HUMAN CEREBROMICROVASCULAR ENDOTHELIUM--DISTINCT PEPTIDERGIC RESPONSES IN VITRO

我们以前已经证实内皮素-1（ET-1）诱导受体 (ET/A）介导的微血管通透性变化， 对促炎剂起作用。 最近，我们还证明了 ET-1和ET-3调节离子转运系统（Na+-K+-ATP酶， Na ~+/K ~+/Cl ~-共转运）在血管内皮细胞中的作用 老鼠的大脑这里描述的实验检查了 内皮素（ET-1）的另一种离子转运途径，即 大鼠脑毛细血管钠/氢交换系统 内皮细胞（RBEC）。 ET-1、ET-2和ET-3刺激REBC的Na+摄取， 最大刺激（EC 50）值（分别为0.7、0.6和1.1 nM）。 此反应可被Na+ /H+逆向转运抑制剂N-（乙基- N-异丙基）-阿米洛利（EIPA）。 选择性内皮素A（ET/A） 受体拮抗剂[环-D-Trp-D-Asp-Pro-D-Val-Leu BQ 123]，但不 内皮素B（ET/B）受体拮抗剂[（Cys 11，Cys 15）-ET-1（IRL 1038）] 或N-顺式-2，6-二甲基哌啶羰基-L-γ MeLeu-D-trp（COOMe）-D- Nle-ONa（BQ 788）]对ET-1和ET-3刺激的Na+受体均有抑制作用 调解 蛋白激酶C（PKC）激活剂[佛波醇12-肉豆蔻酸酯 13-乙酸（MAO）不能刺激Na+摄取。 钙-钙调素 (CaM)抑制剂（W7）使ET-1刺激的Na+摄取减少50%，而 PKC抑制剂（staurosporine）无影响，表明ET-1 Na+ /H+反向转运系统的刺激与钙调素依赖性 PKC非依赖性通路。目前的结果进一步支持了这一观点 内皮素在调节跨血管的离子转运中起作用， 血脑屏障

We have previously established that endothelin-1 (ET-1) induces receptor (ET/A) mediated cerebromicrovascular permeability changes and may function on a proinflammatory agent. Lately, we have also demonstrated that ET-1 and ET-3 modulates the ion transport systems (Na+-K+-ATPase and Na+/K+/Cl--cotransport) in endothelial cells derived from capillaries of rat brain. The experiments described here examined the effect of endothelin (ET-1) on another ion transport pathway, namely sodium/hydrogen (Na+/H+ exchange system) in rat brain capillary endothelium (RBEC). ET-1, ET-2 and ET-3 stimulated Na+ uptake into REBC with similar half- maximal stimulation (EC50 ) values (0.7, 0.6, and 1.1 nM, respectively). This reaction was inhibited by the Na+ /H+ antiport inhibitor, N-(ethyl- N-isopropyl)-amiloride (EIPA). The selective endothelin A (ET/A ) receptor-antagonist [Cyclo-D-Trp-D-Asp-Pro-D-Val-Leu BQ123], but not endothelin B (ET/B) receptor-antagonists[(Cys11, Cys15)-ET-1 (IRL1038) or N-cis-2,6-dimethylprperidinocarbonyl-L-gamma MeLeu-D-trp (COOMe)-D- Nle-ONa (BQ788)], inhibited both ET-1 and ET-3 stimulated Na+ receptor mediation. The protein kinase C (PKC) activator [phorbol 12-myristate 13-acetate (MAO) failed to stimulate Na+uptake. The calcium-calmodulin (CaM) inhibitor (W7) reduced ET-1 stimulate Na+uptake by 50%, whereas the PKC inhibitor (staurosporine) had no effect, indicating that ET-1 stimulation of Na+ /H+ antiport system is linked to a CaM-dependent and PKC-independent pathway. The present results further support the idea that endothelins play a role in regulating ion transport across the blood-brain barrier..