You will be given a definition of a task first, then some input of the task.
In this task, you are given a sentence. You are expected to write the name of the organism substances in the body mentioned in the input. Although there might be several correct answers, you need to write one of them.

 To investigate the potential role of sympathetic nerves in preventing pronounced increases in cerebral blood flow , we evaluated the effects of abrupt hypertension on the cerebral circulation of newborn pigs with intact cerebral sympathetic innervation and after cerebral sympathetic denervation .
Output:
blood