Model connective tissue system: The effect of proteoglycans on the distribution of small non‐electrolytes and micro‐ions

Donnan equilibria between solutions of various carbohydrates polyins and Na ⊕ have been measured by equilibrium dialysis. From the results, estimates have been made of the degree of Na ⊕ fixation by the polyions. Comparison is made between the behavior of the complex proteoglycan macromolecules and their constituent glycosaminoglycans. Attempts to interpret these results and the Na ⊕ activity in saltfree solutions on the parameter of the intercharge distance has been made. By use of studies on carboxymethylcellulose, the relative importance of the carboxyl and of the sulphate ester groups in the Na ⊕ fixation is assessed. The relevance of the measurements to the previously described diffusional effects found in real and model connective tissues is discussed.