HUMAN CEREBROMICROVASCULAR ENDOTHELIUM--DISTINCT PEPTIDERGIC RESPONSES IN VITRO

我们先前已经证实内皮素-1(ET-1)诱导受体 (ET/A)介导的脑微血管通透性改变并可能 对促炎剂起作用。最近，我们还展示了 ET-1和ET-3对离子转运系统(Na+-K+-ATPase和 Na~+/K~+/Cl~-共转运) 老鼠的大脑。这里描述的实验检验了 内皮素(ET-1)在另一种离子转运途径上的作用，即 钠/氢(Na+/H+交换系统)在大鼠脑毛细血管中的作用 内皮细胞(RBEC)。 ET-1、ET-2和ET-3刺激红细胞摄取Na+的作用相似 最大刺激(EC50)值(分别为0.7、0.6和1.1 nM)。 该反应可被Na~+/H~+逆向通道阻滞剂N-(乙基-)所抑制。 N-异丙基)-阿米洛利(EIPA)。选择性内皮素A(ET/A) 受体拮抗剂[Cyclo-D-Trp-D-Asp-Pro-D-Val-Leu BQ123]，但不是 内皮素B受体拮抗剂[(Cys11，Cys15)-ET-1(IRL1038)] 或N-顺-2，6-二甲基哌啶甲酰-L-γ-甲基-亮氨酸-D-色氨酸(库姆)-D- NLE-ONA(BQ788)]，抑制ET-1和ET-3刺激的Na+受体 调解。蛋白激酶C(PKC)激活剂[佛波酯 13-乙酸酯(MAO)不能刺激Na+的吸收。钙调素 钙调素(CaM)抑制剂(W7)使ET-1刺激的Na+摄取减少50%，而 蛋白激酶C抑制剂(星形孢子素)无作用，提示ET-1 刺激Na+/H+逆向转运系统与CaM依赖和 PKC非依赖性途径。目前的结果进一步支持了这一想法 内皮素在调节细胞内离子转运中起作用 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..