Tachykinins increase respiratory clearance of 99mTc-DTPA. Mechanisms of action.
We investigated the effects of tachykinins on the respiratory clearance of 99mTc-DTPA (RC-DTPA) in anesthetized and ventilated guinea pigs. We measured the change in RC-DTPA and in maximal pulmonary insufflation pressure (PIPmax) induced by substance P, neurokinin A, and capsaicin. Substance P, neurokinin A, and capsaicin increased both PIPmax and RC-DTPA in a concentration-dependent fashion. Substance-P- and capsaicin-induced increases in RC-DTPA were unaffected by pretreatment with atropine. Bilateral vagotomy attenuated substance-P-induced change in both RC-DTPA and PIPmax by approximately 70 and 50%, respectively. Capsaicin-induced change in RC-DTPA and PIPmax were slightly but not significantly reduced by bilateral vagotomy. The bronchodilator, salbutamol, dramatically reduced increase in RC-DTPA and in PIPmax induced by substance P, neurokinin A, and capsaicin, but it had no effect on increases in RC-DTPA and PIPmax generated by application of a positive end-expiratory pressure. We conclude that (1) tachykinins increase respiratory clearance to the solute, and (2) tachykinin-induced increase in RC-DTPA is not mediated by cholinergic neurotransmission but rather by the bronchoconstrictor effect of neuropeptides.
Mordelet-Dambrine
M
M
Service de Pneumologie, Université René Descartes, Hôpital Cochin, Paris, France.
Huchon
G J
GJ
Dusser
D J
DJ
D000420:Albuterol / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D016084:Bronchoconstriction / Q000187:drug effects; D002199:Capillary Permeability / Q000502:physiology; D002211:Capsaicin / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006168:Guinea Pigs; D008168:Lung / Q000000981:diagnostic imaging* / Q000502:physiology; D008297:Male; D011175:Positive-Pressure Respiration; D011650:Pulmonary Alveoli / Q000378:metabolism; D011877:Radionuclide Imaging; D015320:Tachykinins / Q000494:pharmacology*; D016284:Technetium Tc 99m Pentetate; D014628:Vagotomy
D015320:Tachykinins; D001285:Atropine; D000420:Albuterol; D002211:Capsaicin; D016284:Technetium Tc 99m Pentetate