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Biomedical subjects

N Otake

Publications and source records attributed to N Otake.

At least 109 records · Page 6Linked to original sources
PubMed1978

Studies on the ionophorous antibiotics. XV The monovalent cation selective ionophorous activities of carriomycin, lonomycin and etheromycin.

The cations selectivity profiles of the carboxylic ionophores, carriomycin, lonomycin and etheromycin, have been investigated by measuring the complexation affinities for metal cations and the cation transport activity through an organic barrier. In a two-phase partition study, carriomycin and lonomycin formed complexes more readily with K+ than with NH4+, Rb+ or Na+, but not with Li+ or Cs+. On the other hand, etheromycin exhibited a great preference for K+ or NH4+ over Na+, Li+ or Rb+, but displayed no binding affinity for Cs+. The alklaine degradation product of lonomycin exhibited a preference for K+ or Na+, but its complexation affinities were much lower than those of the parent compound. Carriomycin, lonomycin and etheromycin efficiently transported K+, Rb+ and Na+ through a CCl4 barrier. But did not carry Ca2+. These antibiotics caused a massive release of K+, Rb+ or Na+, but not of Li+ and Cs+, from mitochondria previously loaded with these cations by valinomycin or monazomycin. Thus, it is concluded that carriomycin, lonomycin and etheromycin are monovalent cation selective ionophores.

Animals↗
PubMed1978

Studies on the ionophorous antibiotics. XVI. The ionophore-mediated calcium transport and concomitant osmotic swelling of mitochondria.

The effects of various carboxylic ionophores on divalent metal cation translocation in mitochondria have been investigated. High levels of divalent cation ionophores lysocellin and lasalocid A (10 approximately 50 micrometer) produced mitochondrial osmotic swelling in Ca2+ or Mg2+ medium, which was associated with an increase of cation influx. The extent of swelling was a function of both the ionophore and cation concentrations in the medium. This effect was larger in mitochondria de-energized by treatment with antimycin A and oligomycin than in respiring mitochondria. On the other hand, the monovalent cation ionophores carriomycin and etheromycin at concentrations of 50 approximately 100 micrometer also induced mitochondrial swelling in Ca2+ medium but were ineffective in Mg2+ medium. Addition of ruthenium red reversed divalent cation ionophore-induced swelling and released Ca2+ from preloaded mitochondria. In contrast, ruthenium red increased monovalent cation ionophore-induced swelling. In a divalent cation-free medium, lysocellin and lasalocid A caused depletion of membrane-bound Ca2+ and released endogenous Ca2+ and Mg2+ from mitochondria, while carriomycin and etheromycin exerted only a limited effect. These results indicate that the divalent cation ionophores affect divalent cation distribution in mitochondria by increasing both influx and efflux of the cations through the inner membrane.

Animals↗
PubMed1977

Studies on the ionophorous antibiotics. XI. The artifacts and the degradation products of lysocellin.

Lysocellin is a new polyether antibiotic produced by Streptomyces cacaoi var. asoensis and is characterized as a broad spectrum ionophore having a higher complexation affinity for divalent cations than for monovalents and also having an ability to transport biological amines. The structures of two artifacts designated L1 and M1 have been elucidated based on spectral evidence, and the formation mechanism of these compounds was discussed with respect to the reactivity of the antibiotic. In addition, a number of degradation and modified products were prepared in order to examine their biological activity and to utilize as the model compounds for 13C-NMR assignment.

Acetylation↗
PubMed1977

Studies on the ionophorous antibiotics. XII. Effects of ionophore lysocellin on cation distribution and respiration in mitochondria.

The effects of the ionophore lysocellin on the movements of Ca2+, Mg2+ and alkali metal cations and its effect on energy utilization by rat liver mitochondria have been investigated. At a concentration of 0.05 micrometer, lysocellin induced dissociation of membrane-bound calcium, and an apparent steady state was established across the inner membrane between energy-linked calcium accumulation and the ionophore-induced depletion of calcium. No detectable efflux of intramitochondrial Ca2+ and Mg2+ was induced by 0.05 micrometer lysocellin, but the uptake of exogenously added calcium was significantly inhibited. The ionophore augmented Mg2+ release from mitochondria induced by Ca2+ addition and also caused rapid release of K+ from mitochondria preloaded with K+ by valinomycin or monazomycin. High levels (0.5 approximately 10 micrometer of lysocellin caused massive depletion of endogenous Ca2+, Mg2+ and K+ from mitochondria, resulting in disruption of mitochondrial functions including release of state 4 respiration, stimulation of ATPase and inhibition of ADP- or DNP-stimulated respiration. Structure-activity studies with chemically modified compounds of lysocellin indicated the important role of terminal carboxylic acid and C21 hydroxyl function in the activity of the ionophore, and there is a good correlation between the effect of lysocellin on mitochondrial cation movements and its ability to complex with cations determined in an organic solvent-water two-phase partition system.

Adenosine Triphosphatases↗
PubMed1976

Salinomycin effects on mitochondrial ion translocation and respiration.

The effects of salinomycin on alkali cation transport and membrane functions in rat liver mitochondria have been investigated. After potassium uptake, stimulated by valinomycin or monazomycin in the presence of adenosine 5'-triphosphate, salinomycin caused rapid release of K(+) from mitochondria. Salinomycin reversed valinomycin- or monazomycin-induced oscillatory swelling of mitochondria preloaded with K(+), Rb(+), and Na(+) but was without effect on Li(+) or Cs(+) preloaded mitochondria. Salinomycin blocked the retention of K(+) more effectively than the retention of Rb(+) or Na(+). Salinomycin inhibited both coupled and uncoupled respiration with strict substrate specificity in medium of low but not in high K(+) concentration. The oxidation of glutamate, alpha-ketoglutarate, and malate plus pyruvate was inhibited by salinomycin, but that of beta-hydroxybutyrate or succinate was not significantly affected. Salinomycin inhibited adenosine triphosphatase activity of mitochondria induced by valinomycin or monazomycin in K(+) and Rb(+) medium without significantly affecting adenosine triphosphatase activity in Li(+), Na(+), or Cs(+) medium. Oxidative phosphorylation in mitochondria was inhibited by salinomycin but the inhibitory effect of salinomycin lacked the substrate specificity observed for respiration. It is proposed that salinomycin perturbs mitochondrial functions by acting as a mobile carrier for alkali cations through membranes.

Adenosine Triphosphatases↗
PubMed1976

Deisovalerylblastmycin produced by Streptomyces SP.

A new antifungal antibiotic was isolated from the fermentation broth of Streptomyces sp. 5140-A1. Degradation studies of the crystalline antibiotic, m.p. 186 approximately 188 degrees C, C21H28O8N2, suggested Piricularia oryzae and less toxicity against killfish than antimycin A--blastmycin antibiotics.

Animals↗