Binding of anions by connective tissue: dermis and cartilage

¹ Colleges of Dentistry, Pharmacy, and Medicine, University of Illinois Professional Colleges, Chicago, Illinois

Binding of various anions to dermis and cartilage was studied in vivo by a potentiometric method. The anions used were: fluoride, ascorbic acid, alizarin red S, the three isomeric dihydroxybenzoic acids, and succinic acid. By measuring colloidal charge in relation to pH, titration curves of connective tissue colloids were determined in normal states and in the presence of anions. Above the isoelectric point (pH 2.2–2.5) the negative charge is lowered. This was attributed to the binding of the anion, with a simultaneous uptake of protons. The magnitude of the effect depends on the nature of the anion and on the properties of the colloidal components. It is suggested that anions produced in metabolism may be bound to extracellular substances, thereby affecting the distribution of all other ions.