Mankus R, Schwartz J H, Alexander E A
Thorndike Memorial Laboratory, Boston City Hospital, Massachusetts.
Am J Physiol. 1993 May;264(5 Pt 2):F765-9. doi: 10.1152/ajprenal.1993.264.5.F765.
Chronic acid feeding stimulates the rat inner medullary collecting duct (IMCD) to increase acid secretion in vivo (acidification adaptation), but the mechanism for this phenomenon is unknown. Our purpose was to determine whether IMCD cells undergo adaptation in vitro and to explore the mechanism of this response. Confluent cultured rat IMCD cells were exposed to incubation media supplemented with 10(-7) M deoxycorticosterone acetate, pH 7.0 [acid incubated (AI)] or 7.7 [control (C)], for 48 h, and cell pH (pHi) was determined using 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein. Resting pHi was 7.46 +/- 0.05 for AI and 7.25 +/- 0.04 for C (P < 0.05). N-ethylmaleimide-sensitive pHi recovery after an acute acid pulse was 0.030 +/- 0.002 for AI and 0.020 +/- 0.002 pH U/min for C (P < 0.05). However, when AI and C cells were incubated with 7 x 10(-6) M cycloheximide, the increment in pHi and enhanced proton pump activity was abolished. In addition, exocytic function, as measured by Lucifer yellow release, was increased significantly in AI cells. In summary, incubation of IMCD cells in acid medium stimulates acidification adaptation by a mechanism dependent on new protein synthesis.
长期给予酸刺激可促使大鼠内髓集合管（IMCD）在体内增加酸分泌（酸化适应），但此现象的机制尚不清楚。我们的目的是确定IMCD细胞在体外是否会发生适应，并探究这种反应的机制。将汇合培养的大鼠IMCD细胞暴露于补充有10^(-7) M醋酸脱氧皮质酮、pH 7.0 [酸孵育（AI）] 或7.7 [对照（C）] 的孵育培养基中48小时，使用2',7'-双（羧乙基）-5（6）-羧基荧光素测定细胞pH（pHi）。AI组的静息pHi为7.46±0.05，C组为7.25±0.04（P<0.05）。急性酸脉冲后，N-乙基马来酰亚胺敏感的pHi恢复在AI组为0.030±0.002，C组为0.020±0.002 pH单位/分钟（P<0.05）。然而，当AI组和C组细胞与7×10^(-6) M环己酰亚胺一起孵育时，pHi的升高和质子泵活性的增强被消除。此外，通过荧光黄释放测量的胞吐功能在AI组细胞中显著增加。总之，将IMCD细胞置于酸性培养基中孵育可通过一种依赖于新蛋白质合成的机制刺激酸化适应。
