The Same Synaptic Vesicles Originate Synchronous and Asynchronous Transmitter Release.
Transmitter release and synaptic vesicle exo- and endocytosis during high-frequency stimulation (20 pulses/s) in the extracellular presence of different bivalent cations (Ca(2+), Sr2+ or Ba2+) were studied in frog cutaneous pectoris nerve-muscle preparations. It was shown in electrophysiological experiments that almost only synchronous transmitter release was registered in a Ca(2+)-containing solution; a high intensity of both synchronous and asynchronous transmitter release was registered in a Sr2+-containing solution, and asynchronous transmitter release almost only was observed in a Ba2+-containing solution. It was shown in experiments with a FM 1-43 fluorescent dye that the synaptic vesicles that undergo exocytosis-endocytosis during synchronous transmitter release (Ca-solutions) are able to participate in asynchronous exocytosis in Ba-solutions. The vesicles that had participated in the asynchronous transmitter release (Ba-solutions) could subsequently participate in a synchronous release (Ca-solutions). It was shown in experiments with isolated staining of recycling and reserve synaptic vesicle pools that both types of evoked transmitter release originate from the same synaptic vesicle pool.
Kazan State Medical University, Ministry of Health of the Russian Federation, Butlerov Str., 49, Kazan, 420012, Russia.
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Grigoryev
Kazan State Medical University, Ministry of Health of the Russian Federation, Butlerov Str., 49, Kazan, 420012, Russia.
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Zefirov
Ca2+, Sr2+, Ba2+ ions; evoked synchronous and asynchronous transmitter release; motor nerve ending; synaptic vesicle exocytosis and endocytosis; synaptic vesicle pools