Contributions of Astrocyte and Neuronal Volume to CA1 Neuron Excitability Changes in Elevated Extracellular Potassium.

Rapid increases in cell volume reduce the size of the extracellular space (ECS) and are associated with elevated brain tissue excitability. We recently demonstrated that astrocytes, but not neurons, rapidly swell in elevated extracellular potassium ([K] ) up to 26 mM. However, effects of acute astrocyte volume fluctuations on neuronal excitability in [K] have been difficult to evaluate due to direct effects on neuronal membrane potential and generation of action potentials.

Honey, I shrunk the extracellular space: Measurements and mechanisms of astrocyte swelling.

Astrocyte volume fluctuation is a physiological phenomenon tied closely to the activation of neural circuits. Identification of underlying mechanisms has been challenging due in part to use of a wide range of experimental approaches that vary between research groups. Here, we first review the many methods that have been used to measure astrocyte volume changes directly or indirectly.

Astrocyte-Selective Volume Increase in Elevated Extracellular Potassium Conditions Is Mediated by the Na/K ATPase and Occurs Independently of Aquaporin 4.

Astrocytes and neurons have been shown to swell across a variety of different conditions, including increases in extracellular potassium concentration (^[K]). The mechanisms involved in the coupling of K influx to water movement into cells leading to cell swelling are not well understood and remain controversial. Here, we set out to determine the effects of ^[K] on rapid volume responses of hippocampal CA1 pyramidal neurons and stratum radiatum astrocytes using real-time confocal volume imaging.

Inducible Colonic M Cells Are Dependent on TNFR2 but Not Ltβr, Identifying Distinct Signalling Requirements for Constitutive Versus Inducible M Cells.

Background And Aims: M cells associated with organised lymphoid tissues such as intestinal Peyer's patches provide surveillance of the intestinal lumen. Inflammation or infection in the colon can induce an M cell population associated with lymphoid infiltrates; paradoxically, induction is dependent on the inflammatory cytokine tumour necrosis factor [TNF]-α. Anti-TNFα blockade is an important therapeutic in inflammatory bowel disease, so understanding the effects of TNFα signalling is important in refining therapeutics.

Differential Potency of 2,6-Dimethylcyclohexanol Isomers for Positive Modulation of GABAA Receptor Currents.

GABAA receptors meet all of the pharmacological requirements necessary to be considered important targets for the action of general anesthetic agents in the mammalian brain. In the following patch-clamp study, the relative modulatory effects of 2,6-dimethylcyclohexanol diastereomers were investigated on human GABAA (α1β3γ2s) receptor currents stably expressed in human embryonic kidney cells. Cis,cis-, trans,trans-, and cis,trans-isomers were isolated from commercially available 2,6-dimethylcyclohexanol and were tested for positive modulation of submaximal GABA responses.