A universal steady state I-V relationship for membrane current

Negative electric potential induces alteration of ion gradient and lamellar body secretion in the epidermis, and accelerates skin barrier recovery after barrier disruption

Previous reports suggested that ion gradients of ions such as calcium and magnesium in the epidermis play a crucial part in skin barrier homeostasis. We hypothesized that external electric potential affects the ionic gradient and skin barrier homeostasis. We demonstrated here that application of a negative electric potential (0.50 V) on hairless mice skin accelerated the barrier recovery approximately 60.7% of the original level within 1 h compared with control (37.5%) after barrier disruption by acetone treatment. Even after the application of a negative potential, the skin showed accelerated repair for 6 h. On the contrary, the skin that was applied a positive potential for 1 h showed a significant delay in barrier recovery (25.3%) than the control. Ultrastructural studies by electron microscopy suggested that the extent of lamellar body exocytosis into the stratum corneum/stratum granulosum interface increased under a negative potential. Magnesium and calcium ion concentrations in the upper epidermis were relatively higher in the negative portion than in the portion where the positive potential was applied. Topical application of these ions on mice skin also accelerated the barrier recovery. These results suggest that the external electric potential affects the ionic gradients in the epidermis and also influences the skin barrier homeostasis.

A lattice relaxation algorithm for three-dimensional Poisson-Nernst-Planck theory with application to ion transport through the gramicidin A channel

A lattice relaxation algorithm is developed to solve the Poisson-Nernst-Planck (PNP) equations for ion transport through arbitrary three-dimensional volumes. Calculations of systems characterized by simple parallel plate and cylindrical pore geometries are presented in order to calibrate the accuracy of the method. A study of ion transport through gramicidin A dimer is carried out within this PNP framework. Good agreement with experimental measurements is obtained. Strengths and weaknesses of the PNP approach are discussed.