Neurotransmitters and neurohormones are released from a neuron or endocrine cell primarily through the process of exocytosis. Central to this process is the calcium-dependent fusion of a small, membrane-limited vesicle with the outer membrane of the cell. Two immediate consequences of this fusion are the release of the vesicle contents (transmitter or hormone) into the extra- cellular space and an increase in the surface area of the cell. This project will provide basic information about the mechanism of transmitter release by exploiting recent technical advances to measure these minute changes in cell surface area. Using the adrenal chromaffin cell as a model system and triggering release by brief changes in the electrical potential across the cell membrane, this project will provide new information about the quantitative relationship between calcium and transmitter release.
