Permeability parameters of the toad isolated stratum corneum

Area of Science:

• Dermatology
• Biophysics
• Materials Science

Background:

• The stratum corneum (SC) is the outermost layer of the skin, crucial for barrier function.
• Studying the SC as an isolated membrane is challenging due to its integration with other epidermal layers.

Purpose of the Study:

• To develop and validate a technique for isolating the stratum corneum (SC) as an intact membrane.
• To characterize the biophysical properties of the isolated SC membrane, including electrical resistance and hydraulic conductivity.
• To investigate the ionic transport characteristics and amphoteric nature of the SC.

Main Methods:

• Developed an osmotic shock technique involving immersion in hot distilled water to separate the SC.
• Mounted the isolated SC membrane between half-chambers for electrical resistance and hydraulic filtration coefficient (Lp) measurements.
• Utilized potassium chloride (KCl) diffusion potentials across the SC membrane at varying pH levels to assess ionic transport and determine the isoelectric point.

Main Results:

• The isolated SC membrane exhibited significantly reduced electrical resistance (approx. 1/100 of whole skin) and high hydraulic conductivity (Lp values comparable to whole skin).
• The SC membrane demonstrated amphoteric properties, with an isoelectric pH of 4.6.
• Ionic transport characteristics varied with pH, indicating selective permeability. Divalent cations affected ionic discrimination differently based on membrane charge.

Conclusions:

• The developed osmotic shock technique effectively isolates the stratum corneum (SC) for biophysical and transport studies.
• The isolated SC membrane serves as a valuable model for investigating skin barrier properties and ionic transport mechanisms.
• The SC exhibits distinct electrical, hydraulic, and ionic transport characteristics, influenced by pH and divalent cations.