Electrophysiological Analysis of the Functional State of Spinal Cord Motoneurons in Rats with Parathyroprivous Tetany

摘要

A comparative analysis of baseline activity, tetanic and post-tetanic increases and decreases in the frequencies of spinal cord motoneuron responses to high-frequency (50 and 100 Hz) stimulation (HFrS) of the fl exor (G) and extensor (P) nerves of the hindlimb was performed in normal rats and rats with parathyroprivous (hypocalcemic) tetany. Experiments were run using on-line selection and programmed analysis of spike activity. Signifi cant shifts in tetanic and post-tetanic motoneuron activity were recorded on days 3–7 and 21–22 of the development of acute and chronic tetanization respectively, without any signifi cant change in baseline activity. Along with sharp increases in post-stimulus excitatory changes in activity in response to HFrS during the development of acute tetany, there was relative weakening in animals with chronic tetany. At the same time, there was weakening or complete disappearance of depressor reactions during the period of development of acute tetany with some degree of stabilization in animals with latent tetany. A cause-effect relationship was identifi ed between motor disorders in parathyroid insuffi ciency on the one hand and impairments to the ratio of inhibitory/excitatory processes in spinal cord motoneurons on the other.