Table 1. Mass spectrometry analysis of sphingomyelin in the biopsies from pigs after inhalation of deuterated d7-sphingosine. Mass spectrometry analysis of the biopsies from pigs that inhaled 3.8 mL of a 125 μM suspension of deuterated d7-sphingosine indicated that inhaled sphingosine reached the trachea and the lung after inhalation of deuterated d7-sphingosine, but is rapidly degraded. Samples were collected post mortem from the pigs 1 h after inhalation of d7 sphingosine. No deuterated sphingosine, sphingosine 1-phosphate or its break-down products (d7-labeled (2E)-hexadecenal, (2E)-hexadecenoic acid or palmitate) were detected in the trachea or lung. We only detected d7-sphingomyelin. Deuterated d7-sphingomyelin was determined in the upper and lower half of the trachea and the lung (Table 1) as well as in spleen, kidney, liver and heart (Table 2). Compared to endogenous levels of sphingomyelin the concentrations of d7-sphingomyelin were very low. Analyzed were 9 samples from the lung, i.e. each 2 or 3 samples per pig and each 4 samples (one from each pig) for the upper and lower half of the trachea, spleen, kidney, liver and heart. Given is the mean SD of each parameter, *p < 0.05, **p < 0.01, ***p < 0.001, ANOVA