Bhattacharya A, Smith G F, Cohen M L
Eli Lilly and Company, Neuroscience Drug Discovery, Indianapolis, Indiana 46282, USA.
J Pharmacol Exp Ther. 2001 May;297(2):573-81.
The active site tripeptide arginal inhibitor of thrombin, LY287045, was used to study thrombin-induced aortic relaxation and contraction, two responses that differ both pharmacologically and physiologically. Although thrombin (10(-7) M) and trypsin (10(-6) M) were tachyphylactic upon repeated administration, trypsin contracted the aorta following thrombin-induced contraction. LY287045 (10(-7) M) attenuated thrombin-induced vasorelaxation, but not vasoconstriction with -log K(B) of 8.4. LY287045 (10(-7) M) also attenuated vasorelaxation, but not vasoconstriction to trypsin, another serine-protease with a thrombin-like catalytic triad, with similar potency (-log K(B) = 8.6) to that for thrombin. Consistent with these vascular effects, LY287045 inhibited the protease activity of both thrombin and trypsin. To explore further the selective inhibitory effect of LY287045 on protease-induced relaxation, we examined the effect of LY287045 on the nitric oxide and prostacyclin pathways and found that LY287045 did not alter vascular responses mediated by nitric oxide or prostacyclin. Likewise, LY287045 did not exert a direct inhibitory effect on the relaxant protease-activated receptor (PAR) since relaxation to the PAR-2-activating peptide was not blocked. The selective effect of LY287045 to inhibit only protease-induced endothelial-dependent relaxation demonstrated that protease inhibition will not affect all protease responses equally. Furthermore, increases in trypsin and thrombin have been associated with inflammation and angiogenesis. To the extent that these findings suggest that LY287045 exhibit dual protease inhibition of endothelial responses, LY287045 may have specific utility in hypotensive inflammatory diseases and in cancer metastases where both trypsin and thrombin have been implicated as causative agents.
凝血酶的活性位点三肽精氨酸抑制剂LY287045被用于研究凝血酶诱导的主动脉舒张和收缩，这两种反应在药理学和生理学上均有所不同。尽管重复给药时凝血酶（10⁻⁷ M）和胰蛋白酶（10⁻⁶ M）会产生快速耐受性，但胰蛋白酶在凝血酶诱导的收缩后会使主动脉收缩。LY287045（10⁻⁷ M）减弱了凝血酶诱导的血管舒张，但对血管收缩没有影响，其-log K(B)为8.4。LY287045（10⁻⁷ M）也减弱了对胰蛋白酶的血管舒张，但对血管收缩没有影响，胰蛋白酶是另一种具有类似凝血酶催化三联体的丝氨酸蛋白酶，其效力与对凝血酶的效力相似（-log K(B) = 8.6）。与这些血管效应一致，LY287045抑制了凝血酶和胰蛋白酶的蛋白酶活性。为了进一步探究LY287045对蛋白酶诱导的舒张的选择性抑制作用，我们研究了LY287045对一氧化氮和前列环素途径的影响，发现LY287045不会改变由一氧化氮或前列环素介导的血管反应。同样，LY287045对舒张性蛋白酶激活受体（PAR）没有直接抑制作用，因为对PAR-2激活肽的舒张反应没有被阻断。LY287045仅选择性抑制蛋白酶诱导的内皮依赖性舒张的作用表明，蛋白酶抑制不会对所有蛋白酶反应产生同等影响。此外，胰蛋白酶和凝血酶的增加与炎症和血管生成有关。就这些发现表明LY287045对内皮反应具有双重蛋白酶抑制作用而言，LY287045在低血压性炎症疾病和癌症转移中可能具有特定用途，在这些疾病中，胰蛋白酶和凝血酶均被认为是致病因素。
