Abstract
Abstract: :
Purpose: To determine net chloride secretion by in vitro porcine ciliary body epithelium (CBE) preparation in modified Ussing chamber. The effect of heptanol on the net chloride secretion was also studied. Methods: Freshly isolated porcine CBE tissues were mounted in modified Ussing chambers (aperture area: 10mm2) with continuous perfusion of Ringer solution. The electrical parameters: potential difference (PD), short-circuit current (SCC), and electrical resistance (R) were continuously monitored. Paired preparations from the same eye with comparable electrical parameters were used in the study. The stromal-to-aqueous (Jsa) and the aqueous-to-stromal (Jas) chloride fluxes were measured. 3[H] L-glucose flux, which indicated paracellular leakage was also measured. Results: Net chloride secretion by porcine CBE was found to be 0.88±0.19 µEqhr-1cm-2 (mean±SEM, n=7). The Jsa was 3.62±0.20 µEqhr-1cm-2 while the Jas was 2.74±0.15 µEqhr-1cm-2. The Jsa was significantly larger than the Jas (Paired-t test, p <0.01). Bilateral application of a gap junction blocker, heptanol (0.05% in 0.1% DMSO), reduced the net chloride secretion by 86% (Unpaired t-test, p<0.05, n=5). Conclusions: We have identified a net chloride secretion across the porcine ciliary epithelium. It may be a driving force for the aqueous humor formation in pig eye. The inhibitory effect of heptanol suggested that the net chloride secretion was transcellular in nature.
Keywords: aqueous • inflow/ciliary body • animal model