Alveolar disaturated phospholipids (DSP(A)) increase in vivo in rats with hyperpnea and in isolated perfused lungs (IPL) in response to either salbutamol or increasing tidal volume (VT). Because surfactant protein-A (SP- A) may play a role in surfactant homeostasis, we have examined the relationship between SP-A and DSP in the alveolus lameIlar bodies (LB-A), and in a vesicular (LB-B) lung subfraction. Whereas 2 h swimming increased total DSP(A) (~48%), it had no effect on alveolar SP-A (SP-A(A)). In the IPL, salbutamol increased total DSP(A) (~30% and SP-A(A) (~41%); increasing VT (2.5-fold) only increased DSP(A) (~22%). SP-A and DSP also varied differentially in the tubular myelin-rich and -poor subfractions. In both the IPL and in vivo, we found inverse relationships between DSP(A) and SP- A(A)/DSP(A), indicating that although SP-A(A) and DSPA are related, they vary independently. Whereas total SP-A(A)/DSP(A) varied between 0.046 and 0.074, it remained constant in LB-A (~0.015) and LB-B (~0.010), suggesting that DSP and SPA are secreted differentially and that only a small portion of SP- A(A) is derived from lamellar bodies.
|Number of pages||9|
|Journal||American Journal of Physiology - Lung Cellular and Molecular Physiology|
|Publication status||Published - Sep 1996|
- alveolar surfactant
- isolated perfused lung
- surfactant protein-A