Biomaterial Database

Individual synaptic vesicles mediate stimulated exocytosis from cochlear inner hair cells. 2018

Chad Paul Grabner, and Tobias Moser

Synaptic Nanophysiology Group, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany; chadgrabner@gmail.com.

Spontaneous excitatory postsynaptic currents (sEPSCs) measured from the first synapse in the mammalian auditory pathway reach a large mean amplitude with a high level of variance (CV between 0.3 and 1). This has led some to propose that each inner hair cell (IHC) ribbon-type active zone (AZ), on average, releases ∼6 synaptic vesicles (SVs) per sEPSC in a coordinated manner. If true, then the predicted change in membrane capacitance (Cm) for such multivesicular fusion events would equate to ∼300 attofarads (aF). Here, we performed cell-attached Cm measurements to directly examine the size of fusion events at the basolateral membrane of IHCs where the AZs are located. The frequency of events depended on the membrane potential and the expression of Cav1.3, the principal Ca2+-channel type of IHCs. Fusion events averaged 40 aF, which equates to a normal-sized SV with an estimated diameter of 37 nm. The calculated SV volumes showed a high degree of variance (CV > 0.6). These results indicate that SVs fused individually with the plasma membrane during spontaneous and evoked release and SV volume may contribute more variability in EPSC amplitude than previously assumed.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D008564	Membrane Potentials	The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).	Resting Potentials,Transmembrane Potentials,Delta Psi,Resting Membrane Potential,Transmembrane Electrical Potential Difference,Transmembrane Potential Difference,Difference, Transmembrane Potential,Differences, Transmembrane Potential,Membrane Potential,Membrane Potential, Resting,Membrane Potentials, Resting,Potential Difference, Transmembrane,Potential Differences, Transmembrane,Potential, Membrane,Potential, Resting,Potential, Transmembrane,Potentials, Membrane,Potentials, Resting,Potentials, Transmembrane,Resting Membrane Potentials,Resting Potential,Transmembrane Potential,Transmembrane Potential Differences
D008810	Mice, Inbred C57BL	One of the first INBRED MOUSE STRAINS to be sequenced. This strain is commonly used as genetic background for transgenic mouse models. Refractory to many tumors, this strain is also preferred model for studying role of genetic variations in development of diseases.	Mice, C57BL,Mouse, C57BL,Mouse, Inbred C57BL,C57BL Mice,C57BL Mice, Inbred,C57BL Mouse,C57BL Mouse, Inbred,Inbred C57BL Mice,Inbred C57BL Mouse
D002118	Calcium	A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D002462	Cell Membrane	The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.	Plasma Membrane,Cytoplasmic Membrane,Cell Membranes,Cytoplasmic Membranes,Membrane, Cell,Membrane, Cytoplasmic,Membrane, Plasma,Membranes, Cell,Membranes, Cytoplasmic,Membranes, Plasma,Plasma Membranes
D003599	Cytoskeleton	The network of filaments, tubules, and interconnecting filamentous bridges which give shape, structure, and organization to the cytoplasm.	Cytoplasmic Filaments,Cytoskeletal Filaments,Microtrabecular Lattice,Cytoplasmic Filament,Cytoskeletal Filament,Cytoskeletons,Filament, Cytoplasmic,Filament, Cytoskeletal,Filaments, Cytoplasmic,Filaments, Cytoskeletal,Lattice, Microtrabecular,Lattices, Microtrabecular,Microtrabecular Lattices
D005089	Exocytosis	Cellular release of material within membrane-limited vesicles by fusion of the vesicles with the CELL MEMBRANE.
D005260	Female		Females
D006199	Hair Cells, Auditory, Inner	Auditory sensory cells of organ of Corti, usually placed in one row medially to the core of spongy bone (the modiolus). Inner hair cells are in fewer numbers than the OUTER AUDITORY HAIR CELLS, and their STEREOCILIA are approximately twice as thick as those of the outer hair cells.	Auditory Hair Cell, Inner,Auditory Hair Cells, Inner,Cochlear Inner Hair Cell,Cochlear Inner Hair Cells,Hair Cell, Auditory, Inner,Inner Auditory Hair Cell,Inner Auditory Hair Cells,Inner Hair Cells,Cell, Inner Hair,Cells, Inner Hair,Hair Cell, Inner,Hair Cells, Inner,Inner Hair Cell
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