Compared to RGCs, only low levels of K2P channel expression were detected within other retinal neurones, including photoreceptors, horizontal cells, bipolar cells and amacrine cells. This pattern of expression is potentially in keeping the nature of electrical activity observed within the retina. With the exception of RGCs (and a few specialised subtypes of bipolar cells82 and amacrine cells8384), the majority of retinal cell types do not classically encode light signals as patterns of action potential firing but instead show graded changes in membrane potential28586. It is therefore possible that these cell types show less functional reliance on K+ leak currents than typical spike firing neurones, such as RGCs. Our data do however indicate the expression of at least four distinct K2P channels within Müller cells, including TWIK-1, TASK-3, TRAAK, and TREK-2. A previous study has reported the presence of a pH sensitive background leak K+ current in Müller cells of mice (and also rat and guinea pig)87, and expression of multiple K2P channels have been reported in Müller cells of the amphibian retina (Rana pipiens) where they have been shown to perform roles in cell volume regulation and responses to retinal ischemia8788. Based on our data it is possible that TWIK-1, TASK-3, TRAAK and TREK-2 may perform similar roles in Müller cells of the mammalian retina, and that TASK-3 may be responsible for the pH sensitive current previously described.