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The inwardly rectifying potassium channel Kir4.1 has been suggested to underlie the principal K(+) conductance of mammalian Müller cells and to participate in the generation of field potentials and regulation of extracellular K(+) in the retina. To further assess the role of Kir4.1 in the retina, we generated a mouse line with targeted disruption of the(More)
To understand the cellular and in vivo functions of specific K(+) channels in glia, we have studied mice with a null mutation in the weakly inwardly rectifying K(+) channel subunit Kir4.1. Kir4.1-/- mice display marked motor impairment, and the cellular basis is hypomyelination in the spinal cord, accompanied by severe spongiform vacuolation, axonal(More)
Guanine nucleotide-binding proteins (G proteins) activate K+ conductances in cardiac atrial cells to slow heart rate and in neurons to decrease excitability. cDNAs encoding three isoforms of a G-protein-coupled, inwardly rectifying K+ channel (GIRK) have recently been cloned from cardiac (GIRK1/Kir 3.1) and brain cDNA libraries (GIRK2/Kir 3.2 and GIRK3/Kir(More)
Knock-in mice were generated that harbored a leucine-to-serine mutation in the alpha4 nicotinic receptor near the gate in the channel pore. Mice with intact expression of this hypersensitive receptor display dominant neonatal lethality. These mice have a severe deficit of dopaminergic neurons in the substantia nigra, possibly because the hypersensitive(More)
A subset of ganglion cells in the mammalian retina express the photopigment melanopsin and are intrinsically photosensitive (ipRGCs). These cells are implicated in non-image-forming visual responses to environmental light, such as the pupillary light reflex, seasonal adaptations in physiology, photic inhibition of nocturnal melatonin release, and modulation(More)
G protein-gated inward rectifier K+ (GIRK) channels mediate hyperpolarizing postsynaptic potentials in the nervous system and in the heart during activation of Galpha(i/o)-coupled receptors. In neurons and cardiac atrial cells the time course for receptor-mediated GIRK current deactivation is 20-40 times faster than that observed in heterologous systems(More)
Stria vascularis of the cochlea generates the endocochlear potential and secretes K(+). K(+) is the main charge carrier and the endocochlear potential the main driving force for the sensory transduction that leads to hearing. Stria vascularis consists of two barriers, marginal cells that secrete potassium and basal cells that are coupled via gap junctions(More)
In the neurological mutant mouse weaver, granule cell precursors proliferate normally in the external germinal layer of the cerebellar cortex, but fail to differentiate. Granule neurons purified from weaver cerebella have greatly reduced G protein-activated inwardly rectifying K+ currents; instead, they display a constitutive Na+ conductance. Expression of(More)
Melanopsin (Opn4) is a photopigment found in a subset of retinal ganglion cells (RGCs) that project to various brain areas. These neurons are intrinsically photosensitive (ipRGCs) and are implicated in nonimage-forming responses to environmental light such as the pupillary light reflex and circadian entrainment. Recent evidence indicates that ipRGCs respond(More)