Philanthotoxin blocks quisqualate‐, AMPA‐ and kainate‐, but not NMDA‐, induced excitation of rat brainstem neurones in vivo

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Abstract
1 The effect of electrophoretic ejection of philanthotoxin (the polyamine toxin, from the Egyptian digger wasp) was tested on responses of brainstem and spinal neurones in the pentobarbitone-anaesthetized rat to excitatory amino acids. 2 Philanthotoxin caused a dose-dependent reduction of responses to quisqualate, α-amino-3-hydroxy-5-phenyl-4-isoxazolepropionate (AMPA) and kainate with little effect on those to N-methyl-d-aspartate (NMDA). 3 The time-course of this antagonist action was slow. In particular the rate of recovery was dependent on frequency of ejection of the agonist. This agonist-dependent recovery suggests that philanthotoxin has a channel blocking mode of action on mammalian central neurones.