Pharmacological characteristics of jonotropic glutamate receptor subtypes in cultured rat retinal ganglion cells

• Published in: Japanese Journal of Pharmacology 2000, Vol.82 (suppl.1), p.142-142
• Main Authors: Satoshi Mukai, Keisuke Shoge, Makoto Shinya, Hiromu K. Mishima, Kumatoshi Ishihara, Masashi Sasa
• Format: Article
• Language: Japanese
• ISSN: 0021-5198

We have previously succeeded in cultureing high quality rat retinal ganglion cells (RGC) using a separation method with a magnetic cell sorter (MACS) and found the existence of jonotropic glutamate receptor subtypes. The present study was performed to examine pharmacological properties of ionotropic glutamate receptor subtypes in cultured RGC using a whole-cell patch clamp method. MACS-separated primary RGC cultures were obtained from 4- to 5-day-old Wistar rats. At post-culture 1 week, whole-cell currents induced by N-metyl-D-aspartate (NMDA), kainate (KA) and α-amino-3-hydroxy-5-metyl-4-isoxazole propionic acid (AMPA) using a U-tube system were recorded under voltage-clamp conditions at a holding potential of -60 mV. Brief application (2 sec) of NMDA (3-300 μM), KA (1-1000 μM) or AMPA (0.3-3000 μM) induced inward currents in a dose-dependent manner. The maximum currents induced by NMDA (300 μM), KA (1 mM) and AMPA (3 mM) were 224.3±64.6 (EC_50 32.4 μM, n=10), 1001.3±191.6 (EC_50 43.9 μM, n=-5) and 823.7±265.1 pA (EC_50 46.5 μM, n=7), respectively. The current-voltage relationships of NMDA (300 μM), KA (100 μM) and AMPA (100 μM) were almost liniar in the presense of glycine and absence of Mg^2+ . NMDA (300 μM)-induced inward currents were suppressed more negetive than -20 mV by the addition of Mg^2+ (1.1 mM). MACS rendered expression of NMDA, KA and AMPA receptors possible and confirmed thease receptor to display electrophysiological properties similar to those of mammalian brain neurons.