title: Adsorption of glycosaminoglycans to the cell surface is responsible for cellular donnan effects.
abstract: In previous publications, we showed that extracellular glycosaminoglycans reduced the membrane potential, caused cell blebbing and swelling and decreased the intracellular pH independently of cell surface receptors. These phenomena were explained by Donnan effects. The effects were so large that they could not be attributed to glycosaminoglycans in solution. Therefore, we tested the hypothesis that glycosaminoglycans were concentrated on the cell membrane and analysed the mechanism of adsorption by fluorescent hyaluronan, chondroitin sulphate and heparin. The influence of the CD44 receptor was evaluated by comparing CD44 expressing human fibroblasts with CD44 deficient HEK cells. Higher amounts of glycosaminoglycans adsorbed to fibroblasts than to HEK cells. When the membrane potential was annihilated by substituting NaCl by KCl in the medium, adsorption was reduced and intracellular pH decrease was abolished. To eliminate other cellular interfering factors, potential-dependent adsorption was demonstrated for hyaluronan which adsorbed to inert gold foils in physiological salt concentrations at pH 7.2 and surface potentials up to 120 mV. From these results, we conclude that large cellular Donnan effects of glycosaminoglycans results from receptor mediated, hydrophobic and ionic adsorption to cell surfaces.
authors.affiliation: Section of Periodontology, Department of Conservative Dentistry, Clinic for Oral, Dental and Maxillofacial Diseases, University Hospital Heidelberg, Heidelberg, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Hagenfeld
authors.forename: Nadine
authors.initials: N
authors.lastname: Kathagen
authors.forename: Peter
authors.initials: P
authors.lastname: Prehm
mesh_terms: D000327:Adsorption / Q000502:physiology*; D002460:Cell Line; D002462:Cell Membrane / Q000502:physiology*; D055590:Electromagnetic Phenomena; D005109:Extracellular Matrix; D005347:Fibroblasts; D006025:Glycosaminoglycans / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D018960:Hyaluronan Receptors; D006820:Hyaluronic Acid / Q000378:metabolism; D008564:Membrane Potentials / Q000502:physiology*; D011189:Potassium Chloride / Q000737:chemistry; D012965:Sodium Chloride / Q000737:chemistry; D013499:Surface Properties
chemical_list: C497483:CD44 protein, human; D006025:Glycosaminoglycans; D018960:Hyaluronan Receptors; D012965:Sodium Chloride; D011189:Potassium Chloride; D006820:Hyaluronic Acid
keywords: DONNAN EFFECT; EXTRACELLULAR MATRIX; HYALURONAN; PROTEOGLYCANS