title: [Amplitude of miniature potentials of motor neurons in the frog Rana ridibunda].
abstract: Miniature synaptic potentials have been recorded from motoneurones of the isolated spinal cord of the frog Rana ridibunda. In normal Ringer's solution, their frequency varied from 5 to 50/sec, whereas their amplitude reached 2-5 mV. Only 50-300 microV (rarely 0.5-1.5 mV) potentials persisted when TTX was added to Ringer's solution and/or Ca was replaced by Mn. However, in Ca-free solution, TTX in combination with Mn did not decrease the amplitude of miniature potentials, provided the initial values varied within 50-300 microV. Noise fluctuations did not exceed 40-50 microV, and the ratio of the number of miniature potentials of 50 microV to the number of 50 microV noise potentials was about 10:1. The observed miniature potentials with an amplitude of 50-100 microV coincide with the quantal units calculated by other authors from statistical analysis of the unitary EPSPs evoked by primary afferents or by ventrolateral tract fibers.
mesh_terms: D000818:Animals; D008345:Manganese / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D008839:Microelectrodes; D009046:Motor Neurons / Q000187:drug effects / Q000502:physiology*; D011895:Rana ridibunda; D013116:Spinal Cord / Q000187:drug effects / Q000502:physiology; D013779:Tetrodotoxin / Q000494:pharmacology
chemical_list: D008345:Manganese; D013779:Tetrodotoxin
vernacular_title: Almplituda miniatornykh potentsialov v motoneĭronakh liagushki Rana ridibunda.