Patch-clamp is still the gold standard for direct recording of ionic currents through channel proteins. Conventional patch clamp is extremely sensitive and provides a wealth of detailed information, but has limited throughput and is labour intensive. Automated planar patch clamp devices show considerable promise, being easier to operate with higher throughput. Protocols have been developed for cell lines, but we were interested in the potential benefits for studies of endogenous channels of primary cells. Using two planar systems, Patchliner Quattro and Port-a-Patch (Nanion Technologies GmbH), we routinely obtained GΩ seals and high-quality whole-cell patch clamp recordings from human saphenous vein (HSV) smooth muscle cells and rabbit synoviocytes. These cells have previously proved quite difficult to patch-clamp by conventional methodology. In this study we used sphingosine-1-phosphate (S1P) a major endogenous signalling phospholipid which plays an important role in the cardiovascular system (Levade et al. 2001). We also used gadolinium (Gd³⁺), which is a commonly used blocker of non-selective cation channels, but in the micromolar range stimulates TRPC5 channels (Xu et al. 2006). Currents were elicited by voltage ramps from -100 mV to +100 mV for 1 s every 10 s from a holding potential of 0 mV or -60 mV for smooth muscle cells and synoviocytes, respectively. Cell membrane capacitance for the HSV cells was 56.2 ± 4.1 pF and access resistance was 5.9 ± 0.4 MΩ (n = 48). Application of Gd³⁺ (100 μM) caused a significant inhibition of the endogenous basal currents (36 ± 0.6 % decrease, n = 7, P<0.01). However, in the presence of S1P (10 μM), Gd³⁺ produced a significant activation of endogenous current (73 ± 4.5% increase, n = 9, P<0.01). Success in producing Patchliner recordings from HSV cells, maintained for 12-15 min, was surprisingly greater than for conventional patch-clamp methodology (56.2%, n = 128 vs <10% n = 403). Success was also greater for synoviocytes (38.2%, n = 189 vs 500). These results suggest that there is potential for planar patch-clamp devices in the study of ionic currents through endogenous channel proteins of primary cells.