The role of K+ channels in bile acid-independent bile flow (BAIF) was studied in the isolated and bile duct-cannulated perfused rat liver by changing the driving force on K+and by using a variety of K+channel blockers. Bile flow rate, effluent perfusate K+ content, and portal pressure were measured. Increase in perfusate K+ from 5.9 to 80 mM caused inhibition of bile flow that could be fitted t...

Potassium ion current in nerve membrane, I(K), has traditionally been described by I(K) = g(K)(V - E(K)), where g(K) is the K ion conductance, V is membrane potential and E(K) is the K(+) Nernst potential. This description has been unchallenged by most investigators in neuroscience since its introduction almost 60 years ago. The problem with the I(K) approximately (V - E(K)) proportionality is ...

The complexity of mammalian physiology requires a diverse array of ion channel proteins. This diversity extends even to a single family of channels. For example, the family of Ca2+-activated K channels contains three structural subfamilies characterized by small, intermediate, and large single channel conductances. Many cells and tissues, including neurons, vascular smooth muscle, endothelial c...

There are many reports for involvement of ATP-sensitive potassium channels in pancreatic, cardiac and vascular smooth muscle cells. This study examined the effect of single doses of K+ channel openers diazoxide, minoxidil and K+ channel blockers chlorpropamide, glibenclamide on serum concentration of aldosterone in male rats. Blood samples were obtained 60 minutes after drug treatment and serum...

We studied the mechanism by which Hanatoxin (HaTx) inhibits the drk1 voltage-gated K+ channel. HaTx inhibits the K+ channel by shifting channel opening to more depolarized voltages. Channels opened by strong depolarization in the presence of HaTx deactivate much faster upon repolarization, indicating that toxin bound channels can open. Thus, HaTx inhibits the drk1 K+ channel, not by physically ...

Zinc is a substance that regulates neural excitability by binding whit sodium channel and potassium channel. The efficiency of free zinc ion, make down the neural survival rate, reduced the peak amplitude of Na+ and make depolarization Na channel, increased the peak amplitude of transition outward k+ currents and delayed rectifier. Also it is an effective blocker of one subtype of tetrodoxine (...

The effects of a novel vasorelaxant agent, MCC-134 (1-[4-(1H-imidazol-1-yl)benzoyl]-N-methyl-cyclobutanecarbothioamide++ +), were examined on reconstituted ATP-sensitive K(+) (K(ATP)) channels, which are composed of an inwardly rectifying K(+) channel, Kir6.2, and three types of sulfonylurea receptors (SUR): SUR1, SUR2A, and SUR2B. Each type of K(ATP) channel was heterologously expressed in hum...

Voltage-gated n-type K(V) and Ca(2+)-activated K+ [K(Ca)] channels were studied in cell-attached patches of activated human T lymphocytes. The single-channel conductance of the K(V) channel near the resting membrane potential (Vm) was 10 pS with low K+ solution in the pipette, and 33 pS with high K+ solution in the pipette. With high K+ pipette solution, the channel showed inward rectification ...

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 were 9.2 times larger in cells with e...

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