Natarajan R, Stern N, Hsueh W, Do Y, Nadler J
Los Angeles County, University of Southern California Medical Center, School of Medicine 90033.
J Clin Endocrinol Metab. 1988 Sep;67(3):584-91. doi: 10.1210/jcem-67-3-584.
We studied the role of the lipoxygenase pathway of arachidonic acid metabolism in angiotensin II (AII)-stimulated aldosterone secretion in normal and adenomatous human adrenal glomerulosa tissue. In freshly isolated normal adrenal glomerulosa cells, the AII-mediated stimulation of aldosterone secretion was not altered by cyclooxygenase blockade with ibuprofen. In contrast, BW755c (10(-5) mol/L), a nonselective lipoxygenase inhibitor, and baicalein (10(-6) mol/L), a more selective 12-lipoxygenase blocker, inhibited AII-mediated aldosterone secretion, but did not alter basal aldosterone secretion. The glomerulosa cells produced the lipoxygenase products 12- and 15-hydroxyeicosatetraenoic acid (HETE) in the basal state, as measured by high pressure liquid chromatography and RIA. However, AII selectively stimulated only 12-HETE production [basal, 1329 +/- 207 (+/- SE) pg (3.99 +/- 0.62 pmol)/10(5) cells.h; AII, 2365 +/- 333 (7.09 +/- 1.0); n = 9; P less than 0.02], suggesting that 12-lipoxygenase activation may be involved in AII-mediated aldosterone secretion by normal cells. In addition, the lipoxygenase inhibitors that blocked AII-mediated aldosterone secretion also prevented AII-mediated 12-HETE formation. In contrast, neither ACTH nor K+ stimulated 12-HETE formation, suggesting that 12-lipoxygenase activation is primarily involved in AII action in normal glomerulosa cells. BW755c caused a marked dose-dependent inhibition of basal aldosterone secretion in freshly isolated cells from aldosterone-producing adenomas [APA; basal, 66 +/- 3 ng (182 +/- 8 pmol)/10(6) cells.h; 10(-5) mol/L BW755c, 49 +/- 2 (136 +/- 6); 10(-4) mol/L BW755c, 30 +/- 2 (83 +/- 6)]. In contrast, the cyclooxygenase inhibitor indomethacin and the selective 5-lipoxygenase inhibitor U60257 did not alter basal aldosterone secretion by these cells. The APA cells produced 12- and 15-HETE, and BW755c at the same dose that inhibited aldosterone secretion also inhibited the production of both 12- and 15-HETE. In the cultured APA cells, AII-stimulated aldosterone secretion was inhibited by BW755c [basal, 26 +/- 8 pg/mL (72.0 +/- 22.1 pmol/L); AII, 336 +/- 79 (930 +/- 218); AII plus BW755c, 92 +/- 38 (255 +/- 105) n = 13; P less than 0.01]. The lipoxygenase products 12- and 15-HETE restored the stimulatory effect of AII during inhibition by BW755c, indicating a role for these lipoxygenase pathways in AII-mediated aldosterone secretion in APA cells. These results suggest that the stimulatory effects of AII on aldosterone secretion are mediated by stimulation of the lipoxygenase pathway in human zona glomerulosa cells.
我们研究了花生四烯酸代谢的脂氧合酶途径在正常和腺瘤性人肾上腺球状带组织中血管紧张素II（AII）刺激醛固酮分泌过程中的作用。在新鲜分离的正常肾上腺球状带细胞中，用布洛芬进行环氧化酶阻断并未改变AII介导的醛固酮分泌刺激作用。相比之下，非选择性脂氧合酶抑制剂BW755c（10⁻⁵mol/L）和更具选择性的12 - 脂氧合酶阻滞剂黄芩素（10⁻⁶mol/L）抑制了AII介导的醛固酮分泌，但未改变基础醛固酮分泌。通过高压液相色谱和放射免疫分析法测定，球状带细胞在基础状态下产生脂氧合酶产物12 - 和15 - 羟基二十碳四烯酸（HETE）。然而，AII仅选择性刺激12 - HETE的产生[基础状态，1329±207（±SE）pg（3.99±0.62 pmol）/10⁵细胞·小时；AII刺激后，2365±333（7.09±1.0）；n = 9；P＜0.02]，这表明12 - 脂氧合酶的激活可能参与正常细胞中AII介导的醛固酮分泌。此外，阻断AII介导的醛固酮分泌的脂氧合酶抑制剂也阻止了AII介导的12 - HETE形成。相比之下，促肾上腺皮质激素（ACTH）和钾离子（K⁺）均未刺激12 - HETE的形成，这表明12 - 脂氧合酶的激活主要参与正常球状带细胞中的AII作用。BW755c对来自醛固酮产生性腺瘤[APA]的新鲜分离细胞的基础醛固酮分泌产生明显的剂量依赖性抑制作用[基础状态，66±3 ng（182±8 pmol）/10⁶细胞·小时；10⁻⁵mol/L BW755c作用后，49±2（136±6）；10⁻⁴mol/L BW755c作用后，30±2（83±6）]。相比之下，环氧化酶抑制剂吲哚美辛和选择性5 - 脂氧合酶抑制剂U60257并未改变这些细胞的基础醛固酮分泌。APA细胞产生12 - 和15 - HETE，且抑制醛固酮分泌的相同剂量的BW755c也抑制了12 - 和15 - HETE的产生。在培养的APA细胞中，BW755c抑制了AII刺激的醛固酮分泌[基础状态，26±8 pg/mL（72.0±22.1 pmol/L）；AII刺激后，336±79（930±218）；AII加BW755c作用后，92±38（255±105）n = 13；P＜0.01]。脂氧合酶产物12 - 和15 - HETE在BW755c抑制过程中恢复了AII的刺激作用，表明这些脂氧合酶途径在APA细胞中AII介导的醛固酮分泌中起作用。这些结果表明，AII对醛固酮分泌的刺激作用是通过刺激人球状带细胞中的脂氧合酶途径介导的。
