Protective effects of volatile agents against acetylcholine-induced bronchoconstriction in isolated perfused rat lungs.
BACKGROUND
Bronchoactive properties of volatile agents against lung constriction are well established. The purpose of this study was to investigate the ability of halothane (Hal), isoflurane (Iso), sevoflurane (Sev) and desflurane (Des) to alter the lung mechanics in the absence of an airway tone and during acetylcholine (Ach)-induced bronchoconstriction.


METHODS
Low-frequency pulmonary impedance data (ZL) were collected from isolated, normo-perfused rat lungs under baseline conditions and following the injection of Ach (0.1 mg/kg) into the pulmonary artery. Measurements were performed without the administration of any anaesthetic agent in the first phase of the experiments and during inhalation without any volatile agent (control group, n = 6) or during inhalation of Hal (n = 6), Iso (n = 9), Sev (n = 6) or Des (n = 8) at 1 minimum alveolar concentration (MAC). The airway resistance (Raw) and parenchymal damping and elastance were estimated from the Z(L) data by model fitting.


RESULTS
Under baseline conditions, the basic value of Raw was significantly decreased by Des (- 31.2 +/- 3.8%) and Sev (- 18.0 +/- 4.5%) administration, whereas Hal and Iso did not have a statistically significant effect on Raw (- 3.3 +/- 5.1% and - 8.6 +/- 2.4%, respectively). Moreover, all four inhalation anaesthetics prevented the increase in Raw following Ach administration, the findings ranging between - 14.3 +/- 11.4% for Hal and - 37.5 +/- 10.9% for Sev.


CONCLUSIONS
Our results on a denervated isolated perfused lung model demonstrate the potential of Des and Sev to decrease the basal airway tone, whereas Iso and Hal are ineffective in this regard. All of these volatile agents markedly protect against Ach-induced bronchoconstriction.
Lele
E
E
Anaesthesiological Investigations Unit, University of Geneva, Geneva, Switzerland.
Petak
F
F
Fontao
F
F
Morel
D R
DR
Habre
W
W
D000109:Acetylcholine / Q000037:antagonists & inhibitors* / Q000494:pharmacology*; D000403:Airway Resistance / Q000187:drug effects; D000465:Algorithms; D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D016084:Bronchoconstriction / Q000187:drug effects*; D003714:Denervation; D000077335:Desflurane; D006221:Halothane / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects; D066298:In Vitro Techniques; D007530:Isoflurane / Q000031:analogs & derivatives / Q000494:pharmacology; D008168:Lung / Q000187:drug effects*; D008297:Male; D008738:Methyl Ethers / Q000494:pharmacology; D051381:Rats; D015656:Respiratory Mechanics; D000077149:Sevoflurane
D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D000077149:Sevoflurane; D000077335:Desflurane; D007530:Isoflurane; D000109:Acetylcholine; D006221:Halothane