Kaissling B, Stanton B A
Anatomisches Institut der Universitat, Basel, Switzerland.
Am J Physiol. 1988 Dec;255(6 Pt 2):F1256-68. doi: 10.1152/ajprenal.1988.255.6.F1256.
We examined the effects of a chronic increase in tubular sodium delivery on the structure of the distal convoluted tubule (DCT), connecting tubule (CNT), and cortical collecting duct of male Sprague-Dawley rats. Furosemide (12 mg/day) was administered by osmotic minipump for 6 days to increase the rate of sodium delivery to these segments and thereby stimulate sodium uptake. To prevent volume depletion, the furosemide-treated animals were given a drinking solution containing 0.8% NaCl and 0.1% KCl. Control animals were given vehicle (0.9% NaCl) by osmotic minipump and they drank tap water. Furosemide dramatically increased urinary fluid and sodium excretion and decreased urine osmolality threefold vs. control. Furosemide treatment was associated with an increase in epithelial volume of DCT cells, CNT cells, and principal cells and an increase in the basolateral membrane area and mitochondrial volume of each cell type. These alterations in cell structure were not related to changes in plasma aldosterone, glucocorticoid, or arginine vasopressin levels. We conclude that an increase in cell sodium uptake regulates the ultrastructure of the distal tubule.
我们研究了肾小管钠输送长期增加对雄性Sprague-Dawley大鼠远曲小管（DCT）、连接小管（CNT）和皮质集合管结构的影响。通过渗透微型泵给予呋塞米（12毫克/天），持续6天，以增加这些节段的钠输送速率，从而刺激钠摄取。为防止容量耗竭，给接受呋塞米治疗的动物饮用含有0.8%氯化钠和0.1%氯化钾的溶液。对照动物通过渗透微型泵给予载体（0.9%氯化钠），并饮用自来水。与对照相比，呋塞米显著增加了尿液量和钠排泄，并使尿渗透压降低了三倍。呋塞米治疗与DCT细胞、CNT细胞和主细胞的上皮体积增加以及每种细胞类型的基底外侧膜面积和线粒体体积增加有关。细胞结构的这些改变与血浆醛固酮、糖皮质激素或精氨酸加压素水平的变化无关。我们得出结论，细胞钠摄取的增加调节远曲小管的超微结构。
