Biomaterial Database

Alamethicin channel permeation by Ca2+, Mn2+ and Ni2+ in bovine chromaffin cells. 1991

R I Fonteríz, and M G López, and J García-Sancho, and A G García

Departamento de Fisiología y Bioquímica, Facultad de Medicina, Universidad de Valladolid, Spain.

Alamethicin causes a concentration-dependent increase of [Ca2+]i in suspensions of bovine adrenal chromaffin cells loaded with fura-2. The basal levels of Cai2+ (234 +/- 37 nM; n = 4) increased to a maximum of 2347 +/- 791 nM (n = 3) with 100 micrograms/ml alamethicin. In the presence of 1 mM Cae2+ the increase reached a plateau within about 2-5 s. This increase was due to Ca2+ entry into chromaffin cells, since in the absence of Cae2+ alamethicin did not modify [Ca2+]i. This contrasts with ionomycin (1 microM) which produced a Cai2+ transient even in the absence of Cae2+. Mn2+ ions also entered chromaffin cells in the presence of alamethicin, as measured by the quenching of fura-2 fluorescence following excitation at 360 nm. Resting chromaffin cells had a measurable permeability to Mn2+ which was drastically increased by cell depolarization by K+ (50 mM) addition. This suggests that Mn2+ is able to permeate voltage-dependent Ca2+ channels. Ni2+ uptake into either resting or K(+)-stimulated chromaffin cells was undetectable, but addition of alamethicin induced rapid uptake of this cation. The alamethicin-induced entry of Ni2+ was decreased by 50 mM K+. Overall, the results are compatible with the formation by alamethicin of ion channels in chromaffin cell plasma membranes.

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
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008345	Manganese	A trace element with atomic symbol Mn, atomic number 25, and atomic weight 54.94. It is concentrated in cell mitochondria, mostly in the pituitary gland, liver, pancreas, kidney, and bone, influences the synthesis of mucopolysaccharides, stimulates hepatic synthesis of cholesterol and fatty acids, and is a cofactor in many enzymes, including arginase and alkaline phosphatase in the liver. (From AMA Drug Evaluations Annual 1992, p2035)
D009532	Nickel	A trace element with the atomic symbol Ni, atomic number 28, and atomic weight 58.69. It is a cofactor of the enzyme UREASE.
D002118	Calcium	A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D002413	Cations, Divalent	Positively charged atoms, radicals or groups of atoms with a valence of plus 2, which travel to the cathode or negative pole during electrolysis.	Divalent Cations
D002417	Cattle	Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.	Beef Cow,Bos grunniens,Bos indicus,Bos indicus Cattle,Bos taurus,Cow,Cow, Domestic,Dairy Cow,Holstein Cow,Indicine Cattle,Taurine Cattle,Taurus Cattle,Yak,Zebu,Beef Cows,Bos indicus Cattles,Cattle, Bos indicus,Cattle, Indicine,Cattle, Taurine,Cattle, Taurus,Cattles, Bos indicus,Cattles, Indicine,Cattles, Taurine,Cattles, Taurus,Cow, Beef,Cow, Dairy,Cow, Holstein,Cows,Dairy Cows,Domestic Cow,Domestic Cows,Indicine Cattles,Taurine Cattles,Taurus Cattles,Yaks,Zebus
D002837	Chromaffin Granules	Organelles in CHROMAFFIN CELLS located in the adrenal glands and various other organs. These granules are the site of the synthesis, storage, metabolism, and secretion of EPINEPHRINE and NOREPINEPHRINE.	Chromaffin Granule,Granule, Chromaffin
D005454	Fluorescence Polarization	Measurement of the polarization of fluorescent light from solutions or microscopic specimens. It is used to provide information concerning molecular size, shape, and conformation, molecular anisotropy, electronic energy transfer, molecular interaction, including dye and coenzyme binding, and the antigen-antibody reaction.	Anisotropy, Fluorescence,Fluorescence Anisotropy,Polarization, Fluorescence,Anisotropies, Fluorescence,Fluorescence Anisotropies,Fluorescence Polarizations,Polarizations, Fluorescence
D000408	Alamethicin	A cyclic nonadecapeptide antibiotic that can act as an ionophore and is produced by strains of Trichoderma viride. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)