Knock Greg A, De Silva Anushika S, Snetkov Vladimir A, Siow Richard, Thomas Gavin D, Shiraishi Mitsuya, Walsh Michael P, Ward Jeremy P T, Aaronson Philip I
Dept. of Asthma, Allergy & Respiratory Science, School of Medicine, King's College London, London SE1 9RT, UK.
Am J Physiol Lung Cell Mol Physiol. 2005 Dec;289(6):L1039-48. doi: 10.1152/ajplung.00094.2005. Epub 2005 Jul 29.
The mechanisms through which p38 mitogen-activated protein kinase (p38 MAPK) is involved in smooth muscle contraction remain largely unresolved. We examined the role of p38 MAPK in prostaglandin F(2alpha) (PGF(2alpha))-induced vasoconstriction and in hypoxic pulmonary vasoconstriction (HPV) of rat small intrapulmonary arteries (IPA). The p38 MAPK inhibitors SB-203580 and SB-202190 strongly inhibited PGF(2alpha)-induced vasoconstriction, with IC(50)s of 1.6 and 1.2 microM, whereas the inactive analog SB-202474 was approximately 30-fold less potent. Both transient and sustained phases of HPV were suppressed by SB-203580, but not by SB-202474 (both 2 microM). Western blot analysis revealed that PGF(2alpha) (20 microM) increased phosphorylation of p38 MAPK and of heat shock protein 27 (HSP27), and this was abolished by SB-203580 but not by SB-202474 (both 2 microM). Endothelial denudation or blockade of endothelial nitric oxide (NO) synthase with N(omega)-nitro-L-arginine methyl ester (L-NAME) significantly suppressed the relaxation of PGF(2alpha)-constricted IPA by SB-203580, but not by SB-202474. Similarly, the inhibition of HPV by SB-203580 was prevented by prior treatment with L-NAME. SB-203580 (2 microM), but not SB-202474, enhanced relaxation-induced by the NO donor S-nitroso-N-acetylpenicillamine (SNAP) in endothelium-denuded IPA constricted with PGF(2alpha). In alpha-toxin-permeabilized IPA, SB-203580-induced relaxation occurred in the presence but not the absence of the NO donor sodium nitroprusside (SNP); SB-202474 was without effect even in the presence of SNP. In intact IPA, neither PGF(2alpha)- nor SNAP-mediated changes in cytosolic free Ca(2+) were affected by SB-203580. We conclude that p38 MAPK contributes to PGF(2alpha)- and hypoxia-induced constriction of rat IPA primarily by antagonizing the underlying Ca(2+)-desensitizing actions of NO.
p38丝裂原活化蛋白激酶（p38 MAPK）参与平滑肌收缩的机制在很大程度上仍未得到解决。我们研究了p38 MAPK在前列腺素F(2α)（PGF(2α)）诱导的血管收缩以及大鼠肺内小动脉（IPA）的低氧性肺血管收缩（HPV）中的作用。p38 MAPK抑制剂SB - 203580和SB - 202190强烈抑制PGF(2α)诱导的血管收缩，半数抑制浓度（IC(50)）分别为1.6和1.2微摩尔，而无活性类似物SB - 202474的效力约低30倍。SB - 203580可抑制HPV的瞬时和持续阶段，但SB - 202474（均为2微摩尔）则无此作用。蛋白质印迹分析显示，PGF(2α)（20微摩尔）可增加p38 MAPK和热休克蛋白27（HSP27）的磷酸化，而SB - 203580可消除这种作用，SB - 202474（均为2微摩尔）则不能。用N(ω)-硝基-L-精氨酸甲酯（L-NAME）进行内皮剥脱或阻断内皮型一氧化氮（NO）合酶可显著抑制SB - 203580对PGF(2α)收缩的IPA的舒张作用，但对SB - 202474无此作用。同样，L-NAME预处理可阻止SB - 203580对HPV的抑制作用。SB - 2（2微摩尔）可增强NO供体S-亚硝基-N-乙酰青霉胺（SNAP）对PGF(2α)收缩的内皮剥脱IPA的舒张作用，而SB - 202474则无此作用。在α-毒素通透的IPA中，SB - 203580诱导的舒张在有NO供体硝普钠（SNP）存在时发生，无SNP时则不发生；即使在有SNP存在的情况下，SB - 202474也无作用。在完整的IPA中，SB - 203580对PGF(2α)或SNAP介导的胞质游离Ca(2+)变化均无影响。我们得出结论，p38 MAPK主要通过拮抗NO潜在的Ca(2+)脱敏作用，促进PGF(2α)和低氧诱导的大鼠IPA收缩。
