Quantitative interrelationship between Gibbs-Donnan equilibrium, osmolality of body fluid compartments, and plasma water sodium concentration

Abstract

The presence of negatively charged, impermeant proteins in the plasma space alters the distribution of diffusible ions in the plasma and interstitial fluid (ISF) compartments to preserve electroneutrality. We have derived a new mathematical model to define the quantitative interrelationship between the Gibbs-Donnan equilibrium, the osmolality of body fluid compartments, and the plasma water Na+ concentration ([Na+]pw) and validated the model using empirical data from the literature. The new model can account for the alterations in all ionic concentrations (Na+ and non-Na+ ions) between the plasma and ISF due to Gibbs-Donnan equilibrium. In addition to the effect of Gibbs-Donnan equilibrium on Na+ distribution between plasma and ISF, our model predicts that the altered distribution of osmotically active non-Na+ ions will also have a modulating effect on the [Na+]pw by affecting the distribution of H2O between the plasma and ISF. The new physiological insights provided by this model can for the first time provide a basis for understanding quantitatively how changes in the plasma protein concentration modulate the [Na+]pw. Moreover, this model defines all known physiological factors that may modulate the [Na+]pw and is especially helpful in conceptually understanding the pathophysiological basis of the dysnatremias.

Characterization of the Ionic Profile of the Extracellular Space of the Injured and Ischemic Brain: A Microdialysis Study

“…Under these circumstances, a set of possible speculative options to explain these findings are: 1) patients could be treated with HTS and have an increase in [Na + ] o as a consequence of high plasma Na + levels (this was not the case in our series where patients with [Na + ] o > 162 mmol/L had [Na + ] serum within the normal range); 2) proteins released from dying cells and particularly DNA-histone complexes might release Na + ; 42 3) an increase in the negatively charged protein concentration in the TC attracts positively charged Na + ions into the core, thereby leading to an increase in the [Na + ] o ; 4) the preload of cells with Na + in the early phases of injury due to cytotoxic edema can release a higher [Na + ] i into the necrotic tissue; and 5) the increased activity of Na + /H + exchangers in the traumatic penumbra may release Na + into the core that will act as an inert sink. The role of Na + /H + exchangers and other sodium transporters in ischemia has been discussed by O'Donnell in a recent review.…”

Serum Sodium Levels and Patient Outcomes in an Ambulatory Clinic-Based Chronic Kidney Disease Cohort

“…Lower eGFR was a predictor of higher serum Na + analyzed as a continuous variable in both baseline and time-dependent models, although the association with lower eGFR was not significant with hypernatremia as a category. For maintaining electroneutrality, through the Gibbs-Donnan effect, an increment in the negatively charged albumin levels attracts positively charged sodium ion into the plasma, thereby leading to increasing Na + concentration [46]. In our cohort, CKD patients with hyponatremia were more likely to have higher BUN.…”

Collagen intrafibrillar mineralization as a result of the balance between osmotic equilibrium and electroneutrality

“…those not involved in counterion condensation) and salt ions (Na + , Cl − ) present in the mineralising solution 33 . Establishment of Gibbs-Donnan equilibrium 35 between the intrafibrillar and extrafibrillar water compartments of collagen represents a means of providing the long-ranged interactions for ACP to infiltrate into fibrillar collagen (Fig. SI-11B).…”