Potassium channel openers accelerate epidermal barrier recovery.

BACKGROUND

Maintenance of a competent permeability barrier in the face of external and internal stressors requires signals between the stratum corneum interface and the metabolic machinery in the underlying nucleated layers. For example, reductions in the ion gradients for Ca2+ after acute barrier disruption stimulate lamellar body (LB) secretion, a response required to restore barrier homeostasis. Although alterations in external K+ levels also regulate barrier recovery after acute insults, the mechanisms whereby K+ regulates barrier function remain unknown.

OBJECTIVES

To evaluate effects of regulators of K+ channels on barrier homeostasis in hairless mice.

METHODS

We tested a number of chemically different drugs that alter intracellular K+ levels. Results Single applications of either K+ channel openers (i.e. 1-EBIO, minoxidil, diazoxide) or the K+ ionophore, valinomycin, accelerated barrier recovery after acute insults to murine skin, paralleled by a reduction in intracellular K+ levels in cultured human keratinocytes. In contrast, applications of K+ channel blockers (i.e. gilbenclamide, dequalinium) delayed barrier recovery. Alterations in intracellular K+ regulated barrier homeostasis by either stimulating (reduced K+) or inhibiting (elevated K+) LB secretion. Finally, development of epidermal hyperplasia, a downstream consequence of barrier disruption, was also inhibited by agents that reduce intracellular K+ levels.

CONCLUSIONS

These results demonstrate that changes in K+ levels that can be presumed to occur after barrier disruption signal metabolic responses, i.e. LB secretion, which accelerates normalization of barrier function.