Penetration of dimyristoylphosphatidylcholine monolayers and bilayers by model beta-blocker agents of varying lipophilicity.

Penetration of model beta-blockers, propranolol, oxprenolol, metaprolol, and nadolol, into dimyristoylphosphatidylcholine (DMPC) monolayers cast on a pH 7.4 phosphate buffer (mu = 0.155 adjusted with NaCl) at 25 degreesC was monitored using a film balance equipped with a Wilhelmy plate for measuring changes in surface pressure.

Dioxygen diffusion in the stratum corneum: an EPR spin label study.

The stratum corneum, the outer 10 microns of the skin, serves as a permeability barrier regulating the transport of molecules between the body and the environment. The purpose of this study is to understand this permeability barrier function as it pertains to the diffusion of molecular oxygen. The stratum corneum was investigated with EPR spectroscopy following inoculation with a stearic acid spin probe.

Dioxygen solubility in aqueous phosphatidylcholine dispersions.

The solubility of molecular oxygen, or dioxygen, in low weight percent (1.5%) sonicated dimyristoylphosphatidylcholine (DMPC) aqueous dispersions saturated with air has been measured as a function of temperature between 10 degrees C and 40 degrees C. A modified Winkler technique was used involving a dual cell coulometric titration with voltammetric endpoint detection in a mixed solvent (methanol/water).

Localization of lipid microdomains and thermal phenomena in murine stratum corneum and isolated membrane complexes: an electron spin resonance study.

The intercellular region of the stratum corneum can be isolated in the form of membrane complexes (intercellular lipids and adjacent cornified envelopes) which are devoid of the cytoplasmic components. In this study the temperature induced phase transitions and corresponding lipid domain reorganization in isolated stratum corneum (SC) sheets and SC membrane complexes (SCM) were determined using the electron spin resonance (ESR) spin probe technique. The spin probe perdeuterated di-tert-butyl nitroxide (pdDTBN) in SC and SCM revealed less well-defined physiologic phase transitions in the SCM and a more polar lipid domain in SC.