Avtor/Urednik		Smrkolj, Tomaž
Naslov		Morfometrična analiza sinaptičnih jedrnih skupkov v posamičnih vlaknih hitre in počasne skeletne mišice
Tip		monografija
Kraj izdaje		Ljubljana
Založnik		Medicinska fakulteta
Leto izdaje		2000
Obseg		str. 34
Jezik		slo
Abstrakt		Introduction and aim: In addition to the differences in gene expression patterns in the synaptic and extrasynaptic regions, the distribution of nuclei is also nonuniform in the mammalian skeletal muscle fiber. Myonuclei are packed at much higher density in the neuromuscular junction (NMJ) region than in the extrajunctional parts of the fiber. Higher concentration of genes in the neuromuscular junction (NMJ) area could theoretically suffice to reach critical concentrations of gene products relevant for maintenance and functioning of the NMJ and might therefore be an additional mechanism contributing to the specialisation of the NMJ part of the fiber. Slow muscle fibers are electromechanically active for longer time periods than fast fibers and the frequency patterns of action potentials are different in both fiber types. This difference might reflect in the distribution of synaptic myonculei and the arrangement of synaptic Schwann cells. In order to elucidate this question we tested the following hypotheses: 1) The number of synaptic myonuclei is significantly higher in slow fibers than in fast fibers. 2) The number of synaptic Schwann celds determined by counting their nuclei is proportional to NMJ area. 3) The reach of the influences of neural trophic factors in the skeletal muscle ftbers does not differ in regard to the fiber type. Methods: Nuclei in single muscle fibers of m. extensor digitorum longus (fast) and m. soleus (slow) were labelled with SYTOX green nuclear acid stain and the endplates with rhodamine-tagged alpha bungarotoxin. The latter undergoes almost irreversible binding to acetylcholine receptors, which are highly concentrated solely in postsynaptic membrane of NMJ. Images obtained by confocal microscopy on Zeiss confocal microscope were further analysed after three-dimensional reconstruction with image analysing computer software Zeiss LSM 510. (Abstract truncated at 2000 characters).
Deskriptorji		MUSCLE, SKELETAL MUSCLE FIBERS, FAST-TWITCH MUSCLE FIBERS, SLOW-TWITCH NEUROMUSCULAR JUNCTION CELL NUCLEUS RATS, WISTAR SCHWANN CELLS HISTOCYTOCHEMISTRY IMAGE PROCESSING, COMPUTER-ASSISTED BUNGAROTOXINS