Heterocellular electrical coupling between cells of the arterial wall enables conducted dilatation. It is not established whether endothelial cell Ca2+ signals contribute to this response at the upstream sites. We used double- or triple-cannulated rat cremaster arteries to study local and conducted dilatation and endothelial cell Ca2+ events. Arteries were pressurized to 70 mmHg, and the endothelial cells luminally loaded with the Ca2+-indicator Oregon Green 488 BAPTA-1. Arteries developed myogenic tone, and dilated to luminal perfusion of ACh, ATP, and the activator of KATP channels, levcromakalim (LVK). Each agonist evoked both local and conducted dilatation, near maximally dilating arteries 1000 µm upstream from the region of agonist luminal perfusion. In all cases, the local dilatation was associated with increases in endothelial cell Ca2+. Levcromakalim increased the frequency of spontaneous endothelial cell Ca2+ events, without evoking the cell-wide Ca2+ waves observed with ACh and ATP. This increase in activity was also observed when extracellular K+ was raised to 10 mM, suggesting that hyperpolarization per se has an effect to increase spontaneous activity in the endothelium. The Ca2+ events occur within discrete regions of the endothelial cells that appear to align with endothelial cell projections to smooth muscle. Increases in Ca2+ events were also observed upstream from the site of agonist delivery, and we suggest are secondary to hyperpolarization at these distal sites. These data suggest that the processes associated with conducted dilatation include a component of increased endothelial cell Ca2+ signalling in discrete domains within these cells.