ABSTRACT
BACKGROUND: Several ions, such as calcium or magnesium ions, are reported to have regulatory effects on epidermal permeability barrier homeostasis. Recently, it has been suggested that strontium ion can play a substitutive role for calcium ion in various cellular reactions. OBJECTIVE: This study was conducted to investigate the effects of strontium ion, either alone or in combination with calcium or magnesium ions, on epidermal permeability barrier homeostasis. METHODS: Female hairless mice were used to study the effects of various ions on epidermal permeability barrier recovery. Calcium chloride solution, magnesium chloride solution or strontium chloride solution were topically applied to barrier-disrupted skin, either alone or simultaneously. Change of transepidermal water loss, which represents permeability barrier function, was measured by TEWameter and morphological change was also observed by light and electron microscopy. RESULTS: Topical application of strontium chloride solution accelerated permeability barrier recovery rate, compared with vehicle-applied skin. Magnesium chloride solution also accelerated barrier recovery rate, as reported in previous studies. Interestingly, simultaneous application of strontium and calcium ions significantly accelerated barrier recovery rate, compared to application of strontium or calcium ion alone. Nile red staining confirmed the increased neutral lipid deposition in strontium ion applied skin. Electron microscopic observation also revealed an increased lamellar body secretion in strontium ion applied skin. CONCLUSION: Strontium ion can play a regulatory role in epidermal permeability barrier homeostasis due to, at least in part, its competitive action on calcium ion for the same ion channel.