84: Effect of tocolytic medications on synthesis and secretion of surfactant in an in-vitro human lung cell model

Abstract

84 Effect of tocolytic medications on synthesis and secretion of surfactant in an in-vitro human lung cell model Ziad Haidar, Shamili Sammohi, David Cool, David Mckenna UT HealthUniversity of Texas Medical School at Houston, OB/GYN, Houston, TX, Wright State University, OB/GYN, Dayton, OH OBJECTIVE: To compare the effects of magnesium sulfate, nifedipine, and indomethacin on surfactant synthesis and secretion in adult human lung cells STUDY DESIGN: Human adult lung cells (NCI-H441) were grown to confluence in Waymouth’s MB571/5 medium containing 2% Hyclone and 1.5% Cellgro, containing 10,000 unit/ml penicillin G sodium, 10,000 ug/ml streptomycin sulfate, and 25 ug/ml amphotericin B. The plates were then divided into 4 groups, consisting of three tocolytics and a control. Tissue-equivalent doses of the tocolytics were used to mimic the steady state in-vivo levels of the following doses and routes of administration: indomethacin: 25mg po q6h, nifedipine 10mg po q6h, and magnesium sulfate 2 g/h IV. Betamethasone (BMZ) was added to each group to achieve a comparable tissue concentration to what is achieved clinically when 12 mg IM is given, and then repeated twenty four hours later. Lipids were extracted from the supernatant and separated on anHP-TLC plate in an organic solvent system. The lipids were primuline stained and examined for relative density under a DyLight 488 nmwith a ChemDocMP imaging camera (Bio-Rad, Hercules, CA) from 1 to 10 seconds, and the best image was saved for evaluation. RESULTS: The primuline stained cells showed an increased amount of surfactant B synthesis in each of the combinations: BMZ+nifedipine, BMZ+magnesium, BMZ+indomethacin. Compared to cells containing BMZ alone, the lipid extraction, which is indicative of the cells’ secretion phase, showed a significant increase with BMZ+magnesium and BMZ+indomethacin and decrease with BMZ+nifedipine CONCLUSION: This in-vitro human adult lung cell model demonstrated significant effects on surfactant synthesis and secretion when different tocolytic agents were given along with betamethasone. It is speculated this may be due to intracellular calcium-dependent interactions with the specific tocolytic agents in the type II pneumocytes. Further work is required to illicit the exactmechanism responsible for thesefindings.