Nonionic polymers reverse inactivation of surfactant by meconium and othersubstances

A variety of substances including human meconium have been found to affect adversely the surface tension-lowering activity of pulmonary surfactants, a nd this effect may be important in the pathogenesis of a number of human di seases. To find whether inactivation of surfactant could be prevented or re duced by nonionic polymers, we added dextrans, polyethylene glycols (PECs), or polyvinylpyrrolidones (PVPs) of various molecular weights to pulmonary surfactants, One to 3% human meconium or other inactivating substances were then added to the mixtures, which were tested in a modified pulsating bubb le surfactometer, Polymers (3.3-500 kD) in 1-10% concentrations enhanced th e ability of a commercial surfactant replacement (Survanta) to lower the mi nimum surface tension in the presence of meconium, serum, or lysophosphatid ylcholine, Similar effects were seen when polymers were added after mixing of surfactant and meconium or other inhibitors, indicating that polymers ar e capable of reversing the inactivation. Results from rat experiments indic ate that total lung capacity is increased when PEC is first added to the Su rvanta, then mixed with meconium and instilled into the lungs. We postulate that polymers separate meconium-surfactant complexes, permitting surfactan t components better access to the air-liquid interface.