Minassian A, O'Hare D, Parker K H, Urban J P, Warensjo K, Winlove C P
Department of Biological and Medical Systems, Imperial College of Science, London, England.
J Orthop Res. 1998 Nov;16(6):720-5. doi: 10.1002/jor.1100160614.
The charge structure of the surface of articular cartilage determines its interactions with the macromolecules and cells of synovial fluid. It may thereby be important to the physiological function and pathological degeneration of the tissue. To determine whether the electrokinetic properties of the surface differ from those of the bulk tissue, we measured the streaming potential generated by the flow of electrolyte over the surface of a cartilage plug mounted in a chamber built for that purpose. We then calculated the effective surface charge density. In nonfibrillated cartilage from the human femoral head, the surface charge density, 0.037+/-0.004 Cm(-2) (mean+/-SD), was approximately half that measured at the surface of slices cut from the middle and deep zones. In addition, the surface charge density fell relatively little at low pH; this is consistent with a higher proportion of strongly acidic groups. The variations in surface charge density were found to be similar to those in total fixed charge density in the slices by the tracer cation method. Therefore, no evidence exists that the actual surface differs in composition from the immediately underlying matrix. The addition of synovial fluid (0.0025 ml/ml) to the superfusing solution reduced the surface charge density by 25+/-9% (n=5), and we attributed this to the binding of synovial-fluid macromolecules.
关节软骨表面的电荷结构决定了其与滑液中的大分子和细胞之间的相互作用。因此，这可能对该组织的生理功能和病理退变具有重要意义。为了确定表面的电动特性是否与整体组织不同，我们测量了电解质在安装于为此目的构建的腔室中的软骨塞表面流动时产生的流动电位。然后我们计算了有效表面电荷密度。在取自人类股骨头的非原纤维形成软骨中，表面电荷密度为0.037±0.004 Cm(-2)（平均值±标准差），约为从中间和深部区域切取的切片表面所测值的一半。此外，在低pH值时表面电荷密度下降相对较小；这与较高比例的强酸性基团一致。通过示踪阳离子法发现表面电荷密度的变化与切片中总固定电荷密度的变化相似。因此，没有证据表明实际表面在组成上与紧邻的下层基质不同。向灌注溶液中添加滑液（0.0025 ml/ml）使表面电荷密度降低了25±9%（n = 5），我们将此归因于滑液大分子的结合。
