Abstract
Purpose: :
To investigate the mechanism of ion transport across ciliary epithelium of porcine eye, the electrical membrane properties of primary cultures of pigmented ciliary epithelial cells (PE) and non-pigmented ciliary epithelial cells (NPE) were characterized.
Methods: :
The membrane potential of primary culture of PE and NPE cells from porcine eyes was simultaneously measured by an anionic potential-sensitive fluorescent dye, bis(1,3-dibutylbarbituric acid)trimethine oxonol [DiBAC4(3)]. The effects of bathing ion substitution and transporter inhibitors were investigated.
Results: :
The membrane potential of single NPE and PE cells were -69±0.87mV(n=184) and -63±2.08mV(n=105) respectively. All of the single NPE cells, PE cells and Coupling NPE-PE cells showed similar electrical responses towards different bathing solutions and drugs with similar magnitude. Reducing extracellular sodium concentration hyperpolarized the intracellular potential, while chloride replacement caused significant depolarization. Addition of Ba2+ immediately reduced membrane potential. Ouabain also induced depolarization but in a slower manner. A chloride channel blocker, diphenylamine-2-carboxylate (DPC) markedly hyperpolarized intracellular potential, while there showed no effect after the blockage of Na-K-2Cl cotransport by bumetanide.
Conclusions: :
Both the PE and NPE cells from porcine eye possess K+ channel, Na+/K+-ATPase and DPC-sensitive chloride channel. The membrane potential is strongly dependent on the extracellular chloride concentration. The experimental paradigm allows the study of NPE and PE responses simultaneously and may reveal differential transport characteristics of these epithelial cells in orchestrating the aqueous humor production.
Keywords: ciliary body • imaging/image analysis: non-clinical • ion channels