Does denervation supersensitivity develop after brain death ?

本实验选用成年猫，雌雄各半，在前庭麻醉下结扎双侧颈内动脉，夹闭椎动脉，造成实验性脑死亡。在比较了几种方法后，我们认为这是因为它的可靠性和简便性。猫在大脑血液循环中断后总是戴着呼吸器。在大脑血液循环中断后，瞳孔逐渐扩大。它适度扩张，大约2小时后固定。反射性瞳孔扩张对坐骨神经的刺激和光反射通常可在此过渡阶段辨认出来。反射性散瞳是广义的纤毛脊髓反射。它在脑死亡完成后消失了。这一结果强烈表明，反射性瞳孔扩张可能是脑死亡的辅助诊断工具。在这个实验中，听觉脑干反应也消失了。在这个实验中，对自主神经药物，在这个实验中是0.125%匹罗卡品，在脑死亡后至少48小时没有被证明是超敏的。在人脑死亡中观察到的超敏反应似乎不是由真正的失神经超敏反应引起的。众所周知，在脑死亡的情况下，脑内的血液循环会中断或几乎停止。因此，我们有理由认为，脑死亡时观察到的超敏反应是由于房水周转延迟或停滞，以及药物在虹膜及其周围组织中积累或代谢延迟所致。

Adult cats both sexs were used in this experiment In order to obtain experimental brain death, the bilateral internal carotid arteries were ligated and the vertebral arteries were clipped under Nembutal anesthesia. We emolyed this because of its reliability and simplicity after comparison of several procedures. Cats were always left on a respirator after discontinuation of blood circulation to the brain.The pupil became gradually dilated after the discontinuation of circulation to the brain. It moderately dilated and fixed around 2 hours later. Reflex pupillary dilatation to the sciatic nerve stimulation and the light reflex usually discernible during this transitional stage. Reflex pupillary dilatation is the ciliospinal reflex in a wide sense. It disappeared after the completion of brain death. This result strongly suggests that reflex pupillary dilatation could be an adjuvant diagnostic tool of brain death. Auditory brainstem response also disappeared in this experiment.Supersensitivity to the autonomic drugs, 0.125% pilocarpine in this experiment, was not proven at least 48 hours after brain death. Supersensitivity observed in human brain death does not appear to be caused by true denervation supersensitivity. It is known that the blood circulation in the brain discontinues or almost ceases under brain death. It is, therefore, reasonable to assume that supersensitivity observed in brain death is due to delay or stasis of the aqueous turnover, and accumulation or metabolic delay of the drugs in the iris and its surrounding tissues.