Aim To study modulation of NMDA recep-tors on inward rectifying potassium channels through investigation of retinal horizontal cells. Methods Whole cell recording was conducted on isolated retinal horizontal cells for observation of inward-rectifying po-tassium currents before and after application of NMDA. Modulation of inward-rectifying currents by NMDA re-ceptor was also tested under calcium-free and chelation of intracellular calcium condition. Results Reduction of inward rectifying potassium currents was induced by activation of NMDA receptors. The effect was attenua-ted when calcium was removed. Conclusion Inhibi-tion of inward rectifying potassium channels can be in-duced by activation of NMDA receptors via intracellular calcium signals.%目的：探讨视网膜水平细胞上激活NMDA受体对其内向整流钾通道的调控作用。方法采用酶解分离的视网膜水平细胞进行膜片钳全细胞记录，在给药激活NMDA受体前后，分别记录内向整流钾通道的电流大小；另外在无钙及螯合胞内钙条件下，观察NMDA受体对内向整流钾通道的作用。结果激活NMDA受体后，内向整流钾通道电流减小，灌流洗脱后电流恢复；在无钙和螯合胞内钙的条件下，激活NMDA受体不能改变内向整流钾通道活动。结论激活视网膜水平细胞NMDA受体可以通过胞内钙信号抑制内向整流钾通道电流。
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