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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)
Blood flow in the brain is regulated by neurons and astrocytes. Knowledge of how these cells control blood flow is crucial for understanding how neural computation is powered, for interpreting functional imaging scans of brains, and for developing treatments for neurological disorders. It is now recognized that neurotransmitter-mediated signalling has a key(More)
  • E A Newman
  • 2001
Intercellular Ca(2+) waves are believed to propagate through networks of glial cells in culture in one of two ways: by diffusion of IP(3) between cells through gap junctions or by release of ATP, which functions as an extracellular messenger. Experiments were conducted to determine the mechanism of Ca(2+) wave propagation between glial cells in an intact(More)
Efflux of K+ from dissociated salamander Müller cells was measured with ion-selective microelectrodes. When the distal end of an isolated cell was exposed to high concentrations of extracellular K+, efflux occurred primarily from the endfoot, a cell process previously shown to contain most of the K+ conductance of the cell membrane. Computer simulations of(More)
Neuronal activity evokes localized changes in blood flow. Although this response, termed neurovascular coupling, is widely used to monitor human brain function and diagnose pathology, the cellular mechanisms that mediate the response remain unclear. We investigated the contribution of glial cells to neurovascular coupling in the acutely isolated mammalian(More)
  • E A Newman
  • 1993
The voltage- and K(+)-dependent properties of Müller cell currents and channels were characterized in freshly dissociated salamander Müller cells. In whole-cell voltage-clamp experiments, cells with endfeet intact and cells missing endfeet both displayed strong inward rectification. The rectification was similar in shape in both groups of cells but currents(More)
Neuronal activity evokes localized changes in blood flow, a response termed neurovascular coupling. One widely recognized hypothesis of neurovascular coupling holds that glial cell depolarization evoked by neuronal activity leads to the release of K+ onto blood vessels (K+ siphoning) and to vessel relaxation. We now present two direct tests of this glial(More)
Calcium signals were recorded from glial cells in acutely isolated rat retina to determine whether Ca2+ waves occur in glial cells of intact central nervous system tissue. Chemical (adenosine triphosphate), electrical, and mechanical stimulation of astrocytes initiated increases in the intracellular concentration of Ca2+ that propagated at approximately 23(More)
  • E A Newman
  • 1987
The distribution of K+ conductance across the surface of retinal Müller cells was determined in 5 mammalian species--rabbit, guinea pig, mouse, owl monkey, and cat--and in tiger salamander. Potassium conductance was measured by monitoring cell depolarizations evoked by focal ejections of a high-K+ solution onto the surface of freshly dissociated cells. This(More)