Respiratory Tract Eicosanoid Measurement Using Microdialysis Sampling and GC/MS Detection

Abstract Summary: Eicosanoids are important mediators in many physiological and pathophysiological conditions. Sampling the eicosanoids remains a challenge, particularly in the respiratory tract. We examined the possibility that microdialysis might offer a means for sampling the large airways which would provide profiles of local eicosanoid levels before and after challenge. Guinea-pigs were anesthetized by ip injection of urethane and a tracheotomy performed. Microdialysis probes were inserted 2 cm into the tracheal opening, and samples were collected for 1 h intervals over 5 h. Injections of arachidonic acid, leukotriene (LT) D 4 , or saline vehicle were made iv at the beginning of the third hour. Prostaglandins (PG) E 2 , D 2 , F 2α and 6-keto-F 1α and thromboxane (TX) B 2 were determined by GC/MS. Significant post-treatment increases in levels were observed following the injection of arachidonic acid for all eicosanoids except 6-keto-PGF 1α . The greatest change was an 8.1-fold increase for PGD 2 ( P 2 ( P 4 caused significant increases in levels of PGE 2 ( P 2α ( P 1α ( P