Electrical profiles in the corneal epithelium

Abstract

SUMMARY1. The potentials and resistances associated with the cell membranes of the rabbit corneal epithelium were studied with 3 M-KCl-filled microelectrodes.2. In the isolated cornea, the transepithelial potential was identical in polarity and magnitude to the simultaneously measured total cornea] potential. In contrast to previous findings, the stromal potential was positive to the tear side. Negative stromal potentials apparently derive from inadequate electrodes or method of penetration, and were not found to be a function of filling solution. Transepithelial potential was also identical to over-all corneal potential in the living rabbit eye.3. In the isolated preparation, the average potential profile occurred in three distinct steps across the epithelium. By means of iontophoretic dye injection it was shown that these steps occurred across the outer membrane of the squamous cell, the transition region between the wing and basal cell, and across the inner membrane of the basal cell.4. The transverse membrane resistance of the outer epithelial membrane accounted for 60 % of total corneal resistance. As a result, short-circuit current, which depolarizes the cornea, led to a hyperpolarization of the outer membrane, while affecting deeper membrane potentials little or not at all.5. The spontaneous potential of the outer membrane varied inversely with corneal potential in both normal and chloride-free Ringer, while the potential of the inner membrane of the basal cell was relatively constant, approaching the theoretical Nernst potential for potassium. The potential of the outer membrane was at chloride equilibrium and was sensitive to extracellular shunts. A Thevenin equivalent drawn for the epithelium suggested that half of the outer membrane potential could be attributed to

Electric Field–directed Cell Motility Involves Up-regulated Expression and Asymmetric Redistribution of the Epidermal Growth Factor Receptors and Is Enhanced by Fibronectin and Laminin

“…At subepithelial stromal levels, the resistance to current flow was much lower, establishing only a very small lateral fields, wound site negative (Chiang et al, 1992). However, what has not been determined experimentally is the more relevant lateral fields immediately below the upper epithelial layer, where the tight junctons exist and across which the transcorneal PD is established (Klyce, 1972;Wolosin, 1988). Immediately below the migrating surface epithelia, cells are tightly packed, with little extracellular space.…”

Stress-induced corneal epithelial apoptosis mediated by K+ channel activation

“…Tight junctions between neighboring epithelial cells provide a highly resistant junctional barrier with corneal epithelial cells. The integrity of the tight junction is deeded for the corneal epithelial barrier function (Klyce, 1972). It has been demonstrated that corneal epithelial renewal is a continuous process, which is essential for wound healing in the cornea.…”

Stromal lactate accumulation can account for corneal oedema osmotically following epithelial hypoxia in the rabbit.

“…To examine the influence of low 02 tensions on epithelial and stromal thicknesses, corneas were mounted horizontally in a chamber developed previously for micro-electrode experiments (Klyce, 1972). The endothelial and epithelial surfaces were independently perfused with Ringer solution using syringe pumps (Razel,.…”