Biomaterial Database

Apical K+ channels in frog skin (Rana temporaria): cation adsorption and voltage influence gating kinetics. 1981

W Zeiske, and W Van Driessche

Open-close kinetics of fluctuating K+ channels in the apical frog skin membrane were studied with noise analysis of the K+ current (IK). The mucosa to serosa directed IK was obtained with serosal NaCl- and mucosal KCl-Ringer under voltage clamp conditions. Mucosal protons (pH greater than 4), several polyvalent metal ions, and choline shifted the plateaus (SO) of the Lorentzian component in the IK noise spectrum to higher, but the corner frequency (fc) to lower values. SO was lowered at pH less than 4, due to a K+-channel block by H+. Ca2+, Sr2+, H+ (pH greater than 4) and choline did not affect IK. A slight reduction of IK was seen with Mg2+, Mn2+, Co2+, Ni2+, Zn2+, Cu2+ and La3+. At pH greater than 4, the H+-induced shifts in SO an fc were almost abolished in solutions of high mucosal Ca2+ concentrations. Clamping the transepithelial potential difference to more positive values (with respect to the serosa) shifted the Lorentzian parameters SO and fc in the same way as the cations did. As with protons, mucosal Ca2+ interferred with the effect of voltage. The interference of cationic (probably fixed charge screening) and voltage effects suggests a common, more general mechanism of action, namely alterations in K+-channel fluctuation kinetics by changes in local electrical fields. On this basis, the rates for the open-close reaction of K+ channels and their mean lifetime were calculated. We found that e.g. increasing [Ca2+]O from 1-10 mM caused no change of the mean open time, but increased the mean time "closed" of the K+ channel by a factor of about 1.5. Other mucosal cations, as well as depolarizing clamp potentials are thought to have the same effect.

UI	MeSH Term	Description	Entries
D007473	Ion Channels	Gated, ion-selective glycoproteins that traverse membranes. The stimulus for ION CHANNEL GATING can be due to a variety of stimuli such as LIGANDS, a TRANSMEMBRANE POTENTIAL DIFFERENCE, mechanical deformation or through INTRACELLULAR SIGNALING PEPTIDES AND PROTEINS.	Membrane Channels,Ion Channel,Ionic Channel,Ionic Channels,Membrane Channel,Channel, Ion,Channel, Ionic,Channel, Membrane,Channels, Ion,Channels, Ionic,Channels, Membrane
D008564	Membrane Potentials	The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).	Resting Potentials,Transmembrane Potentials,Delta Psi,Resting Membrane Potential,Transmembrane Electrical Potential Difference,Transmembrane Potential Difference,Difference, Transmembrane Potential,Differences, Transmembrane Potential,Membrane Potential,Membrane Potential, Resting,Membrane Potentials, Resting,Potential Difference, Transmembrane,Potential Differences, Transmembrane,Potential, Membrane,Potential, Resting,Potential, Transmembrane,Potentials, Membrane,Potentials, Resting,Potentials, Transmembrane,Resting Membrane Potentials,Resting Potential,Transmembrane Potential,Transmembrane Potential Differences
D011188	Potassium	An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.
D011522	Protons	Stable elementary particles having the smallest known positive charge, found in the nuclei of all elements. The proton mass is less than that of a neutron. A proton is the nucleus of the light hydrogen atom, i.e., the hydrogen ion.	Hydrogen Ions,Hydrogen Ion,Ion, Hydrogen,Ions, Hydrogen,Proton
D011896	Rana temporaria	A species of the family Ranidae occurring in a wide variety of habitats from within the Arctic Circle to South Africa, Australia, etc.	European Common Frog,Frog, Common European,Common European Frog,Common Frog, European,European Frog, Common,Frog, European Common
D002412	Cations	Positively charged atoms, radicals or groups of atoms which travel to the cathode or negative pole during electrolysis.	Cation
D004553	Electric Conductivity	The ability of a substrate to allow the passage of ELECTRONS.	Electrical Conductivity,Conductivity, Electric,Conductivity, Electrical
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D012879	Skin Physiological Phenomena	The functions of the skin in the human and animal body. It includes the pigmentation of the skin.	Skin Physiological Processes,Skin Physiology,Physiology, Skin,Skin Physiological Concepts,Skin Physiological Phenomenon,Skin Physiological Process,Concept, Skin Physiological,Concepts, Skin Physiological,Phenomena, Skin Physiological,Phenomenas, Skin Physiological,Phenomenon, Skin Physiological,Phenomenons, Skin Physiological,Physiological Concept, Skin,Physiological Concepts, Skin,Physiological Phenomena, Skin,Physiological Phenomenas, Skin,Physiological Phenomenon, Skin,Physiological Phenomenons, Skin,Process, Skin Physiological,Processes, Skin Physiological,Skin Physiological Concept,Skin Physiological Phenomenas,Skin Physiological Phenomenons