It turns out when you give Aldopa to people, it gets converted biochemically into natural dopamine which then serves as its own agonist.

已经证明如果向人体中引入阿多巴,它就能通过生化过程转化为多巴胺,发挥激动剂作用

耶鲁公开课 - 生物医学工程探索课程节选

They can antagonize that reaction, and a result they affect blood rate.

受体阻断剂能够阻断这类作用,进而影响血液流速

耶鲁公开课 - 生物医学工程探索课程节选