Neurotransmitter release at the chick cochlear hair cell afferent synapse / Marc Daniel Eisen.

Format:

Book

Manuscript

Microformat

Thesis/Dissertation

Author/Creator:

Eisen, Marc Daniel.

Contributor:

Saunders, James C., advisor.

Parsons, Thomas D., advisor.

University of Pennsylvania.

Language:

English

Subjects (All):

Penn dissertations--Neuroscience.

Neuroscience--Penn dissertations.

Neurosciences.

Academic Dissertations as Topic.

Medical Subjects:

Neurosciences.

Academic Dissertations as Topic.

Local Subjects:

Penn dissertations--Neuroscience.

Neuroscience--Penn dissertations.

Physical Description:

x, 125 pages : illustrations ; 29 cm

Production:

2000.

Summary:

Cochlear hair cells are the linchpins in the auditory pathway that convert sound, comprised of mechanical rarefactions and compressions, into electrical impulses in the auditory nerve. The product of this energy transfer exhibits a remarkable fidelity that allows us to hear and localize a wide amplitude range of sounds with complex spectral composition for an indefinite duration. The goal of this research is to examine the presynaptic mechanisms of neurotransmitter release at the cochlear hair cell afferent synapse that permits prolonged high rates of release. Individual tall hair cells within a semi-intact preparation of the chick basilar papilla were subject to voltage clamp analysis via the whole-cell patch clamp technique. Neurotransmitter release was monitored by measuring increases in membrane capacitance associated with synaptic vesicle fusion. Neurotransmitter release required the influx of calcium through voltage-gated, dihydropyridine-sensitive calcium channels. Different stimulation protocols revealed a finite releasable pool of synaptic vesicles whose combined surface area was as large as approximately 4% of the entire plasma membrane and was released with a time constant of 0.6 seconds during maximum calcium influx. Mobilization of this releasable pool was inhibited by 5 mM intracellular concentrations of the calcium buffers EGTA or BAPTA. Myosin light chain kinase and myosin ATPase were also necessary to recruit the releasable pool. These results suggest that one of the means by which the cochlear hair cell maintains a high rate of neurotransmitter release is to mobilize a cytoplasmic pool of releasable vesicles possibly by using a myosin-based molecular motor.

Notes:

Supervisors: James C. Saunders; Thomas D. Parsons.

Thesis (Ph.D. in Neuroscience) -- University of Pennsylvania, 2000.

Includes bibliographical references.

Local Notes:

University Microfilms order no.: 99-65472.

OCLC:

244971294