Yanagawa N, Jo O D
Am J Physiol. 1986 May;250(5 Pt 2):F942-8. doi: 10.1152/ajprenal.1986.250.5.F942.
Using a glucose microassay and in vitro isolated renal tubule perfusion technique, we have studied the actions of parathyroid hormone (PTH) on gluconeogenesis (GNG) and fluid (Jv) and phosphate (Jp) transport rates in isolated rabbit renal proximal tubules. In proximal straight tubules (PST), PTH stimulated GNG and inhibited Jv and Jp. In proximal convoluted tubules (PCT), PTH inhibited Jv but failed to affect GNG and Jp. An increase in Ca concentration, however, stimulated GNG and allowed PTH to inhibit Jp in PCT. Addition of the intracellular Ca antagonists trifluoperazine and N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7) abolished the inhibitory effects of PTH on Jv and Jp in both PCT and PST. In conclusion, these studies suggest that Ca-dependent intracellular pathways may be involved in the actions of PTH in rabbit renal proximal tubules. The altered response to PTH in rabbit PCT may be due to alterations in the response of intracellular Ca to the hormone.
利用葡萄糖微量测定法和体外分离肾小管灌注技术，我们研究了甲状旁腺激素（PTH）对分离的兔肾近端小管糖异生（GNG）、液体（Jv）和磷酸盐（Jp）转运速率的作用。在近端直小管（PST）中，PTH刺激GNG并抑制Jv和Jp。在近端曲小管（PCT）中，PTH抑制Jv，但不影响GNG和Jp。然而，钙浓度的增加刺激了GNG，并使PTH能够抑制PCT中的Jp。添加细胞内钙拮抗剂三氟拉嗪和N-（6-氨基己基）-5-氯-1-萘磺酰胺（W-7）消除了PTH对PCT和PST中Jv和Jp的抑制作用。总之，这些研究表明，钙依赖性细胞内途径可能参与了PTH在兔肾近端小管中的作用。兔PCT对PTH反应的改变可能是由于细胞内钙对该激素反应的改变。
