Effect of luminal angiotensin II on proximal tubule fluid transport: role of apical phospholipase A2.
Effect of luminal angiotensin II on proximal tubule fluid transport: role of apical phospholipase A2.
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管腔血管紧张素 II 对近曲小管液体转运的影响：顶端磷脂酶 A2 的作用。
DOI：
10.1152/ajprenal.1994.266.2.f202
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
Yanagawa,N
中科院分区：
文献类型：
--
作者：
Li,L;Wang,YP;Capparelli,AW;Jo,OD;Yanagawa,N
最近的显微穿刺术研究表明，近端肾小管液中存在高浓度的血管紧张素II(Ang II)。在本研究中，我们观察了管腔Ang II单独以及与管周Ang II联合应用对离体灌流兔近曲小管液体转运(JV)的影响。与管周血管紧张素Ⅱ相比，管腔血管紧张素Ⅱ对JV有相似但更强的双相效应。在10(-11)M时，管腔Ang II最大限度地增加JV至基线的204+/-22%，而管周Ang II在10(-10)M时最大增加142+/-10%；在10(-8)M时，管腔Ang II将JV抑制至基线的9.7+/-16%，而管周Ang II则抑制JV+/-14%。当管腔Ang II与管周Ang II合用时，管腔Ang II和管周Ang II的作用不是相加的。然而，当浓度组合在一起时，否则会对合资企业产生相反的影响，刺激效应占主导地位。为支持心尖磷脂酶A2(PLA2)在腔Ang II作用中的作用，Ang II刺激离体刷状缘膜囊泡的PLA2活性，在腔灌流液中加入PLA2抑制剂甲平或地布卡因可减弱腔Ang II对JV的影响。综上所述，这些研究表明，管腔Ang II对近曲小管JV的有效作用涉及刷状缘膜PLA2的激活。当管腔Ang II和管周Ang II联合使用时，它们在近端小管JV上协同发挥作用。
Recent micropuncture studies showed the existence of high concentrations of angiotensin II (ANG II) in proximal tubular fluid. In the present study, we have examined the effect of luminal ANG II, alone and in combination with peritubular ANG II, on fluid transport (JV) in the isolated perfused rabbit proximal convoluted tubule. In comparison with peritubular ANG II, luminal ANG II caused a similar but more potent biphasic effect on JV. At 10(-11) M, luminal ANG II maximally increased JV to 204 +/- 22% of the baseline compared with 142 +/- 10% by peritubular ANG II at 10(-10) M. At 10(-8) M, luminal ANG II suppressed JV to 9.7 +/- 16% of the baseline compared with 64 +/- 14% by peritubular ANG II. When luminal and peritubular ANG II were combined at concentrations that impose similar effect on JV, the effects of luminal and peritubular ANG II were not additive. However, when combined at concentrations that would otherwise impose opposing effects on JV, the stimulatory effect predominated. In support of the role of apical phospholipase A2 (PLA2) on the effect of luminal ANG II, ANG II stimulated PLA2 activity in isolated brush-border membrane vesicles, and addition of PLA2 inhibitor, mepacrine or dibucaine, to the luminal perfusate attenuated the effect of luminal ANG II on JV. In summary, these studies show a potent effect of luminal ANG II on proximal tubule JV involving activation of brush-border membrane PLA2. When combined, luminal and peritubular ANG II exert their effects in concert on proximal tubule JV.