Role of the cholinergic pathway in mediating platelet-activating factor-induced pulmonary dysfunctions in unsedated calves.
The purpose of this study was to investigate the possible role of the cholinergic pathway in mediating platelet-activating factor (PAF)-induced pulmonary dysfunctions in unsedated calves. In a placebo group, PAF infusion challenge induced significant dysfunctions in the pattern of breathing [a significant increase in respiratory rate (RR) and a significant decrease in tidal volume (VT)], the mechanics of breathing [a significant increase in total lung resistance (RL) and a significant decrease in dynamic lung compliance (CLdyn)] and gas exchange, whereas in atropine pre-treated calves, PAF infusion challenge induced a significant increase in RR, VT and HR and a significant decrease in CLdyn. The RL increase was prevented by atropine pre-treatment. On the basis of our findings, we suggest that, in cattle, the PAF-induced pattern of breathing dysfunctions and the diffuse bronchoconstriction and microvascular leakage of small airways are not mediated through the cholinergic pathway. By contrast, our data suggest that PAF-induced bronchoconstriction of upper airways is at least partly mediated through muscarinic receptors.
Van de Weerdt
M L
ML
Laboratory for Functional Investigation, Faculty of Veterinary Medicine, University of Liège, Belgium.
Husson
C
C
Lekeux
P
P
D000818:Animals; D016084:Bronchoconstriction / Q000187:drug effects / Q000502:physiology*; D002417:Cattle; D006339:Heart Rate / Q000187:drug effects; D007262:Infusions, Intravenous; D008168:Lung / Q000187:drug effects* / Q000502:physiology; D008297:Male; D010972:Platelet Activating Factor / Q000008:administration & dosage / Q000494:pharmacology*; D011976:Receptors, Muscarinic / Q000502:physiology; D012129:Respiratory Function Tests / Q000662:veterinary; D015656:Respiratory Mechanics / Q000187:drug effects / Q000502:physiology*; D013990:Tidal Volume / Q000187:drug effects
D010972:Platelet Activating Factor; D011976:Receptors, Muscarinic