【正文】 AP 60mv TP(Et) 90mv RP(Em) hyperpolarization (2). Heart arrhythmia 0 mv serum[K+] 30mv 60mv 90mv depolarization Excitability: [K+]ECF K+ permeability depolarization repolarization excitability ECG T wave Conductivity: RP 0 phase of AP conductivity conductive block unidirectional block ECG PR Autorhythmicity: Contractility: acute 。 chronic effects on heart cardiac excitability ↑ cardiac conductivity ↓ cardiac automaticity ↑ cardiac contractibility ↑ → ↓ (3). Renal polyuria (sensitivity of ADH ) (4). GI smooth muscles Hyperpolarization (5). acidbase balance metabolic alkalosis paradoxical aciduria 4. principles of prevention and treatment of primary disease of potassium pensation oral application is better Give potassium according to the urine concentration ? 40mmol/L， slowly 1020mmol/h to observe： heart rate cardiac rhythm consciousness acid base 1. definition : hyperkalemia is defined as serum potassium exceeding Ⅲ . hyperkalemia 2. causes (1). increased intake of potassium (2). Impaired renal potassium excretion ： ① renal dysfunction ② ALD ↓ ③ potassiumsparing diuretics (3). abnormal potassium transcellular ditribution ① acute acidosis ② hypoxia→ ATP ↓ ③ tissue damage ④ hyperkalemic periodic paralysis ⑤ Diabetes ⑥ Betareceptor inhibbitor 3. alterations of metabolism and function (1).effect on neuromuscular excitability: (2).effects on heart cardiac excitability ↑ → ↓ cardiac conductivity ↓ cardiac automaticity ↓ cardiac contractibility ↓ (3).effect on the acidbase balance acidosis paradoxical alkaline urine skeletal muscle ＜ 8mmol/L RP (depolarization) excitability stabbing。 tremor ＞ 8mmol/L RP inactivation of Na+ channel depolarization paralysis heart (hyperkalemia K+ permeability ) → RP → E excitability 79mmol/L→ RP → E T wave 。 QT short cardiac arrest PR QT Autorhythmicity: K+ out ward of phase 4 Spontaneous depolarization heart rate Conductivity: RP Na+ inward of phase 0 conductivity conductive block unidirectional block Contractility : inhibition of Ca2+ inward flow contractility acidbase balance ? acidosis ? paradoxical alkaline urine 4. principles of prevention and treatment a) treatment of primary disease b) decrease uptake of K+ c) cut down total amount of body potassium dialysis ionexchange resin d) induce K+ uptake by cells. e) application