Pertussis toxin relaxes small arteries with no vascular lesions or vascular smooth muscle cell injury.
Previous studies showed that pertussis toxin (PT) decreased agonist-induced contractions of isolated rat small mesenteric resistance arteries independently from endothelium, nitric oxide-synthase or intracellular calcium concentrations. In this study, it was investigated if the PT-induced decreased contractile properties of small mesenteric resistance arteries could be a consequence of a PT-induced vascular and/or smooth muscle cell injury, leading to loss of contractile functionality. Male Wistar rats were treated with PT (30 microg/kg, intravenously) and sections of isolated small mesenteric resistance arteries were investigated with light- and electron microscopy. Light microscopic investigation of cross-sectioned small mesenteric resistance arteries of control animals clearly showed a contracted phase, while PT-pretreated animals showed a relaxed smooth inner surface of the vessel, indicating a vasodilated state. Electron microscopic investigation showed that PT-pretreatment neither induced vascular lesions nor caused morphological or numerical changes in cell organelles such as contractile elements of vascular smooth muscle cells. In conclusion, the PT-induced decreased contractile properties of isolated rat small resistance arteries are not caused by a PT-induced vascular and/or smooth muscle cell injury.
van Meijeren
Cornelia E
CE
Laboratory of Toxicology, Pathology and Genetics, National Institute for Public Health and the Environment, 3720 BA Bilthoven, The Netherlands. cokky.van.meijeren@rivm.nl
Vleeming
Wim
W
Dormans
Jan A M A
JA
van de Kuil
Ton
T
Opperhuizen
Antoon
A
Hendriksen
Coenraad F M
CF
de Wildt
Dick J
DJ
D000818:Animals; D001886:Bordetella pertussis / Q000737:chemistry; D007275:Injections, Intravenous; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects* / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000648:ultrastructure; D037342:Pertussis Toxin / Q000008:administration & dosage / Q000302:isolation & purification / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D013047:Specific Pathogen-Free Organisms; D014664:Vasodilation / Q000187:drug effects*
D037342:Pertussis Toxin