Simonato M.,University of Padua |
Baritussio A.,University of Padua |
Pioselli B.,Corporate Preclinical RandD |
Ori C.,University of Padua |
And 3 more authors.
Analytical and Bioanalytical Chemistry | Year: 2014
Surfactant protein C (SP-C) is deemed as the surfactant protein most specifically expressed in type II alveolar epithelial cells and plays an important role in surfactant function. SP-C turnover in humans and its meaning in the clinical context have never been approached. In this study, we used mass spectrometry to investigate SP-C turnover in humans. We studied four infants and eight adults requiring mechanical ventilation. All patients had no lung disease. Patients received a 24-h continuous infusion of 13C-leucine as precursor of SPC, and serial tracheal aspirates and plasma samples were obtained every 6 h till 48 h. SP-C was isolated from tracheal aspirates by sorbent-phase chromatography. 13C-leucine SP-C enrichment could be successfully measured in three infant and in four adult samples by using mass spectrometry coupled with a gas chromatographer. Median SP-C fractional synthesis rate, secretion time, and peak time were 15.7 (14.1-27.5) %/ day, 6.0 (4.7-11.5) h, and 24 (20-27) h. In conclusion, this study shows that it is feasible to accurately determine SP-C turnover in humans by stable isotopes. © Springer-Verlag Berlin Heidelberg 2014.