Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan.
Peptides. 2010 May;31(5):909-14. doi: 10.1016/j.peptides.2010.02.013. Epub 2010 Feb 25.
The anti-hypertensive peptide Arg-Ile-Tyr, which was isolated based on its inhibitory activity (IC(50)=28microM) for angiotensin I-converting enzyme (ACE) from the subtilisin digest of rapeseed protein, exhibited vasorelaxing activity (EC(50)=5.1microM) in an endothelium-dependent manner in the mesenteric artery of spontaneously hypertensive rats (SHRs). We named the peptide rapakinin. ACE inhibitors are reported to induce nitric oxide (NO)-dependent vasorelaxation by elevating the endogenous bradykinin level; however, the vasorelaxation induced by 10microM of rapakinin was blocked only insignificantly by HOE140 or N(G)-nitro-l-arginine methyl ester (l-NAME), antagonists of bradykinin B(2) receptor and an inhibitor of NO synthase, respectively. On the other hand, the vasorelaxation induced by 10microM rapakinin was significantly blocked by indomethacin and CAY10441, a cyclooxygenase (COX) inhibitor and an antagonist of the IP receptor, respectively. The vasorelaxing activity of rapakinin was also blocked by lorglumide, an antagonist of the cholecystokinin (CCK) CCK(1) receptor, although rapakinin has no affinity for the IP and CCK(1) receptors. The vasorelaxation induced by 10microM iloprost, an IP receptor agonist, was also blocked by lorglumide, suggesting that CCK-CCK(1) receptor system is activated downstream of the PGI(2)-IP receptor system. The anti-hypertensive activity of rapakinin after oral administration in SHRs was also blocked by CAY10441 and lorglumide. These results suggest that the anti-hypertensive activity of rapakinin might be mediated mainly by the PGI(2)-IP receptor, followed by CCK-CCK(1) receptor-dependent vasorelaxation.
从菜籽蛋白的枯草杆菌蛋白酶消化物中分离得到的具有血管紧张素 I 转换酶（ACE）抑制活性（IC50=28μM）的抗高血压肽 Arg-Ile-Tyr，在自发性高血压大鼠（SHR）的肠系膜动脉中以内皮依赖性方式表现出血管舒张活性（EC50=5.1μM）。我们将该肽命名为 rapakinin。据报道，ACE 抑制剂通过升高内源性缓激肽水平诱导一氧化氮（NO）依赖性血管舒张；然而，10μM rapakinin 诱导的血管舒张仅被 HOE140 或 N(G)-硝基-L-精氨酸甲酯（l-NAME）轻微阻断，HOE140 和 l-NAME 分别是缓激肽 B2 受体的拮抗剂和 NO 合酶抑制剂。另一方面，10μM rapakinin 诱导的血管舒张被吲哚美辛和 CAY10441 显著阻断，CAY10441 是环氧化酶（COX）抑制剂和 IP 受体拮抗剂。尽管 rapakinin 对 IP 和 CCK1 受体没有亲和力，但 rapakinin 的血管舒张活性也被 CCK1 受体拮抗剂 lorglumide 阻断。IP 受体激动剂 iloprost 诱导的 10μM 血管舒张也被 lorglumide 阻断，表明 CCK-CCK1 受体系统在 PGI2-IP 受体系统下游被激活。在 SHR 中口服给予 rapakinin 后的抗高血压活性也被 CAY10441 和 lorglumide 阻断。这些结果表明，rapakinin 的抗高血压活性可能主要通过 PGI2-IP 受体介导，随后是 CCK-CCK1 受体依赖性血管舒张。
