HCN1 channels significantly shape retinal photoresponses

Hyperpolarization-activated and cyclic nucleotide-gated (HCN) channels are encoded by four genes (HCN1-4) and are widely expressed in the central and peripheral nervous system and in cardiac tissues. All types of HCN channels are also expressed in the retina. Due to their rapid activation, HCN1 channels, which are expressed most abundantly in the inner segments of the photoreceptors, are particularly well suited to modulate retinal responses to flashed light or background light. In vivo functional analysis of HCN1 knockout mice using electroretinography has shown that HCN1 channels shorten retinal light responses under scotopic conditions and thus play an important role for the responsiveness to high-frequency repetitive stimuli. This chapter summarizes the functional phenotype of HCN1 knockout mice