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|Section2= |Section6= |Section7= }} Aldosterone is a steroid hormone (mineralocorticoid family) produced by the outer section (zona glomerulosa) of the adrenal cortex in the adrenal gland.〔Marieb Human Anatomy & Physiology 9th edition, chapter:16, page:629, question number:14〕 It plays a central role in the regulation of blood pressure mainly by acting on the distal tubules and collecting ducts of the nephron, increasing reabsorption of ions and water in the kidney, to cause the conservation of sodium, secretion of potassium, increase in water retention, and increase in blood pressure and blood volume.〔 When dysregulated, aldosterone is pathogenic and contributes to the development and progression of cardiovascular and renal disease.〔 Aldosterone has exactly the opposite function of the atrial natriuretic hormone secreted by the heart.〔 Aldosterone is part of the renin–angiotensin system. Drugs that interfere with the secretion or action of aldosterone are in use as antihypertensives, like lisinopril, which lowers blood pressure by blocking the angiotensin-converting enzyme (ACE), leading to lower aldosterone secretion. The net effect of these drugs is to reduce sodium and water retention but increase retention of potassium. Another example is spironolactone, a potassium-sparing diuretic, which decreases blood pressure by releasing fluid from the body while retaining potassium. It was first isolated by Simpson and Tait in 1953. ==Synthesis== The corticosteroids are synthesized from cholesterol within the zona glomerulosa of adrenal cortex. Most steroidogenic reactions are catalysed by enzymes of the cytochrome P450 family. They are located within the mitochondria and require adrenodoxin as a cofactor (except 21-hydroxylase and 17α-hydroxylase). Aldosterone and corticosterone share the first part of their biosynthetic pathways. The last parts are mediated either by the aldosterone synthase (for aldosterone) or by the 11β-hydroxylase (for corticosterone). These enzymes are nearly identical (they share 11β-hydroxylation and 18-hydroxylation functions), but aldosterone synthase is also able to perform an 18-oxidation. Moreover, aldosterone synthase is found within the zona glomerulosa at the outer edge of the adrenal cortex; 11β-hydroxylase is found in the zona glomerulosa and zona fasciculata. Note: aldosterone synthase is absent in other sections of the adrenal gland. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「aldosterone」の詳細全文を読む スポンサード リンク
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