Madsen K M, Tisher C C
Lab Invest. 1984 Sep;51(3):268-76.
The outer medullary collecting duct which is composed of both principal and intercalated cells is involved in hydrogen ion secretion. In the turtle urinary bladder stimulation of hydrogen ion secretion is associated with ultrastructural changes in the mitochondria-rich cells, suggesting that membrane and possibly a proton pump are being transferred from apical tubulovesicular structures and inserted into the apical plasma membrane. Since the intercalated cells resemble the mitochondria-rich cells, this study was initiated to determine whether or not similar changes occur in the outer medullary collecting duct during chronic metabolic acidosis. Rats received ammonium chloride in their drinking water for 15 days and as a daily gavage for 3 days before sacrifice. Control rats received regular tap water. After collection of physiologic data the kidneys were fixed by in vivo perfusion with glutaraldehyde and processed for electron microscopy. No changes were observed in the principal cells. Morphometric analyses of the intercalated cells in both the outer and inner stripe revealed a significant increase in the surface density of the apical plasma membrane concomitant with a striking depletion of the tubulovesicular structures in the apical plasma region of the cell with chronic metabolic acidosis. These findings suggest that in response to chronic metabolic acidosis membrane, possibly containing a proton pump, is transported from the tubulovesicular membrane compartment to the apical plasma membrane of the intercalated cell.
由主细胞和闰细胞组成的外髓集合管参与氢离子分泌。在龟的膀胱中，氢离子分泌的刺激与富含线粒体的细胞的超微结构变化有关，这表明膜以及可能的质子泵正从顶端小管泡状结构转移并插入顶端质膜。由于闰细胞类似于富含线粒体的细胞，因此开展了本研究以确定在慢性代谢性酸中毒期间外髓集合管是否会发生类似变化。大鼠在饮用水中摄入氯化铵15天，并在处死前3天每天进行灌胃。对照大鼠饮用普通自来水。收集生理数据后，通过戊二醛体内灌注固定肾脏并进行电子显微镜处理。在主细胞中未观察到变化。对内外带闰细胞的形态计量分析显示，慢性代谢性酸中毒时，顶端质膜的表面密度显著增加，同时细胞顶端质膜区域的小管泡状结构明显减少。这些发现表明，响应慢性代谢性酸中毒时，可能含有质子泵的膜从管泡膜区室转运至闰细胞的顶端质膜。
