Glusa E, Adam C
Center for Vascular Biology and Medicine, Friedrich-Schiller-University Jena, Nordhäuser Strasse 78, D-99089 Erfurt, Germany.
Br J Pharmacol. 2001 Jun;133(3):422-8. doi: 10.1038/sj.bjp.0704089.
Serine proteinases elicit profound cellular effects in various tissues mediated by activation of proteinase-activated receptors (PAR). In the present study, we investigated the vascular effects of cathepsin G, a serine proteinase that is present in the azurophil granules of leukocytes and is known to activate several cells that express PARs. In prostaglandin F2alpha (3 microM)-precontracted rings from porcine pulmonary arteries with intact endothelium, cathepsin G caused concentration-dependent relaxant responses (pEC(50)=9.64+/-0.12). The endothelium-dependent relaxant effect of cathepsin G could also be demonstrated in porcine coronary arteries (pEC(50)=9.23+/-0.07). In pulmonary arteries the cathepsin G-induced relaxation was inhibited after blockade of nitric oxide synthesis by L-NAME (200 microM) and was absent in endothelium-denuded vessels. Bradykinin- and cathepsin G-induced relaxant effects were associated with a 5.7 fold and 2.4 fold increase in the concentration of cyclic GMP, respectively. Compared with thrombin and trypsin, which also produced an endothelium-dependent relaxation in pulmonary arteries, cathepsin G was 2.5 and four times more potent, respectively. Cathepsin G caused only small homologous desensitization. In cathepsin G-challenged vessels, thrombin was still able to elicit a relaxant effect. The effects of cathepsin G were blocked by soybean trypsin inhibitor (IC(50)=0.043 microg ml(-1)), suggesting that proteolytic activity is essential for induction of relaxation. Recombinant acetyl-eglin C proved to be a potent inhibitor (IC(50)=0.14 microg ml(-1)) of the cathepsin G effect, whereas neither indomethacin (3 microM) nor the thrombin inhibitor hirudin (5 ATU ml(-1)) elicited any inhibitory activity. Due to their polyanionic structure defibrotide (IC(50)=0.11 microg ml(-1)), heparin (IC(50)=0.48 microg ml(-1)) and suramin (IC(50)=1.85 microg ml(-1)) diminished significantly the relaxation in response to the basic protein cathepsin G. In conclusion, like thrombin and trypsin, cathepsin G is able to induce endothelium-dependent vascular relaxation. It can be released from activated leukocytes at sites of vascular injury and inflammation and, therefore, sufficiently high concentrations might be reached locally in the vascular space to induce vasodilatation.
丝氨酸蛋白酶通过激活蛋白酶激活受体（PAR）在各种组织中引发深刻的细胞效应。在本研究中，我们研究了组织蛋白酶G的血管效应，组织蛋白酶G是一种丝氨酸蛋白酶，存在于白细胞的嗜天青颗粒中，已知可激活几种表达PAR的细胞。在来自具有完整内皮的猪肺动脉的前列腺素F2α（3 microM）预收缩环中，组织蛋白酶G引起浓度依赖性舒张反应（pEC(50)=9.64±0.12）。组织蛋白酶G的内皮依赖性舒张作用在猪冠状动脉中也得到证实（pEC(50)=9.23±0.07）。在肺动脉中，L-NAME（200 microM）阻断一氧化氮合成后，组织蛋白酶G诱导的舒张受到抑制，而在内皮剥脱的血管中则不存在这种舒张。缓激肽和组织蛋白酶G诱导的舒张作用分别与环鸟苷酸浓度增加5.7倍和2.4倍有关。与也在肺动脉中产生内皮依赖性舒张的凝血酶和胰蛋白酶相比，组织蛋白酶G的效力分别高2.5倍和4倍。组织蛋白酶G仅引起轻微的同源脱敏。在受到组织蛋白酶G刺激的血管中，凝血酶仍能引发舒张作用。组织蛋白酶G的作用被大豆胰蛋白酶抑制剂阻断（IC(50)=0.043微克/毫升(-1)），表明蛋白水解活性对于诱导舒张至关重要。重组乙酰艾基林C被证明是组织蛋白酶G作用的有效抑制剂（IC(50)=0.14微克/毫升(-1)），而吲哚美辛（3 microM）和凝血酶抑制剂水蛭素（5 ATU/毫升(-1)）均未引发任何抑制活性。由于其聚阴离子结构，去纤苷（IC(50)=0.11微克/毫升(-1)）、肝素（IC(50)=0.48微克/毫升(-1)）和苏拉明（IC(50)=1.85微克/毫升(-1)）显著降低了对碱性蛋白组织蛋白酶G的舒张反应。总之，与凝血酶和胰蛋白酶一样，组织蛋白酶G能够诱导内皮依赖性血管舒张。它可以从血管损伤和炎症部位的活化白细胞中释放出来，因此，在血管空间中局部可能达到足够高的浓度以诱导血管舒张。
