MacLennan S J, McGrath J C, Whittle M J
Autonomic Physiology Unit, The University, Glasgow, Schotland.
Prostaglandins. 1988 Nov;36(5):711-29. doi: 10.1016/0090-6980(88)90015-9.
In this study we have quantified the potency of three cyclo-oxygenase inhibitors, indomethacin, flurbiprofen and aspirin to reduce the vasoconstriction of isolated strips of human umbilical artery (HUA) to changing the oxygen-tension (PO2) of the bathing medium. The inhibitory potencies (IC50) of indomethacin and flurbiprofen were similar (IC50 = 2.1 x 10(-9) M and 7.6 x 10(-9) M respectively) while aspirin (IC50 = 2.5 x 10(-5) M) was approximately 12,000 fold less potent than indomethacin. At the physiological PO2 of 15 mmHg the isolated HUA was found to have an inherent cyclo-oxygenase induced tone since either reducing the PO2 from 15 to OmmHg or adding cyclo-oxygenase inhibitors caused vasorelaxation. O2-induced contractions were partly dependent on extracellular Ca2+: nifedipine and Bay K 8644 inhibited and enhanced oxygen-induced contractions, respectively, but did not have a significant effect on calcium-dependent 5-hydroxy-tryptamine-induced (5-HT) contractions. Therefore cyclo-oxygenase products and 5-hydroxytryptamine-induced contractions of the HUA may both utilise extracellular calcium but through different processes.
在本研究中，我们通过改变浴液的氧张力（PO2），对三种环氧化酶抑制剂吲哚美辛、氟比洛芬和阿司匹林降低人脐动脉（HUA）离体条带血管收缩作用的效能进行了量化。吲哚美辛和氟比洛芬的抑制效能（IC50）相似（分别为IC50 = 2.1×10(-9)M和7.6×10(-9)M），而阿司匹林（IC50 = 2.5×10(-5)M）的效能比吲哚美辛低约12,000倍。在生理PO2为15 mmHg时，发现离体HUA具有内在的环氧化酶诱导张力，因为将PO2从15 mmHg降至0 mmHg或添加环氧化酶抑制剂均可引起血管舒张。氧诱导的收缩部分依赖于细胞外Ca2+：硝苯地平和Bay K 8644分别抑制和增强氧诱导的收缩，但对钙依赖性5-羟色胺诱导的（5-HT）收缩无显著影响。因此，环氧化酶产物和5-羟色胺诱导的HUA收缩可能都利用细胞外钙，但通过不同的过程。
