title: [Characteristics of the functional properties of the spinal cord motoneurons of old rats].
abstract: The mean membrane potential (MP) of old rats did not differ significantly from that in young mature rats ((58.4 +/- +/-1,4 mV and 56.6 +/- 1.26 mV, respectively). At the same time the frequency of detection of motor neurons with the MP OF 70 mV and more fell by 18.6%, and with the MP of 50-59 mV -increased by 14.2% in the old, in comparison with the young animals. The direct excitability threshold in old rats decreased (3.0 +/- 3-10(-9) in young mature and 2.0 +/- 0.2-10(-9) a in old rats; P  less than 0.02). The number of discharges per 50 msec of the neuron poliarization reached 4-5, constituting 80-100 pulse/min. When determined by the first two intervals the action potential frequency reached 125 pulse/sec, and in the young mature rats--over 300 pulse/sec. The duration of antidromic spikes was increased (1.02 +/- 0.09 msec in young mature animals and 1.65 +/- 0.14 msec in the old animals; P less than 0.001). The antidromic spikes of the neurons in old mature rats, as a rule, had no delayed depolarization.
mesh_terms: D000367:Age Factors; D000375:Aging; D000818:Animals; D004558:Electric Stimulation; D008564:Membrane Potentials; D009046:Motor Neurons / Q000502:physiology*; D009431:Neural Conduction; D051381:Rats; D013116:Spinal Cord / Q000502:physiology*
vernacular_title: K kharakteristike funktsional'nykh svoĭstv motoneĭronov spinnogo mozga starykh krys