Respiratory Physiology & Neurobiology 142 (2004) 185–195 Persistence of diaphragmatic contraction influences the pulmonary inflammatory response to mechanical ventilation Fabienne Br´ egeon a,∗ , St´ ephane Delpierre a , Antoine Roch b , Osamu Kajikawa c , Thomas R. Martin c , Amapola Autillo-Touati d , Yves Jammes a a Laboratoire de Physiopathologie Respiratoire (EA 2201), Institut Jean Roche, Facult´ e de M´ edecine, Universit´ e de la M´ editerran´ ee, Marseille, France b DAR Hˆ opital Ste Marguerite, Marseille, France c Veterans Affairs Medical Center, Seattle, WA, USA d Laboratoire de Biologie Cellulaire, Institut Jean Roche, Facult´ e de M´ edecine, Universit´ e de la M´ editerran´ ee, Marseille, France Accepted 28 June 2004 Abstract Because we already showed (Br´ egeon, F., Roch, A., Delpierre, S., Ghigo, E., Autillo-Touati, A., Kajikawa, O., Martin, T., Pugin, J., Portugal, H., Auffray, J., Jammes, Y., 2002. Conventional mechanical ventilation of healthy lungs induced pro- inflammatory cytokine gene transcription, Respir. Physiol. Neurobiol. 132, 191–203) that non-injurious mechanical ventilation (MV) elicited inflammatory signal in paralyzed rabbits having normal lungs, we examined the role of neuromuscular blockade in the pulmonary inflammatory response. In the bronchoalveolar lavage fluid (BALF), leukocyte count, MCP-1 and IL-8 cytokine concentrations (ELISA) and mRNAs (reverse transcription polymerase chain reaction, RT-PCR) were measured in paralyzed (P) or non-paralyzed (NP) rabbits ventilated for a 6-h period. Compared to the P group and despite the tidal volume was the same, we measured in the NP one a lower compliance of the respiratory system (Crs,stat), a longer inspiratory time (Ti), a negative inspiratory tracheal pressure (Ptr) wave preceding the pump-induced positive pressure wave, and a higher peak tracheal pressure. Moreover, in NP animals, gross autopsy showed negligible lung abnormalities, and marked reduction of leukocyte count and lung cytokines (P < 0.05). Thus, the absence of neuromuscular blockade decreased the pulmonary chemotactic response to MV suggesting that the total suppression of negative pressure waves elicited by the diaphragmatic (di) contractions could be involved in this lung response to positive pressure MV. © 2004 Elsevier B.V. All rights reserved. Keywords: Mechanical ventilation; Neuromuscular blockade; Diaphragm; Macrophages; Cytokines. ∗ Corresponding author. Tel.: +33 4 91 69 89 25; fax: +33 4 91 69 89 27. E-mail address: fabienne.bregeon@mail.ap-hm.fr (F. Br´ egeon). 1569-9048/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.resp.2004.06.012