The effect of osmotic and mechanical pressures on water partitioning in articular cartilage

• Published in: Biochimica et biophysica acta Vol. 1073; no. 2; pp. 285 - 294
• Main Authors: Maroudas, A., Wachtel, E., Grushko, G., Katz, E.P., Weinberg, P.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 04.03.1991; Elsevier
• Subjects: Adult; Aged; Animals; Biological and medical sciences; Body Water - metabolism; Cartilage structure; Cartilage, Articular - chemistry; Cartilage, Articular - metabolism; Cattle; Cell physiology; Collagen; Collagen - analysis; Dialysis; Effects of physical and chemical agents; Extrafibrillar water; Fundamental and applied biological sciences. Psychology; Humans; Intrafibrillar water; Middle Aged; Molecular and cellular biology; Osmotic Pressure; Photeoglycan; Polyethylene Glycols; Pressure; Serum Albumin - metabolism; X-Ray Diffraction; Extrafibrillar water; Collagen; FCD; PG; GAG; Photeoglycan; Intrafibrillar water; Cartilage structure; Water; Human; Proteoglycan; Articular cartilage; Correlation analysis; Content; Partition coefficient; Glycoproteins; Osmotic pressure; X ray diffraction; Quantitative analysis
• ISSN: 0304-4165; 0006-3002; 1872-8006
• DOI: 10.1016/0304-4165(91)90133-2

X-ray diffraction measurements on native and proteoglycan-free articular cartilage have been made in order to test the dependence of the lateral packing of the collagen molecules on the osmotic pressure gradient, either naturally occurring or externally applied, between the intra- and extrafibrillar compartments. From the information on collagen packing we have been able to calculate, albeit with several assumptions, the amount of intrafibrillar water as a function of pressure. In parallel with the above measurements, we have quantitated, using serum albumin partitioning, the intrafibrillar water in proteoglycan-free cartilage, as a function of mechanically applied pressure. The results of both sets of experiments lead to the conclusion that the molecular packing density, and hence the intrafibrillar water content, are a function of the osmotic pressure difference between the extrafibrillar and intrafibrillar spaces or the equivalent mechanically applied pressure. The determination of intrafibrillar water has enabled us to calculate, from measured values of fixed charge density, the internal osmotic pressure of cartilage specimens, both in compressed and uncompressed states.