4. K + Na + ATPase K + H + K + channel 140-160 mmol/L 4.2±0.3mmol/L 50-200mmol/day K + ingestion Kidney colon skin (90%) insulin β-adrenergic agonist ECF [K + ] K + : 50-55mmol/kg B.W toxin (Ba) acid-base state Pump-leak
5. ① free filtration ② reabsorption (90% of filtered potassium) ③ secretion or reabsorption (in normal diet, secretion is major) K + K + K + Proximal tubule &Henle’s loop Distal tubule & Collecting duct
6. Three elements for achieving potassium secretion: 1. Na + -K + -ATPase on basolateral membrane 2. Permeability of luminal membrane to K+ 3. Electrochemical gradient from blood to tubular lumen ATPase Na + K + K + channel K + Principal cell Basolateral membrane luminal membrane peritubular interstitial tubular lumen K +
7.
8. K + Na + ATPase K + H + K + channel 140-160 mmol/L 4.2±0.3mmol/L 50-200mmol K + ingestion Kidney colon skin (90%) insulin β-adrenergic agonist ECF [K + ] 50-55mmol/kg B.W ADS ECF K + concentration Urinary flow rate acid-base state toxin drug acid-base state