Induced active transport of ions in mitochondria.

Pressman, Berton C.

doi:10.1073/pnas.53.5.1076

Cited by 301 publications

(77 citation statements)

References 14 publications

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“…A translocação de íons e o rompimento de gradientes iônicos são responsáveis pelos efeitos terapêuticos e tóxicos dos ionóforos (Pressman 1965, Pressman 1968. No primeiro caso, a ação dos ionóforos sobre a membrana celular de bactérias ruminais, coccídios ou fungos patogênicos, resulta em efeitos benéficos para o animal hospedeiro (Pressman 1976, Russel & Strobel 1989.…”

Section: Mecanismo De Açãounclassified

Intoxicação por antibióticos ionóforos em animais

2009

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RESUMO.-O uso terapêutico de antibióticos ionóforos em medicina veterinária difundiu-se muito nos últimos anos, com conseqüente aumento no risco de intoxicação em animais. Antibióticos ionóforos são usados como coccidiostáticos e como aditivo em alimentos para animais, com o propósito de estimular o desenvolvimento e o ganho de peso. Os ionóforos mais utilizados na alimentação de animais são a monensina, lasalocida, nasarina e salinomicina. Há uma grande variação na susceptibilidade dos efeitos tóxicos dos ionóforos de acordo com a espécie animal. A intoxicação pode ocorrer quando dosagens elevadas de ionóforos são adicionadas aos alimentos, ou quando ionóforos são incluídos inadvertidamente ou acidentalmente em dosagens não corretas para determinada espécie animal. Casos de intoxicação têm sido descritos em bovinos, ovinos, suínos, eqüinos, cães e aves. Para os eqüi-nos os ionóforos são extremamente tóxicos. São considerados seguros quando usados nas espécies-alvo, dentro das dosagens recomendadas pelo fabricante. The therapeutic use of ionophores in veterinary medicine has grown in the last years, with resultant increase in the risk of poisoning in animals. Ionophores are used as food additives as coccidiostacts in several animal species and growth promoter and bloat prevention in ruminants. The most often used ionophores are monensin, lasalocid, narasin and salinomycin. There is a great variation in the susceptibility to the toxic effect of ionophores in different animal species. Poisoning can occur when the dosage is too high or when not correct doses for a certain animal species are given. Cases of poisoning have been described in sheep, swine, horses, dogs and poultry. For horses ionophores are extremely toxic. The use of ionophores is only safe when used accordingly to the instructions of the manufacturer and especially for each animal species. In this paper the most important data regarding clinical-pathological and pathogenic aspects, and also the conditions in which the poisoning may occur are critically reviewed.

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Section: Mecanismo De Açãounclassified

Intoxicação por antibióticos ionóforos em animais

2009

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“…The induction of K ÷ uptake by nonactin [11] or by valinomycin [12], expected to abolish the membrane potential without disturbing the pH gradient across the inner membrane, stimulates the uptake of pyruvate by the mitochondria (Table II) One would expect only minor effects of ionophores on pyruvate adsorption. This expectation is realized if a-cyano-3-hydroxycinnamate is applied as inhibitor, but not with a-cyanocinnamate.…”

Section: Incubation Mediummentioning

confidence: 99%

Accumulation of pyruvate by isolated rat liver mitochondria

Vaartjes

Geelen

Bergh

1979

Biochimica et Biophysica Acta (BBA) - Bioenergetics

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“…The general make-up of this doughnut would be similar to the structure of the ionophorous antibiotic, valinomycin (30).…”

Section: Mechanism Of Cytolysis By Complement 2957mentioning

confidence: 99%

Mechanism of Cytolysis by Complement

Mayer

1972

Proc. Natl. Acad. Sci. U.S.A.

204

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The attack of complement is directed against the lipid moiety of the cell membrane; a single lesion at the site of fixation of complement proteins C5-C9 is responsible for lysis of a cell. There are two hypothetical models for the generation of this membrane lesion. The first of these, designated the leaky-patch model, postulates either direct enzymatic attack or enzymatic generation of a lytic substance by C5-C9. As a result, the phospholipid bilayer of the membrane would be disrupted and a leaky patch permitting passage of water and salt would appear. However, this hole would persist only as long as enzymatic action continues. Thus, the leakypatch model would not produce a stable hole, and for this reason it is considered an unlikely mechanism.The second hypothesis, termed the doughnut model, describes a structural concept for creating a hydrophilic passage through the hydrophobic phospholipid bilayer of the membrane. In essence, this would be a rigid and hollow structure, like a doughnut, with a hydrophobic exterior, which is inserted into the phospholipid bilayer of the cell membrane in such a way that its hollow hydrophilic core becomes a channel through which salt and water can exchange freely between the interior of the cell and the extracellular environment. The late-acting complement proteins C5-C9 are the most probable source of the structural components of the doughnut. A combination of the leaky-patch and doughnut models may represent the most likely mechanism.Recent studies of complement (C) have focused attention on the late-acting components, C5-C9, which make up the cytolytic part of the system (1-8). It has been shown that the C4, 2, 3 enzyme activates C5 by cleavage (2, 3) and that the resulting C5b fragment combines with C6, which serves as a stabilizer (4). In turn, the C5b, 6 complex combines with C7 (5, 6) yielding C5b, 6, 7, which appears to be the foundation of the lytic attack mechanism (1). After uptake of C8 by this complex, partial membrane damage is produced as evidenced by slow lysis of erythrocytes in the state erythrocyte-antibody-complement components 1-8 (EAC1-8) on incubation at 370 (7). When the terminal complement component, C9, joins the attack system, rapid lysis ensues indicating overt membrane damage. Recent studies of the reaction of EAC1-8 with C9 (8) have reaffirmed the one-hit theory in its strict sense, namely, that a single membrane Abbreviations: C, C1, C2, C3, etc.-C refers to complement, and the numbers indicate the components of the complement system. The letters "a" or "b", as in C5b, refer to fragments. 935-938. lesion at the C5-C9 locus suffices for lysis, and this has led to an examination of possible mechanisms for producing this lesion. These are described in the present paper in relation to newer concepts of membrane structure.The fluid mosaic model of membrane structure Physicochemical studies of the proteins and lipids in cell membranes have led to a new concept of membrane structure, termed the fluid mosaic model (9, 10). As in the DavsonDa...

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Induced active transport of ions in mitochondria.

Cited by 301 publications

References 14 publications

Intoxicação por antibióticos ionóforos em animais

Intoxicação por antibióticos ionóforos em animais

Accumulation of pyruvate by isolated rat liver mitochondria

Mechanism of Cytolysis by Complement

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