Path Dependence of Adsorption Behavior of Mixtures Containing Dipalmitoyl Phosphatidylcholine

Abstract

Summaryor vortexing of a phospholipid mixture of a specific chemical composition may result in an aqueous dispersion of varying he adsorption of aqueous phospholipid dispersions containing composition due to differences in the ease of dispersion of mixture dipalmitoyl phosphatidylcholine (DPPC) is investigated at 35-components. Consequently, a clear probability exists for the for-370C as a preparation technique. Systems mation of variable bulk solution states in lung surfactant replacestudied in terms of surface pressure-time (74) adsorption behavior ment mixtures containing a high % of p~o s p~o~~p~~s~ T-~~~ difwere pure DPPC, 9:1 DPPC:di~almito~l ~~o s~h a~~~~~~t~a~~~~-ferent solution states can exhibit significant surface property difmine, I3 DPPC:egg P~~~P~~~~~Y~~~Y~~~~ (PG), and lipids ex-ferences. This raises the possibility that the therapeutic efficacy of from ' Ow lung lavage. The show that T -~ charac-a specific surfactant replacement mixture will not only be dependteristics can differ significantly depending on the technique by ent upon mixture compos~t~on, concentration, and delivery which the DPPC-containing mixtures are initially dispersed in method (which are currently receiving considerable attention), but 0.15 M NaCl solution. Examples of path dependence include the also upon the solution preparation procedure.fact that DPPC, which will not adsorb at T = 3S0C when placed one surface property that may depend strongly on dispersion in powdered crystals on the subphase surface, exhibits measurable is adsorption.a first step to characterizing the *rr-t changes after subphase dispersion by sonication or by mechan-potential magnitude of such effects on lung surfactant replaceical vortexing. For I 3 DPPC:PG, dispersion by sonication on ice ment, we investigated the adsorption of phospholipid mixtures or by mechanical vortexing gives faster adsorption than dispersion dipahitoyl p~o s p~a t i~y~c~o~~e (DPPC) for a variety by sonication without temperature control. The effect of heating of initial conditions. l-he solution preparation method was the to T = 4s0c, which is greater than the gel to liquid crystal variable in all cases investigated, with subphase ionic composition, temperature of DPPC ( T~ = 410C)9 is found be total surfactant concentration, and subphase temperature held particularly detrimental to the adsorptionof 7:3DPPC:PG. Of the E~~~-~~~ were done for pure DPPC and for the phospholipid mixtures studied, extracted cow lung lipids exhibited mixed systems of 7:3 (molar ratio) D P P C~ by far the greatest adsorption capability and also showed less path (PG) and 9: 1 ~~~~: d i~~l m i t~~l phosphatidylethanolam~ne dependence than I 3 DPPCPG. Similarly, in terms of dispersion (~p p~) , addition, adsorption were on techniques investigated, sonication on ice tended to give the most mixed lipids extracted by chlorofom and methanol from calf lung rapid adsorption for a given phospholipid mixture. lavage. The results support the interpretation that DPPC adsorption from aqueous dispersion differs depe...

Content-dependent activity of lung surfactant protein B in mixtures with lipids

“…Adsorption was measured at 37 Ϯ 0.5°C for surfactant dispersions in a Teflon dish containing a 35-ml buffered subphase (10 mM HEPES, 1.5 mM CaCl2, 150 mM NaCl, pH 7.0) (33,35). The subphase was agitated continuously by a Teflon-coated bar and magnetic stirrer to minimize diffusion resistance.…”

Lung Surfactant Replacement in Premature Lambs with Extracted Lipids from Bovine Lung Lavage: Effects of Dose, Dispersion Technique, and Gestational Age

“…The experiments also address exogenous surfactant dose effects, with tracheal instillation of 15 and 100 mg CLL/kg into lambs at both gestational ages. A final question studied is the effect of CLL dispersion methodology on physiological efficacy, since the surface properties of phospholipid mixtures can be a strong function of lipid dispersion method (8,16). CLL were thus dispersed by the common methods of sonication and mechanical vortexing, and these are shown to lead to dose-dependent differences in enhancing pulmonary function.…”

“…Measurements of surface pressure-time adsorption were made at 35 k 2" C with a sandblasted Wilhelmy slide for CLL dispersed in a 0.15 M NaCl subphase, stirred continuously to remove diffusion resistance (8,16). Adsorption was characterized for CLL dispersed by: 1) vortexiing for 1 h at room temperature (V), and 2) sonication in an ice bath for 1-3 min (S).…”

Adsorption of Natural Lung Surfactant and Phospholipid Extracts Related to Tubular Myelin Formation

“…For in vivo effectiveness, replacement surfactants must have a solution structure which promotes adsorption to the airwater interface after pulmonary delivery. In general, exogenous lung surfactants contain a high percentage of phospholipids, and phospholipid adsorption can be a function of the technique used for dispersion in the aqueous bulk phase (8,13,14). This behavior is related to the ability of phospholipids to form different microstructural states in water, including smectic mesophases and liposomal' aggregates.…”

“…This material, extracted CLL containing approximately 1 % residual protein, reversed surfactant-deficient pressure-volume mechanics in excised lungs ( 19 (8,13,14). Lungs, with trachea and bronchi intact, were lavaged with 3 liters per lung of cool (20" C) 0.15 M NaCl, given in three divided doses.…”