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| Effect of cAMP on Porcine Ciliary Transepithelial Short-Circuit Current, Chloride and Sodium Transport |
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| 作者：吴仁毅, … 文章来源：浙江大学医学院附属二院眼科中心 点击数1486 更新时间：2005/6/8 11:04:39 文章录入：majin 责任编辑：毛进 |
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| PURPOSE. To primarily investigate whether 8-bromo-cAMP (cAMP) evokes short-circuit current (Isc) changes that are associated with Na+ or Cl- transepithelial transport in isolated porcine ciliary processes and/or epithelium bilayer. METHODS. With an Ussing-type chamber, transepithelial Isc, potential different (PD), 22Na+, and/or 36Cl- fluxes induced by cAMP were measured. Drugs were applied either on the non-pigmented epithelium (NPE) or pigmented epithelium (PE) side. RESULTS. At baseline, net PE-to-NPE transepithelial 36Cl- (0.07 ± 0.03 CEq/cm2/min; P< 0.05) but not 22Na+ transport, as well as positive Isc value towards the NPE side (7.54 ± 0.58 CA/cm2, P < 0.001) were observed. From baseline, only when applied on NPE (but not on PE) side, cAMP evoked transient Isc peak-increase (20.68 ± 2.79 CA/cm2, P < 0.001) that was followed by long-lasting Isc plateau-increase (7.43 ± 1.21 CA/cm2, P < 0.001). The Isc increase was associated with a PD change that became more negative towards the NPE side (peak-response, -1.08 ± 0.15 mV, P < 0.001). A transient increase of net PE-to-NPE transepithelial 36Cl- flux increase was observed only during the peak increase (1.03 ± 0.18 CEq/cm2/min). On the PE side cAMP evoked transient 36Cl- fluxes in both PE-to-NPE and NPE-to-PE directions leading to no significant net transepithelial flux. No net transepithelial 22Na+ flux could ever be observed. CONCLUSIONS. On the NPE side of porcine ciliary epithelium, cAMP evokes a transepithelial transport of ions (Isc) that does not involve Na+ but only transiently Cl- from the PE to the NPE side. |
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