antimycin and methylglucoside

Metabolic and permeability properties of enterocytes isolated by treatment of rat small intestine with hyaluronidase or EDTA were compared. No significant difference was observed in the ability of the two types of cell to produce lactate from glucose. However, while cells obtained with hyaluronidase accumulate alpha-methylglucoside, cells obtained with EDTA were unable to accumulate the sugar above the medium concentrations. When resuspended in a medium designed to resemble the intracellular medium, potentiometric measurements showed that cells obtained with hyaluronidase released Ca2+ to the medium while cells obtained with EDTA accumulated it. Using 45Ca transport assays, this was shown to be an ATP-dependent process, the accumulated 45Ca being totally released by the addition of the ionophore A23187. When cells obtained with EDTA were resuspended in a medium containing concentrations of free Ca2+ higher that 10 microM, the uptake was partially inhibited by sodium orthovanadate and also by oligomycin and antimycin. At free Ca2+ concentrations lower than 1 microM, the accumulation was inhibited up to 87% by sodium orthovanadate while mitochondrial inhibitors inhibited only 5%. Thus, it appears that during their preparation cells obtained with hyaluronidase retain their integrity while cells obtained with EDTA become permeable to Ca2+ and other ions. The usefulness of both types of preparation in metabolic and transport studies is discussed.

Topics: Animals; Antimycin A; Calcimycin; Calcium; Calcium-Transporting ATPases; Carbonyl Cyanide m-Chlorophenyl Hydrazone; Cell Membrane Permeability; Edetic Acid; Glycolysis; Hyaluronoglucosaminidase; Intestinal Absorption; Intestine, Small; Methylglucosides; Nigericin; Oligomycins; Rats; Vanadates; Vanadium

Marquis, Robert E. (University of Rochester, Rochester, N.Y.). Nature of the bactericidal action of antimycin A for Bacillus megaterium. J. Bacteriol. 89:1453-1459. 1965.-Antimycin A, a fungicidal antibiotic which specifically inhibits metabolic reduction of cytochrome c, was found to be lethal for Bacillus megaterium. However, the bactericidal action was correlated with a capacity of antimycin to hinder plasma-membrane functions other than cytochrome-mediated respiration. With conditions under which oxygen consumption was not appreciably depressed, antimycin almost completely inhibited concentrative uptake of both alpha-aminoisobutyrate and alpha-methylglucoside, and also caused death of cells. When present in amounts greater than those required for killing or for inhibition of nutrilite uptake, antimycin also induced extensive loss of inorganic phosphate and other substances from whole cells, inhibited aerobic respiration, and acted as a lytic agent for isolated protoplasts. The lytic potency of antimycin was greater, on a molar basis, than that of digitonin, hexachlorophene, polymyxin B, and all but one of a number of test detergents. Protoplasts concentrated antimycin primarily in or on the plasma membrane, and the refractive index of isolated protoplast membranes rose sharply as a result of antimycin binding. In all, antimycin-induced lysis appeared not to include dissolution of the protoplast membrane similar to that produced by dodecyl sulfate. Rather, the lytic process seemed more akin to that induced by cationic detergents or by polymyxin.

Topics: Aminoisobutyric Acids; Anti-Bacterial Agents; Antifungal Agents; Antimycin A; Bacillus megaterium; Bacteriolysis; Butyrates; Cell Membrane; Cell Membrane Permeability; Cytochromes; Glycosides; Manometry; Metabolism; Methylglucosides; Pharmacology; Phosphates; Polymyxin B; Polymyxins; Protoplasts; Research; Spectrophotometry; Surface-Active Agents