Comparison of functional efficacy of surfactant protein B analogues in lavaged rats

Leakage of plasma proteins into the alveoli inhibits pulmonary surfactant f unction and worsens respiratory failure. Surfactant protein B (SP-B), is es sential for surfactant function, but the N-terminal domain of human SP-B(re sidues 1.25, SP-B1-25) can mimic the biophysical properties of full length SP-B in vitro. The authors compared the function and inhibition resistance of synthetic surfactant preparations containing SP-B analogues to a natural bovine surfactant preparation "Survanta(TM)". Eight groups of eight rats were lavaged to induce surfactant deficiency, fi brinogen was instilled as a surfactant inhibitor, and then they were rescue d with exogenous surfactant. Five experimental surfactants were formulated by mixing 3% SP-B1-78, or an equimolar amount of SP-B1-25 and/or 1% palmito ylated surfactant protein C (SP- C)(1-35), into a standard phospholipid (PL ) mixture: B1-78, B1-25, C1-35, B1-78+C1-35, and B1-25+C1-35 surfactant pre parations. Survanta(TM) was used as a positive control and PL and no treatm ent as a negative control. Lung function was assessed during a 2-h period u sing arterial blood gas and lung compliance measurements. Rats treated with B1-25+C1-35 surfactant and Survanta(TM) maintained the hi ghest oxygenation and lung compliance values throughout the experiments. Th e surfactants could be ranked as B1-25+C1-35 surfactant and Survanta(TM) > B1-25 and B1-78+C1-35 surfactants >others. Because the N-terminal domain of surfactant protein B1-25 can improve inhib ition resistance, it may be able to substitute for surfactant protein B in exogenous surfactant preparations.