Upgrade of patch clamp data acquisition system

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The hepatocyte, the major epithelial cell of the liver, is characterized by a tremendous capacity to maintain its volume in the face of the many functions it is responsible for.  Nutrient absorption, macromolecular synthesis and catabolism, xenobiotic metabolism and excretion and bile formation, all demand that compensatory actions be taken in order to maintain cell volume and intracellular homeostasis.  For instance, cell swelling in response to nutrient uptake is countered by increased efflux of potassium, anion and water.  This Regulatory Volume Decrease (RVD) involves activation of a potassium channel, resulting in the passage of potassium down its concentration to the outside of the cell.  Concomitantly, anion efflux increases, mediated by chloride channels and/or organic anion transporters, and water follows as a consequence of the developing osmotic gradient.  Loss of volume regulatory ability is a common feature of both apoptotic and necrotic death pathways and as such occurs in many liver diseases.  Although we have learned quite a lot about the molecular events underlying potassium and anion efflux over the past few years, we still do not know how these activities are initiated in the liver.  Recently we have demonstrated the molecular and functional expression of cation non-selective Transient Receptor Potential (TRP) channels in isolated hepatocytes and a hepatoma cell line.  We propose that these channels open in response to membrane stretch consequent to cell swelling, and conduct calcium into the cell to stimulate potassium and/or anion efflux pathways.  The equipment applied for in this proposal will allow us to continue our studies into the molecular identification, electrophysiological characterization and physiological roles of the non-selective cation, potassium and chloride channels expressed in resting and osmotically stressed liver cells.  Importantly, this will allow me to continue training students in my laboratory on this technically demanding, stat-of-the-art approach to understanding the molecular processes underlying cell volume regulation and its dysregulation during programmed (apoptosis) and non-programmed (e.g., necrosis of ischemia-reperfusion) cell death.