Direct Patch Recording From Identified Presynaptic Terminals Mediating Glutamatergic EPSCs in the Rat CNS, in Vitro

J Physiol. 1994 Sep 15;479 ( Pt 3)(Pt 3):381-7. doi: 10.1113/jphysiol.1994.sp020303.

Abstract

1. An in vitro brainstem slice preparation of the superior olivary complex has been developed permitting patch recording from a presynaptic terminal (calyx of Held) and from its postsynaptic target--the principal neurone of the medial nucleus of the trapezoid body (MNTB). 2. The fluorescent stain DiI (1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate) was used in fixed tissue and Lucifer Yellow in living slices, to identify calices enclosing single MNTB neuronal somata. 3. Whole-cell recording from the MNTB neurone shows evoked EPSCs preceded by a prespike, corresponding to the presynaptic action potential (AP). In some cases one patch pipette recorded from both pre- and postsynaptic elements, but confirmation of exclusively presynaptic recording was obtained using pipettes containing Lucifer Yellow in a further eleven cases. 4. Under current clamp, the pre- and postsynaptic sites could be distinguished by their response to step depolarizations; presynaptic terminals generated a train of APs at frequencies up to 200 Hz, while MNTB neurones gave a single AP. Each presynaptic AP had an after-hyperpolarization lasting less than 2 ms. 5. Under voltage clamp, step depolarizations of presynaptic terminals generated a tetrodotoxin-sensitive inward current followed by rapidly activating outward potassium currents at potentials more positive than -60 mV. The outward current exhibited little inactivation over the 150 ms steps and 4-aminopyridine (200 microM) blocked 63.0 +/- 14.5% (mean +/- S.D., n = 3) of the sustained current at 0 mV. Like the squid giant synapse, mammalian terminals express rapidly activating 'delayed rectifier'-type potassium currents.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials / drug effects
  • Action Potentials / physiology
  • Animals
  • Brain / cytology
  • Brain / drug effects
  • Brain / physiology*
  • Carbocyanines
  • Electrophysiology
  • Fluorescent Dyes
  • Glutamic Acid / metabolism
  • Glutamic Acid / physiology*
  • Isoquinolines
  • Microscopy, Confocal
  • Neurons / physiology
  • Patch-Clamp Techniques
  • Pons / cytology
  • Pons / metabolism
  • Presynaptic Terminals / drug effects
  • Presynaptic Terminals / physiology*
  • Rats
  • Receptors, AMPA / metabolism
  • Receptors, N-Methyl-D-Aspartate / metabolism
  • Tetrodotoxin / pharmacology

Substances

  • Carbocyanines
  • Fluorescent Dyes
  • Isoquinolines
  • Receptors, AMPA
  • Receptors, N-Methyl-D-Aspartate
  • Glutamic Acid
  • 3,3'-dioctadecylindocarbocyanine
  • Tetrodotoxin
  • lucifer yellow