To understand the role of different K(+) channel subtypes in glial cell-mediated spatial buffering of extracellular K(+), immunohistochemical localization of inwardly rectifying K(+) channel subunits (Kir2.1, Kir2.2, Kir2.3, Kir4.1, and Kir5.1) was performed in the retina of the mouse. Stainings were found for the weakly inward-rectifying K(+) channel subunit Kir4.1 and for the strongly inward-...

Inward-rectifier potassium (Kir) channels differ from the canonical K(+) channel structure in that they possess a long extended pore (approximately 85 A) for ion conduction that reaches deeply into the cytoplasm. This unique structural feature is presumably involved in regulating functional properties specific to Kir channels, such as conductance, rectification block, and ligand-dependent gatin...

We previously reported an enhanced tonic dilator impact of ATP-sensitive K+ channels in afferent arterioles of rats with streptozotocin (STZ)-induced diabetes. The present study explored the hypothesis that other types of K+ channel also contribute to afferent arteriolar dilation in STZ rats. The in vitro blood-perfused juxtamedullary nephron technique was utilized to quantify afferent arteriol...

Inward rectifying potassium (Kir) channels participate in regulating potassium concentration (K(+)) in the central nervous system (CNS), including in the retina. We explored the contribution of Kir channels to retinal function by delivering Kir antibodies (Kir-Abs) into the rat eye in vivo to interrupt channel activity. Kir-Abs were coupled to a peptide carrier to reach intracellular epitopes. ...

bstract —Rapid changes in extracellular K concentration [K ]o) in the mammalian CNS are counteracted by simple assive diffusion as well as by cellular mechanisms of K learance. Buffering of [K ]o can occur via glial or neuronal ptake of K ions through transporters or K -selective chanels. The best studied mechanism for [K ]o buffering in the rain is called K spatial buffering, wherein the glial...

Structure-function analyses of K+ channels identify a common pore architecture whose gating depends on diverse signal sensing elements. The "gatekeepers" of the long, ATP-inhibited KIR6.0 pores of KATP channels are ABC proteins, SURs, receptors for channel opening and closing drugs. Several competing models for SUR/KIR coupling exist. We show that SUR TMD0, the N-terminal bundle of five transme...

The amino-terminal and carboxyl-terminal domains of inwardly rectifying potassium (Kir) channel subunits are both intracellular. There is increasing evidence that both of these domains are required for the regulation of Kir channels by agents such as G-proteins and nucleotides. Kir6.2 is the pore-forming subunit of the ATP-sensitive K(+) (K(ATP)) channel. Using an in vitro protein-protein inter...

Numerous studies demonstrated that membrane cholesterol is a major regulator of ion channel function. The goal of this review is to discuss significant advances that have been recently achieved in elucidating the mechanisms responsible for cholesterol regulation of ion channels. The first major insight that comes from growing number of studies that based on the sterol specificity of cholesterol...

In this review, we present the basic properties, physiological functions, regulation, and pathological alterations of four major classes of K+ channels that have been detected in vascular smooth muscle cells. Voltage-dependent K+ (Kv) channels open upon depolarization of the plasma membrane in vascular smooth muscle cells. The subsequent efflux of K+ through the channels induces repolarization ...

Inward-rectifier potassium channels (Kir channels) stabilize the resting membrane potential and set a threshold for excitation in many types of cell. This function arises from voltage-dependent rectification of these channels due to blockage by intracellular polyamines. In all Kir channels studied to date, the voltage-dependence of rectification is either strong or weak. Here we show that in ca...