Acute radiation-induced vomiting in area postrema-ablated cats.
Acute radiation-induced vomiting in area postrema-ablated cats.
复制标题
后雷马消融区猫的急性辐射诱发呕吐。
作者：
H. Borison;L. McCarthy;E. Douple;J. Johnson;R. Borison
正常未麻醉猫在全身暴露于7.5和90戈伊之间选定剂量的60 Co辐射后24 h内，呕吐发生率、呕吐发作潜伏期和呕吐活动持续时间均呈剂量-反应关系。每次呕吐，即，通过几天前插入到上级腔静脉中的导管，通过X线摄影记录其特征性胸内压力波形。45戈伊的γ-辐射剂量诱发呕吐最佳的发病率为92%，平均发病时间为98分钟。当给药的动物准备长期手术消融的最后区，相同剂量的辐射诱发呕吐的五个测试案例中的四个，平均发病时间，这是不是由任何一个措施显着不同正常。6只正常猫在头部被屏蔽的情况下接受45戈伊的X射线肠内照射，也引起呕吐。同样形式的辐射诱发呕吐的三个慢性postremectomized猫。通过注射洋地黄的呕吐不应性确定最后区的成功消融功能，并通过组织学检查确认完整性。它的结论是，最后区是不是辐射诱发呕吐的反射机制中的一个基本要素，因此，没有生理基础存在依赖于一个中央作用的化学因子在放射性呕吐。
A dose-response relationship was established in normal unanesthetized cats for emetic incidence, latency to onset of vomiting, and duration of emetic activity over a period of 24 h after whole-body exposure to 60Co radiation at selected doses between 7.5 and 90 Gy. Each episode of vomiting, i.e., retching and expulsion, was recorded oscillographically as its characteristic intrathoracic pressure waveform by means of a catheter inserted some days before into the superior vena cava. The gamma-radiation dose of 45 Gy evoked vomiting optimally with an incidence of 92% and an average onset time of 98 min. When administered to animals prepared chronically with surgical ablation of the area postrema, the same dose of radiation evoked vomiting in four of five test cases and with an average time to onset that was not by either measure significantly different from normal. Vomiting was also elicited in all of six normal cats exposed to an intestinal dose of 45 Gy X radiation with the head shielded. The same form of irradiation evoked vomiting in two of three chronically postremectomized cats. Successful ablation of the area postrema was determined functionally by emetic refractoriness to an injection of digitalis and confirmed for completeness by histological examination. It is concluded that the area postrema is not an essential element in the reflex mechanism of radiation-induced vomiting and, therefore, no physiological basis exists for dependence on a centrally acting chemogenic factor in radioemesis.