April 2011
Volume 52, Issue 14
Free
ARVO Annual Meeting Abstract  |   April 2011
Modulation Of Chloride Transport And Aqueous Humor Secretion By Baicalein
Author Affiliations & Notes
  • Jingru Xiao
    Laboratory of Experimental Optometry, School Of Optometry, Hong Kong Polytechnic University, Hong Kong, Hong Kong
  • King Kit Li
    Laboratory of Experimental Optometry, School Of Optometry, Hong Kong Polytechnic University, Hong Kong, Hong Kong
  • Wai Shun Tam
    Laboratory of Experimental Optometry, School Of Optometry, Hong Kong Polytechnic University, Hong Kong, Hong Kong
  • Chi Wai Do
    Laboratory of Experimental Optometry, School Of Optometry, Hong Kong Polytechnic University, Hong Kong, Hong Kong
  • Chi Ho To
    Laboratory of Experimental Optometry, School Of Optometry, Hong Kong Polytechnic University, Hong Kong, Hong Kong
    State Key Laboratory of Ophthalmology, Department of Ophthalmology, Sun Yat-sen University, Guangzhou, China
  • Footnotes
    Commercial Relationships  Jingru Xiao, None; King Kit Li, None; Wai Shun Tam, None; Chi Wai Do, None; Chi Ho To, None
  • Footnotes
    Support  glaucoma niche(Polyu, J-BB76), GRF B-Q04F, 1-BB8W( PolyU)
Investigative Ophthalmology & Visual Science April 2011, Vol.52, 1519. doi:
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      Jingru Xiao, King Kit Li, Wai Shun Tam, Chi Wai Do, Chi Ho To; Modulation Of Chloride Transport And Aqueous Humor Secretion By Baicalein. Invest. Ophthalmol. Vis. Sci. 2011;52(14):1519.

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Abstract

Purpose: : Baicalein is a flavonoid derived from the root of the medicinal herb Scutellaria baicalensis. It has been widely used in China for its multiple biological functions (e.g. anti-inflammatory, anti-tumor). Besides, baicalein has also been found to regulate chloride secretion in some epithelial cells. The aims of this study are to determine whether baicalein (1) affects the Cl- and fluid transport across the ciliary epithelium and (2) inhibits the aqueous humor formation.

Methods: : The intracellular chloride concentration ([Cl-]i) in primary cultures of non-pigmented ciliary epithelial cells(NPE) from porcine eyes was measured by the fluorescent dye, N-[ethoxycarbonylmethyll-6-methoxy-quinolinium bromide(MQAE). Fresh porcine ciliary body/epithelium preparation was excised and mounted in a custom-made chamber for the simultaneous measurement of transepithelial electrical parameters and fluid movement. The aqueous humor formation rate was determined based upon the rate of fluorescein dilution in the anterior chamber of an isolated arterially-perfused eyes.

Results: : The intracellular Stern-Volmer constant K was calculated to be 20±0.55 M-1(Mean±SEM, from 3 independent calibration experiments). 100µM baicalein raised the intracellular chloride level of NPE by 77%±10% (n=4), while 0.1% DMSO caused no significant change in the controls (n=3, p>0.05). In excised ciliary epithelium, addition of 100µM baicalein to the aqueous side caused a simultaneous inhibition of both transepithelial potential difference and fluid transport into the eye by 51%± 4% (n=10) and 31% ±7% (n=6) respectively. Moreover, baicalein significantly reduced the aqueous humor formation rate by 10%± 3% (n=15) when added to the anterior chamber of the perfused eye.

Conclusions: : Our results show that baicalein reduces the Cl- and fluid secretion across the ciliary epithelium, thereby slowing the rate of aqueous inflow. These effects were possibly mediated by the inhibition of Cl- channels in non-pigmented ciliary epithelial cells, which was consistent with the chloride accumulation induced by baicalein.

Keywords: ciliary body • imaging/image analysis: non-clinical • electrophysiology: non-clinical 
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