The variation in action of excitatory amino acids in relation to distance of iontophoretic application to spinal motoneurones

• Published in: Acta physiologica Scandinavica 1985-07, Vol.124 (3), p.421-427
• Main Authors: FLATMAN, J. A., LAMBERT, J. D. C., ENGBERG, I.
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Cats; Central nervous system; Central neurotransmission. Neuromudulation. Pathways and receptors; excitatory amino acids; Female; Fundamental and applied biological sciences. Psychology; Glutamates - pharmacology; Glutamic Acid; Homocysteine - analogs & derivatives; Homocysteine - pharmacology; Iontophoresis; Male; Membrane Potentials - drug effects; Microelectrodes; Neurons - drug effects; Receptors, Amino Acid; Receptors, Cell Surface - drug effects; somal and dendritic application; Spinal Cord - drug effects; spinal motoneurones; Vertebrates: nervous system and sense organs
• ISSN: 0001-6772; 1365-201X
• DOI: 10.1111/j.1748-1716.1985.tb07678.x

Intracellular recordings were made from lumbosacral motoneurones of barbiturate‐anaesthetized cats. dl‐Homocysteate (DLH) and l‐glutamate were iontophoresed extracellularly over a range of distances from the impaled motoneurone. Movement of the iontophoretic electrode unit was controlled by a micromanipulator which was advanced independently of that moving the intracellular electrode. Depolarizations to DLH were first detected at a greater distance from the impaled motoneurones (mean, 383 μm) than depolarizations to l‐glutamate (mean, 165 μm). As the point of application approached the soma of the motoneurone, depolarizations developed more rapidly, were larger and the latent period of the l‐glutamate depolarization became shorter. Dendritic ‘hot‐spots’ of the depolarizing action of l‐glutamate were not detected.