Ishikawa S, Okada K, Saito T
Department of Medicine, Jichi Medical School, Tochigi, Japan.
Kidney Int. 1993 Dec;44(6):1235-41. doi: 10.1038/ki.1993.374.
We examined what mechanisms are involved in the alteration by chloride (Cl-) removal of arginine vasopressin (AVP)-induced cellular cAMP production, and cellular free calcium ([Ca2+]i) mobilization in rat renal papillary collecting tubule cells in culture, using two buffer systems: bicarbonate and non-bicarbonate buffers. The first study was performed in the bicarbonate-supplemented buffer. Removal of Cl-, which was replaced by methylsulfonate or gluconate, increased cellular pH (pHi) from 7.19 to 7.26. AVP increased cellular cAMP production in a dose-dependent manner; 1 x 10(-9) and 1 x 10(-7) M AVP-induced increases in cellular cAMP production were significantly enhanced by the Cl- removal. Also, 1 x 10(-7) M AVP-mobilized [Ca2+]i was augmented by the Cl- removal (181.3 vs. 224.5 nM, P < 0.05). The second study was carried out with the Krebs-Ringer buffered saline (KRB). Removal of Cl- lowered pHi from 7.20 to 7.09. AVP-induced increases in cellular cAMP production were significantly reduced in the Cl(-)-free KRB compared to those in the KRB. The reduction was obtained with KRB containing less than 25 mM Cl-. Similar results were obtained with 2 x 10(-8) M forskolin, a diterpene activator of adenylate cyclase. 1 x 10(-7) M AVP-mobilized [Ca2+]i was also diminished by the Cl(-)-free KRB. These results indicate that Cl- depletion affects the cellular response to AVP mediated via the changes in pHi in renal papillary collecting tubule cells.(ABSTRACT TRUNCATED AT 250 WORDS)
碳酸氢盐缓冲液和非碳酸氢盐缓冲液，研究了在培养的大鼠肾乳头集合管细胞中，去除氯离子（Cl-）改变精氨酸加压素（AVP）诱导的细胞环磷酸腺苷（cAMP）生成及细胞游离钙（[Ca2+]i）动员涉及何种机制。第一项研究在补充了碳酸氢盐的缓冲液中进行。用甲磺酸盐或葡萄糖酸盐替代Cl-后，细胞内pH（pHi）从7.19升至7.26。AVP以剂量依赖方式增加细胞cAMP生成；去除Cl-可显著增强1×10-9和1×10-7 M AVP诱导的细胞cAMP生成增加。此外，去除Cl-可增强1×10-7 M AVP动员的[Ca2+]i（181.3对224.5 nM，P<0.05）。第二项研究使用 Krebs-Ringer 缓冲盐水（KRB）进行。去除Cl-使pHi从7.20降至7.09。与KRB相比，无Cl-的KRB中AVP诱导的细胞cAMP生成增加显著减少。当KRB中Cl-含量低于25 mM时会出现这种减少。用2×10-8 M毛喉素（一种腺苷酸环化酶的二萜激活剂）也得到了类似结果。无Cl-的KRB也使1×10-7 M AVP动员的[Ca2+]i减少。这些结果表明，Cl-耗竭通过肾乳头集合管细胞pHi的变化影响细胞对AVP的反应。（摘要截断于250字）
