Silver I A, Murrills R J, Etherington D J
Department of Pathology, Medical School, University Walk, Bristol, United Kingdom.
Exp Cell Res. 1988 Apr;175(2):266-76. doi: 10.1016/0014-4827(88)90191-7.
Osteoclasts and activated macrophages in culture were shown to generate an acidic microenvironment specifically in the attachment zone between the cell and the base of the culture dish. Measurements using pH microelectrodes revealed that osteoclasts, when firmly attached, could achieve a pH fall of about 1 unit min-1 to a limit value of pH 3.0 or less. Activated macrophages produced a slower fall of 0.5-2 pH units h-1 and a limit value of pH 3.6-3.7 was generally detected. The method of activation was relatively unimportant, but where macrophages formed clumps the pH effect was reinforced. Osteoclasts were also examined in situ in osteoporotic bone fragments in rabbit ear chambers, using a combination H+ and Ca2+ double-barrelled electrode. The pH readings reached a lower limit of 4.7 and the calcium concentration rose to a maximum of 40 mM in the erosion sites. In vivo such acid conditions would favor the direct extracellular action of secreted lysosomal proteinases in the degradation of collagen by both cell types.
研究表明，培养中的破骨细胞和活化巨噬细胞会在细胞与培养皿底部之间的附着区域特异性地产生酸性微环境。使用pH微电极进行的测量显示，破骨细胞在牢固附着时，每分钟可使pH值下降约1个单位，直至pH值降至3.0或更低的极限值。活化巨噬细胞使pH值下降的速度较慢，每小时下降0.5 - 2个pH单位，通常检测到的极限值为pH 3.6 - 3.7。活化方法相对不太重要，但当巨噬细胞形成团块时，pH效应会增强。还使用H⁺和Ca²⁺双管电极对兔耳室骨质疏松骨碎片中的破骨细胞进行了原位检测。在侵蚀部位，pH读数下限达到4.7，钙浓度最高升至40 mM。在体内，这种酸性条件有利于两种细胞类型分泌的溶酶体蛋白酶在胶原蛋白降解过程中直接发挥细胞外作用。
