Inhibitory miniature synaptic potentials in rat motoneurons.
In the newborn rat spinal cord, spontaneous potentials were recorded, with KCl electrodes, from motoneurons in the presence of tetrodotoxin (10(-6) g ml-1) to abolish nerve impulses. These potentials occurred at low frequencies (less than 2 Hz), and their mean amplitude was a fraction of 1 mV. An increase of osmolarity with sucrose or an increase of extracellular K+, increased the frequency of miniature synaptic potentials. The amplitude of the spontaneous potentials was increased by intracellular injection of Cl-. Strychnine (2-25 microM) completely abolished the spontaneous potentials. It is suggested that these potentials are produced by the spontaneous release of packages of inhibitory transmitter at synapses on motoneurons.
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002712:Chlorides / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D009045:Motor Endplate / Q000502:physiology; D009046:Motor Neurons / Q000502:physiology*; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013331:Strychnine / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology
D002712:Chlorides; D013779:Tetrodotoxin; D013331:Strychnine; D011188:Potassium