A brief exposure to isoflurane (50 s) significantly impacts on plasma cytokine levels in endotoxemic rats

Induction of anesthesia by inhalation of isoflurane is a frequently used procedure in models of immunological diseases. Here we investigated effects of a brief exposure to isoflurane on cytokine production by endotoxemic rats. Anesthesia was either performed by pentobarbital/fentanyl without or accompanied by a 50-s inhalation pretreatment with isoflurane. After 4 h of endotoxemia, plasma levels of TNFα, IL-1β, and RANTES were determined. Isoflurane significantly inhibited plasma levels of TNFα and IL-1β by 69.3% and 61.8%, respectively. Levels of RANTES were similarly reduced by 43.1% (n.s.). Moreover, isoflurane significantly attenuated basal nitrite production by alveolar macrophages isolated from endotoxemic rats (by 59.4%). Thus, we confirm anti-inflammatory properties of isoflurane and beyond that clearly demonstrate that even a short exposure (< 1 min) can profoundly affect pro-inflammatory parameters in experimental endotoxemia. These unforeseen observations suggest that short-term inhalation of isoflurane for induction of anesthesia may be an unsuitable procedure particularly in animal models of acute inflammation.