Sympathetic neuron factors involved in bradykinin-induced plasma extravasation in the rat

Previous studies have demonstrated that bradykinin (BK) produces a sympathetically dependent plasma extravasation into the rat knee joint which is, in part, dependent upon the production of a prostaglandin. In the present study, co-administration of the specific prostaglandin, PGE2, markedly enhanced the BK-induced plasma extravasation. In this study we also report that after chemically induced sympathectomy, by chronic pretreatment with 6-hydroxydopamine (6-OHDA), both the plasma extravasation produced by BK and the enhancing effect of PGE2 are markedly attenuated. Plasma extravasation induced by PGE2 alone was small and was not significantly attenuated by sympathectomy. We conclude that BK-induced extravasation involves production of at least two sympathetic postganglionic neuron (SPGN) terminal-dependent factors, one of which is a cyclo-oxygenase product of arachidonic acid metabolism, probably PGE2, (Coderre et al., J. Neurophysiol., 62 (1989) 45-58) and another that is unidentified.