (TNaC1) is a protein that in humans is encoded by the ASIC3 gene. The ASIC3 gene is one of the five paralogous genes that encode proteins that form trimeric acid-sensing ion channels (ASICs) in mammals. The cDNA of this gene was first cloned in 1998. The ASIC genes have splicing variants that encode different proteins that are called isoforms.
Acid-sensing ion channel 2 (ASIC2) also known as amiloride-sensitive cation channel 1, neuronal (ACCN1) or brain sodium channel 1 (BNaC1) is a protein that in humans is encoded by the ASIC2 gene. The ASIC2 gene is one of the five paralogous genes that encode proteins that form trimeric acid-sensing ion channels (ASICs) in mammals. The cDNA of this gene was first cloned in 1996. The ASIC genes have splicing variants that encode different proteins that are called isoforms.
The SCNN1D gene encodes for the δ (delta) subunit of the epithelial sodium channel ENaC in vertebrates. ENaC is assembled as a heterotrimer composed of three homologous subunits α, β, and γ or δ, β, and γ. The other ENAC subunits are encoded by SCNN1A, SCNN1B, and SCNN1G.
Sodium channel blockers are drugs which impair the conduction of sodium ions (Na+) through sodium channels.
A channel blocker is the biological mechanism in which a particular molecule is used to prevent the opening of ion channels in order to produce a physiological response in a cell. Channel blocking is conducted by different types of molecules, such as cations, anions, amino acids, and other chemicals. These blockers act as ion channel antagonists, preventing the response that is normally provided by the opening of the channel.
Transepithelial potential difference (TEPD) is the voltage across an epithelium, and is the sum of the membrane potentials for the outer and inner cell membranes.
Elexacaftor/tezacaftor/ivacaftor, sold under the brand names Trikafta (US) and Kaftrio (EU), is a fixed-dose combination medication used to treat cystic fibrosis. Elexacaftor/tezacaftor/ivacaftor is composed of a combination of ivacaftor, a chloride channel opener, and elexacaftor and tezacaftor, CFTR modulators.
