Calcium plays a crucial role in coupling excitation to many functions of neurons. One important example is the activation of ion channel gating. A recently discovered class of Ca++.activated channels is the non.specific cation (CAN) channel. Dr. Partridge intends to establish that these channels, found in a wide diversity of tissues, constitute a unique channel class. Dr. Partridge has shown previously that CAN channels exist in burster neurons. Although the characteristics of CAN channels can be surmised from piecemeal data from numerous tissues, a solid understanding of their role in cell function and a detailed study of channel characteristics in a single preparation are lacking. The proposed research will utilize cell.attached and excised membrane patches from burster neurons to measure CAN channel selectivity, kinetics, and links to cell metabolism. The project will accomplish two important goals. (1) The physiological role of CAN currents has been established in burster neurons, thus a detailed description of CAN channels will provide an important link between the cellular phenomenon of bursting and the action of a specific class of membrane channels; and (2) Focusing descriptive information about CAN channels on one preparation will provide strong evidence to support the hypothesis that CAN channels represent a unique class of membrane.