Effect of Tocolytics on Surfactant Secretion When Administered with Betamethasone: An in Vitro Study

Abstract

Objective To analyze the amount of surfactant protein (SP)-B and lecithin/sphingomyelin (L/S) ratio in response to betamethasone (BMS) alone as compared with magnesium sulfate (Mg²⁺), indomethacin (Indo), and nifedipine (Nif) with or without BMS.

Study design NCI-H441 human lung cells were grown and distributed into eight plates. BMS and tocolytics were added and the final plates were: control, BMS only, and each tocolytic ± BMS. Cells were stained with SP-B antibodies and relative fluorescence was measured. Lipids were also extracted, identified, and examined for relative densities. The L/S ratio was calculated.

Results Nine independent measurements were obtained for each plate. The protein analysis revealed that among all eight plates, SP-B levels were highest among BMS only. There was a nonsignificant decrease in SP-B in each of the combinations of tocolytics + BMS as compared with BMS only. Compared with BMS only, L/S ratio was decreased in Mg²⁺ + BMS (p = 0.041), Indo + BMS (p = 0.042), and Nif + BMS (p = 0.025).

Conclusion In our in vitro human lung cell model, SP-B and L/S ratio increased in response to BMS administration alone. The addition of tocolytics to BMS resulted in no increase in L/S ratio and no changes seen in SP-B production compared with BMS alone.

Keywords

tocolytics - surfactant - lecithin - betamethasone - NCI-H441 cell line

This article was presented orally at the 35th Annual Meeting of the Society for Maternal–Fetal Medicine: The Pregnancy Meeting; February 02–07, 2015; San Diego, CA.

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