This programme introduces the frog skin, as a model to study membrane transport. Analogies with renal epithelial transport are discussed. The parameters measured are voltages and ionic currents across the membrane with the current-clamp/ Voltage-clamp techniques. Hands on practice on this macroscopic model form the basis for theoretical considerations of ion-channel behaviour, carrier mediated transport kinetics and patch-clamp techniques. The participants also learn principles of designing physiological salt solutions and techniques to isolate and measure current through a single transport system across membranes.