Nicotinic acetylcholine receptors (nAChRs) containing the alpha6 subunit have been implicated in neurological and psychiatric conditions including Parkinson’s and nicotinic dependence. Despite their potential therapeutic importance, little is known about the biophysical properties of these receptors in part because of their restricted tissue distribution and poor expression in heterologous systems. Nevertheless, a recent report by Dr. Albillos’ laboratory demonstrated that the alpha6beta4 subtype is the main nAChR expressed in human adrenal chromaffin cells. This seminal report constitutes the only functional demonstration of native human alpha6beta4 nAChRs and represents a timely opportunity to gain valuable insights into its biophysical properties and to further our understanding of this receptors involvement in the stimulus-secretion response of chromaffin cells. This proposal intends to characterize the biophysical properties of native human alpha6beta4 nAChRs, their interaction with mitochondria via calcium, and their functional regulation by reactive oxygen species (ROS) produced by mitochondria under pathological conditions. The specific aims of this proposal are: 1) to characterize the alpha6-containing nAChR subtype(s) present in human adrenal chromaffin cells and to investigate the regulation of their expression by nicotine; 2) to study the functional interaction between alpha6beta4 nAChRs and mitochondria; 3) the regulation of this nAChR subtype by mitochondrial ROS.