EFFECTS OF SACCHARIDIC DERIVATIVES ON P-TYPE VOLTAGE-DEPENDENT CALCIUM CHANNELS EXPRESSED IN XENOPUS OOCYTES

We have studied the effects of two saccharidic derivatives [MAGlu-O-C- 8 and (MAGlu)(2)-O-C-8] on P-type voltage-dependent calcium channels e xpressed in Xenopus oocytes following injection of rat cerebellar mRNA . At a concentration of 100 mu M, MAGlu-O-C-8 inhibited 52 +/- 8% (n = 12) of the barium current whereas (MAGlu)(2)-O-C-8 inhibited 71 +/- 7 % (n = 11) of the same current. Moreover, on the Ca2+-dependent chlori de current (I-CI(Ca)), MAGlu-O-C-8 showed a half maximal effect at a c oncentration of 98 +/- 5 mu M (n = 17) and (MAGlu)(2)-O-C-8 at 33 +/- 5 mu M (n = 16). It is concluded that the two saccharidic derivatives may constitute a novel class of calcium channel antagonists with speci ficity to the central nervous system channels, namely the P-type calci um channels.