Activation of Vasospasm by X-ray irradiation and hyperventilation.

冠状动脉痉挛的激活。在(1)低胆固醇血症和(2)含2%胆固醇和胆酸钠的饮食诱导的高胆固醇血症下，经球囊导管反复内皮剥脱术和X射线照射后，Gottingen小型猪的左冠状动脉发生了晚期动脉粥样硬化病变。为了阐明X射线照射在血管活性物质增强收缩中的作用，在没有血管内膜损伤的情况下，重复两次X射线照射。在冠状动脉左回旋支或左前降支机械损伤3个月后，冠状动脉内注射5-羟色胺或组胺对损伤部位的收缩作用大于对侧完整部位。剥离5个月后，冠状动脉节段被剥离，X射线照射后比完整部位更严重地收缩为5-羟色胺。因此，我们能够降低痉挛的阈值，增强对5-羟色胺的最大反应。这种增强可以通过静脉注射酮丝氨酸显著减弱。因此，5-羟色胺-2受体的功能可通过X射线照射而改变。在X射线照射后两个月，在未剥离的病例中，10毫克/公斤的5-羟色胺使完整和照射部位分别收缩26&lt；+-3%和45&lt；+-2%(部位间P&lt；0.01)。组织学上观察到X射线照射后动脉内膜增厚。X射线照射本身增强了动脉粥样硬化过程和血管对5-羟色胺的反应性。在呼吸性或代谢性碱中毒情况下，5-羟色胺引起的X射线照射部位的过度收缩从45%增加到76%(p&lt；0.01)。因此，碱中毒激活了动脉硬化血管对痉挛诱导剂的反应性。

Activation of coronary spasm Advanced atherosclerotic lesions were produced along the left coronary artery following repeated endothelial denudation by a balloon catheter and X-ray irradiation in Gottingen miniature pigs under (1) hypocholesterolemia and (2) hypercholesterolemia induced by diet containing 2 % cholesterol and sodium cholate. To elucidate the role of X-ray irradiation in augmented constriction to vasoactive agents, X-ray irradiation was repeated twice with the absence of intimal injury. Responses of the coronary artery to vasoactive agents were evaluated in situ angiographically as changes in luminal narrowing.Three months after mechanical injury of the intima along the left circumflex or left anterior descending coronary artery, intracoronary injection of serotonin or histamine constricted more the injured site than the contralateral intact site. Five months after denudation, coronary segments denuded and X-ray irradiated constricted more severely to serotonin than the intact site. Thus, we were able to reduce the threshold for spasm and to augment the maximal responses to serotonin.Such augmentation was significantly attenuated by intravenous pretreatment with ketanserin. Accordingly, serotonin-2 receptor function may be altered by X-ray irradiation.Two months after X-ray irradiation in cases not denuded, serotonin in a dose of 10 mug/kg constricted the intact and irradiated sites by 26<plus-minus>3 % and 45<plus-minus>2 %, respectively (p<0.01 between sites). Increased intimal thickening was noted histologically along the X-ray irradiated sNamely, X-ray irradiation per se augments both the atherosclerotic process and the responsiveness of the vessel to serotonin. Under respiratory or metabolic alkalosis, serotonin-induced hyperconstriction at the X-ray irradiated site increased from 45% to 76 % (p<0.01). Thus, alkalosis activates the responsiveness of the arteriosclerotic vessel to a spasmogenic agents.