[Effect of ambroxol on surfactant secretion and synthesis in isolated type II alveolar cells]

The effect of ambroxol is attributed in part to an effect on surfactant synthesis and secretion. Evidence supporting this hypothesis is largely indirect; a direct effect of ambroxol on surfactant synthesis and secretion remains to be demonstrated. In this study a direct effect of ambroxol was evaluated using isolated alveolar type II cells. Secretion of labelled phosphatidylcholine was measured following the addition of increasing concentrations (10(-8) M to 10(-4) M) of ambroxol to the culture medium for increasing time intervals. There was no significant increase in surfactant secretion with increased ambroxol concentration or prolonged exposure time. Uptake of 3H-choline and synthesis into 3H-phosphatidylcholine was analyzed as an indicator of surfactant synthesis. Again, increasing concentrations of ambroxol (10(-7) M to 10(-5) M) were followed for 1, 2, 4, 8 and 24 h. There was no significant effect on synthesis at any time point. Concentrations higher than those mentioned here resulted in LDH release from cultured cells. Ambroxol which also has anti-oxidative and anti-inflammatory effects does not exhibit direct stimulatory effects on surfactant synthesis and secretion in isolated (rat) alveolar type II cells as has been demonstrated e.g. for beta 2-adrenergic stimulation. A specific pharmacologic way to stimulate the surfactant system remains to be developed.