cAMP stimulates transepithelial short-circuit current and fluid transport across porcine ciliary epithelium

Angela King Wah Cheng, Mortimer M. Civan, Chi Ho To, Chi Wai Do

Research output: Journal article publicationJournal articleAcademic researchpeer-review

1 Citation (Scopus)

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 Iscstimulation. The administration of cAMP to the stromal side (pigmented ciliary epithelium, PE) triggered a significant stimulation of Isconly at 100 µM. No additive effect was observed with bilateral application of cAMP. Likewise, forskolin caused a significant stimulation of Iscwhen 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 Iscand inhibited the subsequent stimulation by cAMP. Pretreatment with protein kinase A (PKA) blockers (H89/KT5720) significantly inhibited the cAMP- and forskolin-induced Iscresponses. 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.
Original languageEnglish
Pages (from-to)6784-6794
Number of pages11
JournalInvestigative Ophthalmology and Visual Science
Volume57
Issue number15
DOIs
Publication statusPublished - 1 Dec 2016

Keywords

  • Chloride channel
  • Ciliary epithelium
  • Cyclic adenosine monophosphate
  • Fluid flow
  • Short-circuit current

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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