Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
Department of Surgical Sciences, anesthesiology and Intensive Care, Uppsala University, Uppsala, Sweden.
Physiol Rep. 2023 Nov;11(22):e15886. doi: 10.14814/phy2.15886.
Perioperative hyponatremia, due to non-osmotic release of the antidiuretic hormone arginine vasopressin, is a serious electrolyte disorder observed in connection with many types of surgery. Since blood loss during surgery contributes to the pathogenesis of hyponatremia, we explored the effect of bleeding on plasma sodium using a controlled hypotensive hemorrhage pig model. After 30-min baseline period, hemorrhage was induced by aspiration of blood during 30 min at mean arterial pressure <50 mmHg. Thereafter, the animals were resuscitated with retransfused blood and a near-isotonic balanced crystalloid solution and monitored for 180 min. Electrolyte and water balances, cardiovascular response, renal hemodynamics, and markers of volume regulation and osmoregulation were investigated. All pigs (n = 10) developed hyponatremia. All animals retained hypotonic fluid, and none could excrete net-free water. Urinary excretion of aquaporin 2, a surrogate marker of collecting duct responsiveness to antidiuretic hormone, was significantly reduced at the end of the study, whereas lysine vasopressin, i.e., the pig antidiuretic hormone remained high. In this animal model, hyponatremia developed due to net positive fluid balance and generation of electrolyte-free water by the kidneys. A decreased urinary aquaporin 2 excretion may indicate an escape from antidiuresis.
围手术期低钠血症是一种严重的电解质紊乱，与多种类型的手术有关，其病因是抗利尿激素精氨酸血管加压素非渗透性释放。由于术中失血会导致低钠血症的发病机制，我们使用控制性降压出血猪模型来研究出血对血浆钠的影响。在 30 分钟的基线期后，通过在平均动脉压<50mmHg 下抽吸血液 30 分钟来诱导出血。此后，动物通过回输血液和接近等渗平衡晶体溶液进行复苏，并监测 180 分钟。研究了电解质和水的平衡、心血管反应、肾血液动力学以及容量调节和渗透压调节的标志物。所有猪（n=10）均出现低钠血症。所有动物均保留低渗液体，且均无法排出净自由水。在研究结束时，作为集合管对抗利尿激素反应的替代标志物的水通道蛋白 2 的尿排泄显著减少，而赖氨酸血管加压素（即猪抗利尿激素）仍保持高水平。在这种动物模型中，低钠血症的发生是由于净正液体平衡和肾脏产生无电解质水。尿中水通道蛋白 2 排泄减少可能表明抗利尿作用减弱。
