Wang Z, Gurel O, Weinbach S, Notter R H
Department of Pediatrics, University of Rochester, New York 14642, USA.
Am J Respir Crit Care Med. 1997 Oct;156(4 Pt 1):1049-57. doi: 10.1164/ajrccm.156.4.96-10077.
The relative contributions of zwitterionic and anionic phospholipids to the surface-active function of calf lung surfactant extract (CLSE) were assessed by measurements of surface properties in vitro and pressure-volume (P-V) mechanics in excised rat lungs in situ. Surface activity and mechanical effects were compared for chromatographically purified CLSE subfractions containing the complete mix of phospholipids (PPL) or modified phospholipids depleted in anionic components (mPPL), alone or combined with 1.3% (by weight) of hydrophobic surfactant proteins (SP-B and SP-C). Surface pressure-time (pi-t) adsorption isotherms at 37 degrees C were very similar for dispersions of PPL and mPPL in a Teflon dish with a stirred subphase to minimize diffusion resistance. Combination of either PPL or mPPL with hydrophobic SP substantially improved adsorption, but mixtures of PPL:SP and mPPL:SP had only small differences in pi-t isotherms and reached the same final equilibrium pi of approximately 47 mN/m achieved by CLSE. Surface pressure-area (pi-A) isotherms and maximum surface pressures were also very similar for spread films of PPL versus mPPL and PPL:SP versus mPPL:SP on the Wilhelmy balance (23 degrees C and 37 degrees C). Respreading based on pi-A isotherm area calculations was slightly better in surface-excess films of PPL versus mPPL and PPL:SP versus mPPL:SP, but differences were minor and were smaller at 37 degrees C than at 23 degrees C. Overall dynamic surface activity in oscillating bubble studies was not significantly different for PPL versus mPPL or for PPL:SP versus mPPL:SP, and the latter two mixtures both reached minimum surface tensions < 1 mN/m (37 degrees C, 20 cycles/min, 0.5 mM phospholipid). Dispersions of PPL:SP, mPPL:SP, and CLSE were also not significantly different in improving P-V mechanics almost to normal when instilled in lavaged, excised rat lungs at 37 degrees C (30 mg/2.5 ml saline). These data suggest that zwitterionic phospholipids have a major role over anionic phospholipids in interacting with hydrophobic SP in the adsorption, dynamic surface tension lowering, film respreading, and pulmonary mechanical activity of the hydrophobic components of calf lung surfactant in CLSE.
通过体外测量表面性质以及原位测量切除的大鼠肺脏的压力-容积（P-V）力学，评估了两性离子磷脂和阴离子磷脂对小牛肺表面活性剂提取物（CLSE）表面活性功能的相对贡献。比较了含有完整磷脂混合物（PPL）或阴离子成分减少的修饰磷脂（mPPL）的色谱纯化CLSE亚组分单独或与1.3%（重量）的疏水表面活性剂蛋白（SP-B和SP-C）组合时的表面活性和力学效应。在37℃下，PPL和mPPL在带有搅拌亚相的聚四氟乙烯培养皿中的分散体的表面压力-时间（π-t）吸附等温线非常相似，以最小化扩散阻力。PPL或mPPL与疏水SP的组合显著改善了吸附，但PPL:SP和mPPL:SP混合物的π-t等温线只有微小差异，并且达到了与CLSE相同的约47 mN/m的最终平衡π。在威尔海姆天平上（23℃和37℃），PPL与mPPL以及PPL:SP与mPPL:SP的铺展膜的表面压力-面积（π-A）等温线和最大表面压力也非常相似。基于π-A等温线面积计算的再铺展在PPL与mPPL以及PPL:SP与mPPL:SP的表面过剩膜中略好，但差异很小，并且在37℃时比在23℃时更小。在振荡气泡研究中，PPL与mPPL或PPL:SP与mPPL:SP的总体动态表面活性没有显著差异，并且后两种混合物在37℃（20次循环/分钟，0.5 mM磷脂）时均达到最小表面张力<1 mN/m。当在37℃下将PPL:SP、mPPL:SP和CLSE的分散体注入灌洗过的切除大鼠肺脏（30 mg/2.5 ml盐水）时，它们在改善P-V力学几乎恢复正常方面也没有显著差异。这些数据表明，在CLSE中小牛肺表面活性剂疏水成分的吸附、动态表面张力降低、膜再铺展和肺力学活性方面，两性离子磷脂在与疏水SP相互作用中比阴离子磷脂起主要作用。
