Kinetic Modeling of Intracellular pH and Comparison with 31 P NMR Experimental Values in Dialysed Uremic Patients

Changes in intra-erythrocytic pH values over time, during and after bicarbonate hemodialysis, were studied with ³¹P Nuclear Magnetic Resonance. Simultaneously, pH values of whole blood were obtained by a gazometric method. A two-compartment model appeared to be the simplest kinetic model to explain the shifts in proton concentrations in extra- and intracellular media. Non-linear regression was used to determine exchange constant values. There was a very good correlation between the experimental and calculated proton concentrations. This model can describe all patients but individual experimental constants must be determined. Under these conditions a single blood pH determination before dialysis will permit determination of the initial intra-erythrocytic pH and monitoring of intra-erythrocytic pH during hemodialysis.