Bradykinin and cerebral circulation: selective non-receptor interaction with histamine and serotonin through the system of nitric oxide.

Bradykinin, histamine and serotonin were the most active physiological agonists in increasing jugular levels of nitric oxide when administered into the left common carotid artery of anaesthetized rabbits. Bradykinin potentiated selectively the effects of histamine and serotonin (but not vice versa) on both nitric oxide and carotid blood flow, without involving activation of specific receptors. Since these effects were demonstrated using doses of the three agonists in the order of their physiological plasma concentrations, it was concluded that cerebral circulation in regulated, also within its autoregulatory limits, by bradykinin through selective autocoidal interactions converging on nitric oxide.