Nascimento L, Rademacher D R, Hamburger R, Arruda J A, Kurtzman A
J Lab Clin Med. 1977 Mar;89(3):455-62.
The effect of lithium chloride administration on urinary acidification was studied in dogs. Lithium-treated dogs developed hyperchloremic metabolic acidosis with alkaline urine. Bicarbonate loading resulted in a normal increase in urinary Pco2 in normal dogs but failed to produce the same response in lithium-treated dogs. The bicarbonate titration curve of lithium-treated dogs revealed a small leak of bicarbonate at low plasma levels of bicarbonate; at high plasma levels bicarbonate reabsorption was significantly higher in lithium-treated dogs. This pattern of bicarbonate reabsorption is identical to that described in classic distal renal tubular acidosis. Sodium sulfate administration resulted in a normal urinary acidification ilithium-treated dogs. It is possible that lithium administration induces distal renal tubular acidosis by allowing excessive back-diffusion of acid. This excessive back-diffusion of acid would result in a low urinary Pco2 during bicarbonate loading. Sodium sulfate administration, by increasing the negative intratubular potential, would restrict back-diffusion of hydrogen ion and thereby result in a normal acidification in lithium-treated dogs. We previously demonstrated that postureteral obstruction of the kidney fails to increase urinary Pco2 during bicarbonate loading and to lower urinary pH with sodium sulfate. It is possible that a low urinary Pco2 during HCO3 loading can occur as a consequence of either diminished hydrogen ion secretion (postobstructed kidney) or excessive back-diffusion of acid (lithium administration). Further studies are indicated to determine whether both mechanisms may be found in patients with distal renal tubular acidosis.
研究了氯化锂给药对犬尿液酸化的影响。接受锂治疗的犬出现高氯性代谢性酸中毒且尿液呈碱性。给予碳酸氢盐后，正常犬尿液Pco₂正常升高，但接受锂治疗的犬未产生相同反应。接受锂治疗的犬的碳酸氢盐滴定曲线显示，在血浆碳酸氢盐水平较低时，碳酸氢盐有少量泄漏；在血浆水平较高时，接受锂治疗的犬的碳酸氢盐重吸收明显更高。这种碳酸氢盐重吸收模式与经典远端肾小管酸中毒中描述的模式相同。给予硫酸钠后，接受锂治疗的犬尿液酸化正常。锂给药可能通过允许酸过度反向扩散而诱发远端肾小管酸中毒。这种酸的过度反向扩散会导致给予碳酸氢盐期间尿液Pco₂降低。给予硫酸钠通过增加肾小管内负电位，会限制氢离子的反向扩散，从而导致接受锂治疗的犬尿液酸化正常。我们之前证明，肾脏输尿管梗阻在给予碳酸氢盐期间不会增加尿液Pco₂，用硫酸钠也不会降低尿液pH。在给予HCO₃期间尿液Pco₂较低可能是由于氢离子分泌减少（梗阻后肾脏）或酸的过度反向扩散（锂给药）所致。需要进一步研究以确定在远端肾小管酸中毒患者中是否可能发现这两种机制。
