Sympathetic neurons modulate plasma extravasation in the rat through a non-adrenergic mechanism.
A blister model of inflammation in the rat hind footpad was used to study the possible interaction between noradrenergic sympathetic fibres and primary afferent unmyelinated fibres which contain substance P (SP), the putative mediator of neurogenic inflammation. Plasma protein extravasation (PE) was used as a measure of the response of post-capillary venules to SP perfused over the blister base. In rats treated with 6-hydroxydopamine (6-OHDA, 75 mg/kg/day for 3 days intraperitoneally) PE was reduced by 42%. However, in rats treated by local perfusion of the blister base with noradrenaline (1 mumol/L) PE was also reduced. As prostaglandins have been postulated to effect some sympathetically mediated responses, PGE1 (1 mumol/L) was perfused over the blister base and found to enhance the response to SP. The results indicate that sympathetic noradrenergic neurones may contribute to SP-induced plasma extravasation by a sensitising mechanism independent of noradrenaline.
Khalil
Z
Z
National Research Institute of Gerontology and Geriatric Medicine, Mount Royal Hospital, Parkville, Vic.
Helme
R D
RD
D000527:Alprostadil / Q000378:metabolism; D000818:Animals; D001768:Blister / Q000503:physiopathology; D006892:Hydroxydopamines; D007249:Inflammation / Q000503:physiopathology; D008297:Male; D009474:Neurons / Q000502:physiology*; D009475:Neurons, Afferent / Q000187:drug effects; D009476:Neurons, Efferent / Q000502:physiology; D009619:Nociceptors / Q000502:physiology; D009638:Norepinephrine / Q000502:physiology; D016627:Oxidopamine; D010146:Pain / Q000503:physiopathology; D010949:Plasma / Q000502:physiology*; D011453:Prostaglandins / Q000096:biosynthesis; D051381:Rats; D011919:Rats, Inbred Strains; D013373:Substance P / Q000494:pharmacology; D013563:Sympathectomy, Chemical; D013564:Sympathetic Nervous System / Q000502:physiology*
D006892:Hydroxydopamines; D011453:Prostaglandins; D013373:Substance P; D016627:Oxidopamine; D000527:Alprostadil; D009638:Norepinephrine