A ROLE FOR IONS IN BARRIER RECOVERY AFTER ACUTE PERTURBATION

The epidermal cutaneous permeability barrier can be disrupted by treat ment with topical solvents. Recent studies have shown that barrier rec overy, measured by the recovery of transepidermal water loss towards n ormal, is inhibited by high extracellular Ca++ and K+, and accelerated by low extracellular concentrations of these ions. To examine the eff ects of Ca++ or K+ fluxes on barrier recovery, we tested the effects o n transepidermal water loss recovery of agents that modify these fluxe s. K+ channel agonists or blockers modified the inhibitory effects on barrier recovery induced by raised extracellular Ca++ and K+. In addit ion, Na+/K+ adenosine 5' triphosphatase inhibitors reversed the inhibi tory effects of high extracellular Ca++ and K+. Our results suggest th at barrier recovery requires both Ca++ and K+ fluxes and are consisten t with the hypothesis that both verapamil or dihydropyridine-sensitive Ca++-permeable channels and Ca++ sensitive K+ channels participate in epidermal permeability barrier homeostasis.