Melton J E, Nattie E E
Am J Physiol. 1983 May;244(5):R724-32. doi: 10.1152/ajpregu.1983.244.5.R724.
Dilutional (DH) and isosmotic (IH) hyponatremia (plasma [Na+] = 103-109 meq/l) were produced in conscious rats over 3-6 h by intraperitoneal injection of water or mannitol Ringer solution. During DH, CSF [Na+], [Cl-], and osmolality decreased as predicted by passive dilution by the water load. During IH, these variables exhibited little change. Brain water was unchanged during IH despite significant reduction of brain Na+ and Cl- content suggesting that tissue ions lost were replaced by other osmoles. During DH, brain water increased but less than predicted by passive osmotic equilibration. Cell volume increased as predicted by passive swelling while the extracellular volume (Cl space) decreased. Tissue K+ content decreased by a small but significant amount. Tissue Na+ and Cl- decreased by 21 and 28%. This pattern of fluid compartmental and electrolyte changes suggests that brain volume regulation during acute DH occurs via reduction of extracellular volume as cells swell. This may result from bulk flow of extracellular fluid to CSF or from ion and water movement across the blood-brain barrier.
通过腹腔注射水或甘露醇林格液，在3 - 6小时内使清醒大鼠产生稀释性（DH）和等渗性（IH）低钠血症（血浆[Na⁺]=103 - 109 meq/l）。在DH期间，脑脊液[Na⁺]、[Cl⁻]和渗透压如因水负荷被动稀释所预测的那样降低。在IH期间，这些变量变化很小。在IH期间，尽管脑Na⁺和Cl⁻含量显著降低，但脑含水量未变，这表明丢失的组织离子被其他渗透溶质所替代。在DH期间，脑含水量增加，但低于被动渗透平衡所预测的增加量。细胞体积如被动肿胀所预测的那样增加，而细胞外体积（Cl空间）减小。组织K⁺含量有少量但显著的降低。组织Na⁺和Cl⁻分别降低了21%和28%。这种体液分隔和电解质变化模式表明，急性DH期间脑体积调节是通过细胞肿胀时细胞外体积的减少来实现的。这可能是由于细胞外液向脑脊液的大量流动，或者是离子和水跨血脑屏障的移动所致。
