Neuropharmacology and Neurotoxicology: PDF OnlyFocal blockade of single unit synaptic transmission by iontophoresis of antagonistsKirkwood, Peter A.1,; Schmid, Kurt2; Otto, Markus2; Sears, Thomas A.1Author Information 1Sobell Department of Neurophysiology, Institute of Neurology, Queen Square, London WC1N 3BG, UK 2Physiologisches Institut, II. Lehrstuhl, Johannes Gutenberg-Universität Mainz, Saarstr. 21, D-6500 Mainz, Germany NeuroReport: April 1991 - Volume 2 - Issue 4 - p 185-188 Buy Abstract WE have assessed the use of iontophoresis for investigating the pharmacology of synaptic transmission from individual presynaptic neurones in-vivo, by modifying extracellular focal synaptic potentials (FSPs) recorded by spike-triggered averaging. FSPs from two types of excitatory neurone (muscle spindle primary afferents and expiratory bulbospinal neurones) and from one inhibitory interneurone were studied in the thoracic ventral horn of anaesthetized cats. The antagonist of excitatory amino acids at non-NMDA receptors, DNQX, blocked the FSPs from the first two, as did bicuculline for the third. Thus the FSPs were generated by excitatory amino acids acting via non-NMDA receptors and GABA, respectively. The postsynaptic neurones were probably motoneurones. Merits and limitations of the method are discussed. © Lippincott-Raven Publishers.