Factors that limit brain volume changes in response to acute and sustained hyper- and hyponatremia

摘要: Rats were made acutely hyper- or hyponatremic by infusion of hypertonic saline water, respectively. Other rats maintained in these states from 1 to 7 days observe the effects time. Brain tissue Na, Cl, and K compared with serum Na Cl concentration (Na(E) Cl(E)). The following observations are noted: content varies directly Cl(E) brain space (Na(e)) Na(E), indicating little no restraint on inward outward movement brain. intracellular volume fluid (V(i)) derived as difference between total water space, decreases hypernatremia increases hyponatremia. changes V(i) acute studies not accompanied any change content, calculated approximately 0.6 predicted osmotic behavior cells, which apply four assumptions: (a) Na(E) is proportional osmolality; (b) osmolality remains equal plasma (c) osmotically active; (d) there net gain loss solute V(i). validity assumptions considered. When sustained, much closer control values than when phase. can account for some adjustment observed over extended period regression (Na + K)/v upon describes a slope less 1.0 an intercept 40% K)/v. These characteristics interpreted mean that significant quantities inactive. protects itself response freedom move changing degree properties cells general, being With sustained osmolality, approaches normal part this later adjustment.