Recent studies have linked mutations in TRPC6 (a non-selective cation channel) with progression of renal disease (1,2). These studies showed that the podocyte, within the glomerulus is the target cell for abnormal calcium signalling. Here we demonstrate a difference in calcium channel activity between the two cell types that form the ultrafiltration barrier within the glomerulus (podocytes and glomerular endothelial cells (GEnCs)). This channel activity is dependent on nephrin, a cell adhesion molecule (and podocyte marker) located at the podocyte slit diaphragm. FFA, which has been suggested to activate TRPC6 whilst non-specifically blocking other cation channels (3) was used to stimulate channel activity. Human conditionally immortalised podocytes (hCIPs), nephrin-deficient (ND) hCIPs and hGEnCs were loaded with 10μM Fura2-AM. They were incubated in buffer containing 200nM (low) or 5mM (high) Ca²⁺ and stimulated with 200μM FFA in the presence or absence of 200nM thapsigargin to deplete intracellular calcium ([Ca²⁺]_i ) stores, in varying amounts of FCS. Changes in [Ca²⁺]_i were measured using the normalised fluorescence intensity ratio at excitation wavelengths of 340nm to 380nm (R_norm). FFA increased the R_norm in hCIPs in the presence and absence of a Ca²⁺ concentration gradient (5mM [Ca²⁺]_o 1.44±0.11 fold increase, p<0.01, n=7; 200nM [Ca²⁺]_o; 1.58±0.01 fold increase, p<0.01, n=6 unpaired t-tests), which was significantly reduced when [Ca²⁺]_i stores were depleted (post-thapsigargin 1.08±0.06 fold increase, p<0.05, n=6). However, the presence of FCS post-thapsigargin restored the FFA induced increase in R_norm (1.78±0.15 fold increase, p<0.01, n=6 unpaired t-test). In contrast the response to FFA in hGEnCs post-thapsigargin was not blocked (2.01±0.12 fold increase, p<0.01 paired t-test, n=4). Similarly, in the absence of nephrin (NDhCIPs) the response to FFA was not blocked post-thapsigargin (1.6±0.06 fold increase, p<0.01, n=4, paired t-test). The post-thapsigargin response to FFA was FCS dose dependent. In conclusion in hCIPs the FFA induced increase in [Ca²⁺]_i was dependent on thapsigargin-sensitive [Ca²⁺]_i stores, except in the presence of FCS whereby it became store independent in an FCS dose-dependent manner. [Ca²⁺]_i store-dependent activation by FFA was also nephrin dependent and was not seen in hGEnCs. This evidence suggests novel activity of a not-yet specified calcium channel in hCIPs, which is nephrin and FCS dependent and potentially involved in progression of renal disease.