Plasma extravasation induced in rat trachea by 6-OHDA is mediated by sensory nerves, not by sympathetic nerves.
6-Hydroxydopamine (6-OHDA) stimulates the release of catecholamines from sympathetic nerves. This stimulation has been proposed as the basis of the 6-OHDA-induced increase in vascular permeability in the rat knee joint. We sought to determine whether 6-OHDA increases vascular permeability in the rat trachea through a similar mechanism. We also sought to determine whether sympathetic nerves contribute to the plasma extravasation caused by stimulating sensory nerves with capsaicin. In anesthetized rats, an intratracheal infusion of 6-OHDA caused more Monastral blue extravasation than did an infusion of vehicle (area density, 23 +/- 3% vs. 9 +/- 1%). Chemical sympathectomy, which reduced the number of tyrosine hydroxylase-immunoreactive nerves by 98%, did not reduce the amount of extravasation induced by 6-OHDA. However, pretreatment with capsaicin, which reduced the number of substance P-immunoreactive nerves by 95%, reduced the Monastral blue extravasation induced by 6-OHDA by 98%. Extravasation induced by stimulating sensory nerves with capsaicin was not significantly different in tracheae with or without sympathetic nerves. We conclude that in the rat trachea infusion of 6-OHDA causes plasma extravasation by stimulating sensory nerves, not by stimulating sympathetic nerves. Furthermore, sympathetic nerves are not essential for the plasma extravasation induced by capsaicin.
Sulakvelidze
I
I
Cardiovascular Research Institute, University of California, San Francisco 94143-0130.
Baluk
P
P
McDonald
D M
DM
D000818:Animals; D002199:Capillary Permeability / Q000187:drug effects*; D002211:Capsaicin / Q000494:pharmacology; D007150:Immunohistochemistry; D008297:Male; D009424:Nervous System Physiological Phenomena; D016627:Oxidopamine / Q000494:pharmacology*; D010949:Plasma / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D012677:Sensation; D013563:Sympathectomy, Chemical; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology*; D014132:Trachea / Q000098:blood supply* / Q000378:metabolism; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
D016627:Oxidopamine; D014446:Tyrosine 3-Monooxygenase; D002211:Capsaicin