Modulation by Calcium and Chloride of cAMP-Induced Short-Circuit Current Increase in Porcine Ciliary Processes

　　吴仁毅 马宁

　　浙江大学医学院附属第二医院眼科中心 310009

　　Purpose:To investigate how calcium and chloridemodulate short-circuit current(Isc)increase induced by 8-bromo-cAMP(cAMP)in isolated porcine ciliary processes.

　　Method:In an Ussing-type chamber，peak Isc dose-response curves to cAMP were constructed in isolated porcine ciliary processess.The effect of calcium channel blockers or calcium/chloride concentration on the Isc increase was assessed.

　　Results:cAMP increased Isc when applied on NPE side.Isc increase was moderately inhibited by mibefradil，nimodipine，or a 0.5 mM calcium solution，and abolished by a 0 mM calcium solution on the NPE.Isc increase was moderately enhanced by a 5 mM calcium solution or Bay K8644 on the NPE.Isc increase was strongly inhibited by a low chloride solution on PE side.This Inhibition was not significantly affected by 0.5，2.5，or 5 mM calcium solultion(NPE).

　　Conclusions:cAMP-induced Isc increase appears to involve an extracellular influx of calcium on the NPE side and the presence of chloride on the PE side in pig ciliary processes.Furthermore，the absence of chloride and calcium on the PE and NPE side，respectively，appears to be limiting factors in this process.