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一、钾代谢概述 (一)体内钾的分布 成人体内含钾总量为140克,约为50mmol/kg,主要存于细胞内,占总钾的98％。细胞内钾浓度为140～150mmol/L,3/4在肌细胞内。细胞外液中钾仅占2％,而血浆中只占0.4％。细胞外液中钾浓度为3.5～5.0mmol/L,主要以离子状态存在;而细胞内钾的2/3与蛋白质,糖或磷酸相结合。钾能透过细胞膜,但是细胞内外钾浓度相差很大,已证明维持此梯度的是Na±K~+/ATP酶 (二)钾的吸收与排泄 人体内钾主要来自食物,正常每天饮食内含钾70～100mmol,1mmol/kg,多在小肠吸收。摄入的钾参于体内细胞代谢后主要由肾排出,占90％每天约20～60mm-
First, an overview of potassium metabolism (A) the distribution of potassium in vivo The total body potassium in adults is 140 grams, about 50mmol / kg, mainly in the cells, accounting for 98% of the total potassium. Intracellular potassium concentration of 140 ~ 150mmol / L, 3/4 in muscle cells. Extracellular potassium in only 2%, while only 0.4% of plasma. Extracellular potassium concentration of 3.5 ~ 5.0mmol / L, mainly in the ionic state; and intracellular potassium 2/3 and protein, sugar or phosphoric acid combination. Potassium can penetrate the cell membrane, but the intracellular and extracellular potassium concentrations vary widely. It has been shown that the maintenance of this gradient is Na ± K ~ + / ATPase. (2) Potassium absorption and excretion Potassium in human is mainly from food, Potassium 70 ~ 100mmol, 1mmol / kg, more absorption in the small intestine. Potassium intake in vivo metabolism of cells mainly by renal excretion, accounting for 90% of about 20 ~ 60mm-