Mechanism of Water Binding in Stratum Corneum

Abstract

SUMMARY.— The results presented in this paper confirm the published observations by others that the hygroscopic water‐soluble substances within the corneum are responsible for much of the water binding ability of the horny layer. The ability of corneum to bind water is reduced when it is extracted with solvents, which remove lipid, and then with water, which removes the water‐soluble substances. Our interpretation of this is that the water‐soluble substances are retained within the corneum by a lipid‐containing semipermeable membrane system which allows these substances to take up water by osmosis and protects them from dissolution when the intact corneum is immersed in water. Our experiments show that isolated corneum from guinea‐pig footpads and from human palms, soles and abdomen can take up and lose water by osmosis. Powdering the corneum allows water to extract the water‐soluble substances without a prior solvent extraction. The powdering procedure ruptures the cell walls of the corneum cells and we propose that it is the cell walls which make up the lipid containing semi permeable membrane system. A method for measuring extensibility of isolated strips of corneum in a humid atmosphere has been developed. Using this technique it has been shown that it is the water held by the water‐soluble substances that is responsible for most of the extensibility of corneum.

Relationship Between NMF (Lactate and Potassium) Content and the Physical Properties of the Stratum Corneum in Healthy Subjects

“…In previous in vitro studies, treatments with ether and water significantly reduced the water binding of the SC of guinea-pig footpad (Middleton, 1968), as well as the elasticity of the SC of the back skin of pig (Jokura et al, 1995). In our study on healthy subjects, we confirmed that the extraction of NMF from the SC decreased the SC hydration and increased the SC stiffness and pH.…”

Do Urea and Sodium Chloride together Increase the Efficacy of Moisturisers for Atopic Dermatitis Skin?

“…However, scientific evidence, in addition to clinical experience, is needed to increase the understanding of how emollients cause their effects. The publications of Blank [1] and Middleton [2] initiated an era of increased understanding of the significance of water for skin functions in various dermatological and cosmetic conditions. Later improvements in moisturisers were made by Hagströmer/Nyrén/Emtestam adding active substances, such as urea, lactic acid and sodium chloride [3,4].…”

Effect of 2‐hydroxyacids on guinea‐pig footpad stratum corneum: mechanical properties and binding studies

“…The correlation between the mechanical properties of stratum corneum and its water binding is well documented (4). The fact that 2-hydroxycaprylic acid can increase the extensibility of normal guinea-pig footpad stratum corneum cannot, however, be attributed to increased water binding.…”

“…Middleton (4) described a useful method to investigate the physical properties of stratum corneum by measuring the extensibility of the corneum on an Instron Tester, and described a relationship between the water content of the corneum and the degree of extensibility. He showed that lactic acid increased both the extensibility of solvent-damaged corneum and its water content (4). This paper is an extension of Middleton's work (2,4) and compares the effect of lactic acid with its longer-chained analogues (2-hydroxyacids) on the extensibility of undamaged and solvent-damaged stratum corneum excised from guinea-pig footpads.…”