title: Acute barrier perturbation abolishes the Ca2+ and K+ gradients in murine epidermis: quantitative measurement using PIXE.
abstract: Epidermal permeability barrier homeostasis requires the delivery of lipids and hydrolytic enzymes by lamellar body exocytosis from the uppermost granular cells, a process that is upregulated following barrier disruption. As lamellar body secretion is controlled by ionic concentrations, especially Ca2+ and K+, we used a quantitative technique, microbeam proton-induced X-ray emission, to measure Ca2+, K+, Cl-, and P concentrations before and after acute barrier perturbation by acetone applications. We found a steep gradient of Ca2+ in normal tissue, peaking in the outer stratum granulosum, which disappeared after barrier disruption, and partially reformed as the barrier recovered. A similar gradient, peaking somewhat lower in the epidermis (i.e., at the stratum granulosum-stratum corneum interface), was found for K+. Epidermal concentrations of K+ also decreased after barrier abrogation, although to a lesser extent than Ca2+. In contrast, P and Cl- demonstrated distribution gradients at baseline, which remained unchanged after barrier disruption. These studies quantitate the levels of Ca2+, K+, Cl-, and P within specific epidermal cell layers at baseline, and in relation to changes in permeability barrier integrity. Ca2+ and K+, but not Cl- or P, decrease after barrier disruption, consistent with these two ion's role in barrier repair.
authors.affiliation: Dermatology Service, Veterans Affairs Medical Center, San Francisco, California 94121, USA.
authors.forename: T
authors.initials: T
authors.lastname: Mauro
authors.forename: G
authors.initials: G
authors.lastname: Bench
authors.forename: E
authors.initials: E
authors.lastname: Sidderas-Haddad
authors.forename: K
authors.initials: K
authors.lastname: Feingold
authors.forename: P
authors.initials: P
authors.lastname: Elias
authors.forename: C
authors.initials: C
authors.lastname: Cullander
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002713:Chlorine / Q000378:metabolism; D004817:Epidermis / Q000378:metabolism*; D008297:Male; D051379:Mice; D008812:Mice, Hairless; D009994:Osmolar Concentration; D010539:Permeability / Q000187:drug effects; D010758:Phosphorus / Q000378:metabolism; D011188:Potassium / Q000378:metabolism*; D013052:Spectrometry, X-Ray Emission
chemical_list: D010758:Phosphorus; D002713:Chlorine; D011188:Potassium; D002118:Calcium