The Adequacy and Compatibility of Compartmental Models of Electrolyte Exchange in the Dog's Heart

Abstract

The exchange of electrolytes (Na, K, SO₄) and albumin in the dog's heart was studied by using tracer technique in a modified heart-lung preparation. The data were analysed in order to investigate if the system could be characterized kinetically in terms of a few distinct compartments, and to what extent tracer measurements in systemic plasma and cardiac lymph provide information about the capillary and cellular exchange of electrolytes in the dog's heart. The compartmental models used for sodium and potassium were easily conformed so as to be compatible with the tracer data and it was also possible to make them consistent with independent relevant data from the literature. However, it was not possible to construct adequate models in the sense that the model parameters were well determined by the data. This was not due to inaccurate data but to the insufficiency of this type of data to identify adequate models of the required complexity. Therefore, detailed quantitative information on the electrolyte transport across cellular membranes cannot be obtained in experimental studies of the type presented in this investigation.