Furosemide

Furosemide is a loop diuretic that blocks sodium and chloride reabsorption in the kidney’s loop of Henle, increasing urine production. It is used to treat fluid retention and, in some cases, high blood pressure.

Na-K-2Cl cotransporter: A membrane protein that transports sodium, potassium, and chloride together across cell membranes. Furosemide inhibits this transporter in the thick ascending limb of the loop of Henle.
Edema: Swelling caused by excess fluid trapped in the body's tissues. Furosemide reduces excess fluid in conditions such as heart, kidney, and liver disease.
Thiazide diuretic: A diuretic that inhibits sodium-chloride transport in the kidney's distal convoluted tubule. Thiazides act farther along the nephron and generally produce less diuresis than loop diuretics.
Nephron: The kidney's microscopic functional unit, which filters blood and modifies filtrate to form urine. Furosemide changes salt handling within a specific segment of this unit.
Loop of Henle: A U-shaped section of a kidney nephron that helps establish the concentration gradient needed to regulate urine. Furosemide acts in its thick ascending limb, where much filtered salt is normally reclaimed.
Heart failure: A condition in which the heart cannot pump enough blood to meet the body's needs. Reducing congestion and fluid overload is a common reason to prescribe furosemide.
Spironolactone: A potassium-sparing diuretic that blocks aldosterone receptors in the distal nephron. Unlike furosemide, it tends to retain potassium and is often paired with it in ascites treatment.
Glomerular filtration: The movement of water and small solutes from blood into kidney nephron tubules. Furosemide acts on filtered fluid after it enters the nephron.
Diuretic: A substance that increases urine production, typically by reducing kidney reabsorption of water or dissolved substances. Furosemide is a potent member of this broader drug class.
Pulmonary edema: Excess fluid in the lungs that can cause severe shortness of breath. Intravenous furosemide may be used to relieve fluid overload in selected cases.

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