Shepelev S. Synaptic transmission in skeletal muscles оn conditions of experimental vitamin B1 deficiency

Object: neuromuscular junctions in mammalian striated muscle. The purpose: estimation of the state of the neuromuscular transmission in striated skeletal muscles at vitamin В1 (thiamin) deficiency in an organism. Methods: modelling of thiamine deficiency at experimental animals, study of the spontaneous and evoked transmitter secretion of the mice diaphragmatic nerve terminals using standard microelectrode technics, a tensometric method of registration of the mice diaphragmatic muscle contractile reactions, fluorimetric method of determination of the common thiamin content in a biological material. Results: it was shown that in isolated phrenico-hemidiaphragmatic preparations obtained from animals gettings a thiamine-defficient diet, the amplitude of miniature end-plate potentials (mEPPs) and end-plate potentials (EPPs) on the 10th, 15th and 20th days and the quantal content of EPPs on the 20th day of feeding became significantly smaller than in preparations obtained from animals of control and pair-feed groups. In preparations obtained 3 and 24 hours but not 72 hours after subcutaneous injections of 400 mg/kg oxythiamine, the amplitude of EPPs and their quantal content were significantly smaller than in the control. In preparations obtained from animals intraperitoneally injected with 100 mg/kg pyrithiamine 1.5 hours earlier, the amplitudes of mEPPs and EPPs, as well as quantal content of EPP, were significantly smaller than in the control. The frequency of mEPPs, membrane potential of muscle fibers and the post-synaptic chemosensitivity to carbachol, the nicotinic acetylcholine receptors agonist, under influence of alimentary thiamine deficiency and vitamin B1 antagonists remained unchanged. Vitamin B1 deficiency in the organism provokes the decreasing of neuromuscular transmission safety, what can lead to motor functions disturbances. Application field: physiology, biochemistry, pharmacology.