Biomaterial Database

The relationship of pinocytosis and synaptic vesicles at the frog neuromuscular junction. 1984

C K Meshul, and G D Pappas

The fate of the extracellular marker horseradish peroxidase (HRP), following intense transmitter release was studied using identified muscle fibers from the frog sartorius nerve-muscle preparation. The muscle was stimulated indirectly via its nerve at 10 Hz or K+-depolarized for 15 min. Other preparations were also stimulated or K+-depolarized for 15 min and then rested for an additional 15 min. Endings from only identified muscle fibers were photographed with the electron microscope. It was found that in the paradigms studied above, less than 10% of the mean number of synaptic vesicle profiles per section contained the marker. Following electrical stimulation, there was a statistically significant decrease in the mean number of synaptic vesicle profiles per section. After a 15 min rest period, the vesicle profile number had returned to the control value. At this time point, the endplate potential was but 25% of the control. K+-depolarization caused no significant change in the mean number of synaptic vesicle profiles per section. Experiments were also performed to rule out any direct effect of the label on the number of coated and synaptic vesicle profiles. The mean number of labeled coated vesicle profiles increased during either electrical stimulation or K+-depolarization, and then fell during the subsequent rest period. Their numbers accounted for less than 2% of the total number vesicles/section. A suprisingly high number of coated vesicle profiles (as high as 41%) contained no label. This finding is inconsistent with the exclusive role of coated vesicles associated with synaptic vesicle membrane recycling. The low level of HRP labeling of synaptic vesicles is also inconsistent with synaptic vesicles undergoing exo- and endocytosis along the presynaptic plasma membrane.

UI	MeSH Term	Description	Entries
D008854	Microscopy, Electron	Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.	Electron Microscopy
D009469	Neuromuscular Junction	The synapse between a neuron and a muscle.	Myoneural Junction,Nerve-Muscle Preparation,Junction, Myoneural,Junction, Neuromuscular,Junctions, Myoneural,Junctions, Neuromuscular,Myoneural Junctions,Nerve Muscle Preparation,Nerve-Muscle Preparations,Neuromuscular Junctions,Preparation, Nerve-Muscle,Preparations, Nerve-Muscle
D010873	Pinocytosis	The engulfing of liquids by cells by a process of invagination and closure of the cell membrane to form fluid-filled vacuoles.	Pinocytoses
D011189	Potassium Chloride	A white crystal or crystalline powder used in BUFFERS; FERTILIZERS; and EXPLOSIVES. It can be used to replenish ELECTROLYTES and restore WATER-ELECTROLYTE BALANCE in treating HYPOKALEMIA.	Slow-K,Chloride, Potassium
D011894	Rana pipiens	A highly variable species of the family Ranidae in Canada, the United States and Central America. It is the most widely used Anuran in biomedical research.	Frog, Leopard,Leopard Frog,Lithobates pipiens,Frogs, Leopard,Leopard Frogs
D004558	Electric Stimulation	Use of electric potential or currents to elicit biological responses.	Stimulation, Electric,Electrical Stimulation,Electric Stimulations,Electrical Stimulations,Stimulation, Electrical,Stimulations, Electric,Stimulations, Electrical
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D013572	Synaptic Vesicles	Membrane-bound compartments which contain transmitter molecules. Synaptic vesicles are concentrated at presynaptic terminals. They actively sequester transmitter molecules from the cytoplasm. In at least some synapses, transmitter release occurs by fusion of these vesicles with the presynaptic membrane, followed by exocytosis of their contents.	Synaptic Vesicle,Vesicle, Synaptic,Vesicles, Synaptic
D066298	In Vitro Techniques	Methods to study reactions or processes taking place in an artificial environment outside the living organism.	In Vitro Test,In Vitro Testing,In Vitro Tests,In Vitro as Topic,In Vitro,In Vitro Technique,In Vitro Testings,Technique, In Vitro,Techniques, In Vitro,Test, In Vitro,Testing, In Vitro,Testings, In Vitro,Tests, In Vitro,Vitro Testing, In