http://www.physiologicinstruments.com Physiologic Instruments designs and manufactures instrumentation, Ussing Chamber Systems and Data Acquisition products for studying transport across epithelial barriers. Transepithelial voltage, short-circuit current and resistance are measured using single and multi-channel voltage/current clamps that may be directly connected to Acquire & Analyze for automating data collection and analysis. http://www.physiologicinstruments.com