Please use this identifier to cite or link to this item: http://hdl.handle.net/10397/65853
Title: cAMP stimulates transepithelial short-circuit current and fluid transport across porcine ciliary epithelium
Authors: Cheng, AKW
Civan, MM
To, CH 
Do, CW 
Keywords: Chloride channel
Ciliary epithelium
Cyclic adenosine monophosphate
Fluid flow
Short-circuit current
Issue Date: 2016
Publisher: Association for Research in Vision and Ophthalmology
Source: Investigative ophthalmology and visual science, 2016, v. 57, no. 15, p. 6784-6794 How to cite?
Journal: Investigative ophthalmology and visual science 
Abstract: PURPOSE. To investigate the effects of cAMP on transepithelial electrical parameters and fluid transport across porcine ciliary epithelium.
METHODS. Transepithelial electrical parameters were determined by mounting freshly isolated porcine ciliary epithelium in a modified Ussing chamber. Similarly, fluid movement across intact ciliary body was measured with a custom-made fluid flow chamber. RESULTS. Addition of 1, 10, and 100 µM 8-Br-cAMP (cAMP) to the aqueous side (nonpigmented ciliary epithelium, NPE) induced a sustained increase in short-circuit current (Isc). Addition of niflumic acid (NFA) to the aqueous surface effectively blocked the cAMP-induced Isc stimulation. The administration of cAMP to the stromal side (pigmented ciliary epithelium, PE) triggered a significant stimulation of Isc only at 100 µM. No additive effect was observed with bilateral application of cAMP. Likewise, forskolin caused a significant stimulation of Isc when applied to the aqueous side. Concomitantly, cAMP and forskolin increased fluid transport across porcine ciliary epithelium, and this stimulation was effectively inhibited by aqueous NFA. Depleting Cl- in the bathing solution abolished the baseline Isc and inhibited the subsequent stimulation by cAMP. Pretreatment with protein kinase A (PKA) blockers (H89/KT5720) significantly inhibited the cAMP- and forskolin-induced Isc responses.
CONCLUSIONS. Our results suggest that cAMP triggers a sustained stimulation of Cl- and fluid transport across porcine ciliary epithelium; Cl- channels in the NPE cells are potentially a cellular site for this PKA-sensitive cAMP-mediated response.
URI: http://hdl.handle.net/10397/65853
ISSN: 0146-0404
EISSN: 1552-5783
DOI: 10.1167/iovs.16-20127
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