Objectives: 

Introduction: Beside the key role of the pulmonary surfactant in the alveoli it also has an important function in the physiology of the airways. Aim: The aim of the study was to test the hypothesis that pulmonary surfactant has relaxing effect not only on bronchial but also on extrapulmonary airway smooth muscle and to elucidate the mechanism of this effect.

Materials: 

Methods: In vitro experiments were performed on tracheal strip and pulmonary strip containing bronchial smooth muscle of the adult guinea pigs, placed in the organ chambers. The changes in the tension of strips precontracted by metacholine (control) were evaluated after addition of exogenous surfactant preparations Curosurf (porcine surfactant, Chiesi, Parma, Italy) and Alveofact (bovine surfactant, Lyomarck Pharma, Oberhaching, Germany) and non-selective ion-channels blockers (Glybenclamide and Glyl H101) and were expressed as amplitude of contraction in mN.

Results: 

Both modified natural surfactant preparations had significant relaxing effect on the smooth muscle of intra- and extrapulmonary airways (Curosurf vs.control P  0.05-0.001; Alveofact vs.control P  0.05-0.01) with stronger effect on pulmonary strip. Ion-channels blockers (Na+, K+, Cl-) did not influenced relaxing effect of surfactant.

Conclusions: 

Exogenous surfactant preparations of different origin have relaxing effect on the airway smooth muscle both intra- and extrapulmonary. This effect is probably not mediated through Na+, K+ or Cl- channels.

The study is supported by Centre of experimental and clinical respirology No.26220120034, co-financed from EU sources, and VEGA No.1/0416/12.