Control of cAMP in lung endothelial cell phenotypes. Implications for control of barrier function
Control of cAMP in lung endothelial cell phenotypes. Implications for control of barrier function
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DOI：
10.1152/ajplung.1999.277.1.l119
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发表时间：
1999-07-01
影响因子：
4.9
通讯作者：
Thompson, WJ
中科院分区：
文献类型：
--
作者：
Stevens, T;Creighton, J;Thompson, WJ
肺微血管内皮细胞（PMVEC）比肺动脉内皮细胞（PAEC）形成更严格的大分子通量屏障;然而，负责PMVEC这种内在特征的机制尚不清楚。由于cAMP改善内皮屏障功能，我们假设cAMP合成和/或降解的酶调节差异独特地建立了PMVEC中的含量升高。PMVEC的基础cAMP浓度比PAEC高20%;然而，增加的含量伴随着93%的ATP-cAMP转化率降低。与PAEC相比，PMVEC对β-肾上腺素能激动剂（异丙肾上腺素）或直接腺苷酸环化酶（毛喉素）激活的反应性减弱，对磷酸二酯酶抑制剂（咯利普兰）的反应性增加。虽然这两种类型的内皮细胞表达钙抑制腺苷酸环化酶，组成PR NEC cAMP积累没有抑制细胞质钙的生理上升，而PAEC cAMP积累抑制30%的钙。通过最大激活钙库操作的钙进入或用咯利普兰将ATP转化为cAMP来增加PMVEC钙进入，揭示了腺苷酸环化酶的钙抑制作用。这些数据表明，抑制钙进入和低ATP-cAMP转换固有地影响钙敏感性。腺苷酸环化酶与cAMP磷酸二酯酶的比例调节cAMP水平升高相比，PAEC，这可能有助于增强微血管屏障功能。
Pulmonary microvascular endothelial cells (PMVECs) form a more restrictive barrier to macromolecular flux than pulmonary arterial endothelial cells (PAECs); however, the mechanisms responsible for this intrinsic feature of PMVECs are unknown. Because cAMP improves endothelial barrier function, we hypothesized that differences in enzyme regulation of cAMP synthesis and/or degradation uniquely establish an elevated content in PMVECs. PMVECs possessed 20% higher basal cAMP concentrations than did PAECs; however, increased content was accompanied by 93% lower ATP-to-cAMP conversion rates. In PMVECs, responsiveness to beta-adrenergic agonist (isoproterenol) or direct adenylyl cyclase (forskolin) activation was attenuated and responsiveness to phosphodiesterase inhibition (rolipram) was increased compared with those in PAECs. Although both types of endothelial cells express calcium-inhibited adenylyl cyclase, constitutive PR NEC cAMP accumulation was not inhibited by physiological rises in cytosolic calcium, whereas PAEC cAMP accumulation was inhibited 30% by calcium. Increasing either PMVEC calcium entry by maximal activation of store-operated calcium entry or ATP-to-cAMP conversion with rolipram unmasked calcium inhibition of adenylyl cyclase. These data indicate that suppressed calcium entry and low ATP-to-cAMP conversion intrinsically influence calcium sensitivity. Adenylyl cyclase-to-cAMP phosphodiesterase ratios regulate cAMP at elevated levels compared with PAECs, which likely contribute to enhanced microvascular barrier function.