Research Description

Certain substances, when bound to the membranes of neurons, cardiac and skeletal muscle, salivary acini, and other cells, behave as molecular indicators of membrane potential. The optical properties of these molecules, most notably fluorescence and absorbance, vary in a linear fashion with potential and may, therefore, be used to monitor action potentials, synaptic potentials, or other changes in membrane voltage from a large number of sites at once, without the necessity of using electrodes. Our laboratory is engaged in the development of more sensitive probes, extending the technology associated with their use, and in using these molecular voltmeters for optical recording of membrane potential from hitherto inaccessible regions of single neurons such as axon and neuroendocrine terminals and axonal and dendritic processes, and from many sites simultaneously, with single cell resolution, in simple mammalian nervous systems, in order to study the spatial and temporal patterning of activity.

Also, we are continuing to exploit the optical properties of potentiometric probes to detect the voltage changes in the nerve terminals of vertebrates, and to correlate alterations in the shape of the nerve terminal action potential with the release of neuropeptides monitored through rapid changes in light scattering. We are also very much interested in the volume changes in nerve terminals, which seem to accompany water movement through ion channels.