[Pulmonary surfactants: in vivo structure and in vitro biophysical models for investigation and its perspectives].

The metabolism, composition, structure and functions of the alveolar surfactant (AS) are described. The most adequate biophysical models for investigation of AS are considered. The principals and possibilities of three mostly used models are described in details: Monolayers, Spinning drop method and Thin liquid films. Some of the studies of Bulgarian biophysical, physicochemical, biochemical and medical groups on the structure and mechanism of action of AS in vivo using samples of amniotic fluid (AF), animal pulmonary lavages (PL) and tracheal aspirates (TA) of newborns and adults are summarized. The role of specific surfactant proteins (SP-A, SP-B, SP-C and SP-D) on the properties and function of AS is demonstrated. The opportunities of the model investigations for application in laboratory pre- and postnatal diagnosis of the respiratory distress syndrome (RDS), as well as for the efficiency of RDS therapy during exogenous surfactant therapy with ALEC (UK), Survanta (USA), Exosurf (USA), Curosurf (Italy) u Alveofact (Germany) are considered.