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

Leakage of plasma proteins into the alveoli inhibits pulmonary surfactant function and worsens respiratory failure. Surfactant protein B (SP‐B), is essential for surfactant function, but the N‐terminal domain of human SP‐B (residues 1.25, SP‐B 1–25 ) can mimic the biophysical properties of full length SP‐B 1–78 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, fibrinogen was instilled as a surfactant inhibitor, and then they were rescued with exogenous surfactant. Five experimental surfactants were formulated by mixing 3% SP‐B 1–78 , or an equimolar amount of SP‐B 1–25 and/or 1% palmitoylated surfactant protein C (SP‐C) 1–35 , into a standard phospholipid (PL) mixture: B 1–78 , B 1–25 , C 1–35 , B 1–78 +C 1–35 , and B 1–25 +C 1–35 surfactant preparations. Survanta TM was used as a positive control and PL and no treatment as a negative control. Lung function was assessed during a 2‐h period using arterial blood gas and lung compliance measurements. Rats treated with B 1–25 +C 1–35 surfactant and Survanta TM maintained the highest oxygenation and lung compliance values throughout the experiments. The surfactants could be ranked as B 1–25 +C 1–35 surfactant and Survanta TM >B 1–25 and B 1–78 +C 1–35 surfactants >others. Because the N‐terminal domain of surfactant protein B 1–25 can improve inhibition resistance, it may be able to substitute for surfactant protein B in exogenous surfactant preparations.