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At least 19 recordsLinked to original sources

PubMed1977

Role of tissue hypermetabolism in stimulation of ventilation by dinitrophenol.

Several authors have hypothesized that tissue hypermetabolism accounts for increases in ventilation (VE) elicited by 2,4-dinitrophenol. However, some data in the literature indicate that stimulation of VE by isomers of dinitrophenol is unrelated to tissue metabolic rate. To test this latter concept, we compared three different isomers of dinitrophenol (i.e., 2,4-dinitrophenol (2,4-DNP), 2,5-dinitrophenol (2,5,-DNP), 2,6-dinitrophenol (2,6-DNP) with respect to stimulation of VE and with respect to stimulation of oxygen consumption (VO2). In all experiments, 3-4 mg/kg of one dinitrophenol isomer was administered to chloralose anesthetized dogs by intra-arterial infusion. 2,4-DNP elicited large increments in both VE and VO2, 2,6-DNP elicited moderate increments in both VE and VO2, whereas 2,5-DNP elicited small increments in both VE and VO2. These observations demonstrate a correlation between ventilatory and metabolic changes affected by isomers of dinitrophenol. Accordingly, these results are consistent with the hypothesis that ventilatory stimulation by congeners of dinitrophenol is related to tissue hypermetabolism.

Animals↗

PubMed1978

The hyperpolarizing and depolarizing effects of 2,4-dinitrophenol on Ehrlich cells.

The ability of glucose to reverse the effects of dinitrophenol on amino acid uptake in Ehrlich cells is a function of pH. At pH 6.0, the presence of glucose does not reverse the inhibitory action of the uncoupler. Nearly complete restoration occurs with glucose at pH 7.4. At pH 8, the presence of glucose may cause a modest increase in amino acid uptake in presence of dinitrophenol. At all pH values, glucose restores ATP and cellular K+ to the control levels at the same pH. Although the cytoplasmic pH changes with changes in the external pH, the cell interior is more alkaline than the medium near pH 6.0 and more acid than the medium at pH 7.8 even after 45 min incubation at 37 degrees C. With dinitrophenol and in presence of glucose the difference in pH between the medium and the cell is minimal at both pH 6.0 and 7.8.

Adenosine Triphosphate↗

PubMed1975

The effect of 2, 4-dinitrophenol on the growth of Bordetella pertussis in chick tracheal organ culture.

Among various metabolic inhibitors tested, only 2, 4-dinitrophenol inhibited the growth of Bordetella pertussis in chick tracheal organ culture at concentrations nontoxic both for bacterial organisms and for ciliary motility of the tracheal fragments. Although this effect of 2, 4-dinitrophenol was reversible in its early stage, longer treatment with this inhibitor resulted in an irreversible inhibition of bacterial growth due to secondary damage of the tracheal fragments. From these observations, it was postulated that the energy required for bacterial growth might be derived from cellular metabolism sensitive to inhibition with 2, 4-dinitrophenol.

Animals↗

PubMed1975

Inhibition by 2,4-dinitrophenol of 9,10-dimethyl-1,2-benzanthracene carcinogenesis in the hamster cheek pouch.

After topical treatment of cheek pouches of 10 hamsters with 9,10-dimethyl-1,2-benzanthracene and 2,4-dinitrophenol for 10 weeks no carcinomas developed in any of the animals. After treatment of 10 animals with the carcinogen only, there were 49 carcinomas in the 8 survivors. Inhibition of chemical carcinogenesis by dinitrophenol was tentatively attributed to suppression of ATP synthesis and to activation of ATPase by dinitrophenol.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1978

Biochemical changes in the rat brain associated with dinitrophenol-induced brain edema.

The present paper was designed to the study of cerebral edema induced by intracarotid infusion of dinitrophenol. The determinations included variations in three lysosomal enzymes (acid phosphatase, cathepsin C and beta-glucuronidase), Na+-K+-ATP-ase, changes in cerebral RNA and protein concentrations and the synthesis of these macromolecules in vitro. In experimental brain edema a drastic drop in the activity of lysosomal enzymes took place. The acid phosphatase decreased to less than 30% of controls. Cathepsin C and beta-glucuronidase were reduced about 30% and 50% of control levels respectively. Protein concentration in the cerebral tissue also decreased by more than 50%. The concentration of RNA, RNA synthesis, and the level of Na+-K+-ATP-ase remained unchanged. Protein synthesis was stimulated by 75% (against controls). All these phenomena were suppressed when the animals subjected to the action of dinitrophenol were concomitantly treated with the antiacidotic substance, tris (hydroxymethyl) aminomethane.

Acid Phosphatase↗

PubMed1975

Effects of ruthenium red, quinacrine hydrochloride, ethacrynic acid and 2,4-dinitrophenol on the water receptor of the frog tongue.

Effects of some chemicals, which are known as inhibitors of Ca2+-dependent ATPases, on the water receptor of the frog tongue were examined by using single fungiform papilla preparations. When a sufficient amount of ruthenium red, quinacrine hydrochloride, ethacrynic acid or 2,4-dinitrophenol was added to the standard stimulating solution (5mM CaCl2+100 mM NaCl), which has been shown to stimulate sufficiently the water receptor of the frog tongue, no neural response was elicited. The concentrations necessary for 50% inhibition were approximately 3 X 10(-6)M for ruthenium red, 1 X 10(-5) M for quinacrine hydrochloride, 1 X 10 (-3) M for ethacrynic acid and 2 X 10(-4) M for 2,4-dinitrophenol. Organic mercurials, mersalyl acid and p-chloromercuribenzoic acid, had no effect on the nueral response, but repeated application of these chemicals led to a permanent depression in receptor activity. Ouabain had no effect on either the neural response or receptor activity. These observations indicate that the receptor molecule of the frog water receptor has a similar property to that of the Ca2+-dependent ATPase of red-cell membrane in respect to the susceptibility to inhibitors.

Adenosine Triphosphatases↗

PubMed1976

[Influence of dinitrophenol, octanol and toluene upon pH-dependence of ca-ATPase activity of heavy meromyosin].

It is found that dinitrophenol, octanol and toluene produce similar effects on pH-dependence of ATPase of myosin and heavy meromyosin (HMM), i.e. they decrease or remove the neutral suppression of ATPase activity. The appearance of pH-dependence curves is simplified and approaches the form, which is characteristic for the ionisation curve of one; in the last resort two groups, participating in the enzyme activity. The activity of HMM is higher and the zone of the neutral suppression is diminished at low ionic strength, the activation by the modifiers being observed at the significantly lesser degree. CaATPase activation by dinitrophenol, octanol and toluene is suggested to be of the same nature and is accounted for the masking of "the inhibiting" ionizable group of the enzyme with near to neutral pK. This masking may be the result of the conformational changes occuring at the deformation of hydrofobic regions. The ionization of "the activity inhibiting" group of the enzyme depends directly or indirectly on the concentration of potassium chloride and the increase of KCl concentration bring to the inhibition of ATPase activity.

Adenosine Triphosphatases↗

PubMed1979

Effects of 2,4-dinitrophenol on trichomonads and Entamoeba invadens.

1. 2,4-Dinitrophenol (2,4-DNP) in substrate level concentrations (200 microM-1 mM) temporarily inhibits H2 production by Tritrichomonas foetus and Trichomonas vaginalis as well as the accumulation of metronidazole, dependent on its reduction by the two trichomonad species and by Entamoeba invadens. 2. 2,4-DNP competes for the reducing equivalents which are necessary for H2 production or for the reduction of metronidazole, thereby inhibiting these processes. 2,4-DNP is reduced to 2-amino, 4-nitrophenol. 3. 2,4-DNP in concentrations up to 800 microM has no effect on the uptake of O2 by these organisms. 4. 2,4-DNP has some toxicity for T. foetus.

2,4-Dinitrophenol↗

PubMed1979

Effect of 2-4-dinitrophenol on intercellular communication in mammalian cardiac fibres.

The effect of 2-4-dinitrophenol (DNP) on cell communication, in canine Purkinje fibres, was investigated. It was found that DNP (0.5 MM) suppressed the electrical coupling in about 10 min. This effect of DNP was largely due to an increment in intracellular longitudinal resistance. The longitudinal movement of fluorescein (mol. wt. 320) along Purkinje strands, followed with the cut-end method, was also suppressed by DNP (0.5 mM). The decoupling action of DNP was related to release of Ca from intracellular stores and increase in free (Ca)i. The intracellular injection of EDTA reestablished the electrical coupling of Purkinje cells previously uncoupled by DNP. The results described in this paper indicate that cell communication in heart fibres is greatly dependent on the synthesis of high energy phosphate bonds.

Adenosine Triphosphate↗

PubMed1979

Alterations in the survival of X-irradiated cells by 2,4-dinitrophenol depending on ATP deprivation.

The dose-survival curve of cultured melanoma cells was changed by post-irradiation treatment with 2,4-dinitrophenol (DNP). The parameters of the curves were Do = 147 R and n = 5 . 6 for untreated cells and Do = 143 R, n = 7 . 9 and Do = 142 R, n = 2 . 0 for the cells treated with 10(-5) M DNP and 5 x 10(-5) M DNP in phosphate-buffered saline, respectively. The content of ATP in the cell decreased to 5% of the control level after treatment with either concentration of DNP. The recovery of ATP content was rapid and complete after 2 hours' incubation in culture medium after the removal of 10(-5) M DNP, but was retarded and incomplete after 4 hours with 5 x 10(-5) M DNP. Thus prolonged ATP deprivation with a high concentration of DNP results in an inhibition of recovery and a reduction in the n-value.

Adenosine Triphosphate↗

PubMed1977

[Intestinal uptake and transfer of zinc after supplement of 2,4-dinitrophenol and ouabain].

The effect of the inhibitors 2,4-dinitrophenol (DNP) and g-strophantin (ouabain) on the intestinal uptake and cellular transfer of zinc (Zn) and the effect of the organic ligands histidine and EDTA were studied in vitro with everted intestinal sacs of normally maintained rats. Zn was added to the incubation solution as ZnCl2 or as ZnCl2 mixed with histidine in a molar ratio of 200 : 1 and mixed with EDTA in a molar ratio of 1 : 1 or 10 : 1. The DNP in a concentrationof 0.05 mM proved sufficient to greatly inhibit the uptake and transfer of Zn from the solution containing ZnCl2 mixed with an excess of histidine. DNP also reduced Zn absorption when ZnCl2 alone as added. On the other hand, the presence of DNP in the solution containing ZnCl2 with EDTA was found to increase the transfer of Zn and its ligand. In the presence of EDTA, Zn absorption may, therefore, be controlled by the uptake and transfer of the ligand. Ouabain at the contration of 5 mM and 10 mM greatly reduced Zn uptake by the intestinal wall and the celluar Zn transfer from the solution containing ZnCl2 and histidine. There was only a small effect of ouabain on Zn absorption whether ZnCl2 is added alone or with EDTA. The addition of an excess of histidine as ligand to ZnCl2 in the control groups markedly improved Zn absorption. In contrast to this, the addition of EDTA to ZnCl2 reduces the intestinal Zn uptake and increases the transfer of Zn compared to ZnCl2 alone.

Animals↗

PubMed1976

2,4-Dinitrophenol as a specific inhibitor of the breakdown of the actomyosin-phosphate-ADP complex.

2,4-Dinitrophenol (DNP) was found to cause a "clearing response" of myosin B in a medium in which "superprecipitation" of myosin B would otherwise take place. The effect of actin concentration on Mg-ATPase [EC 3.6.1.3] of HMM was studied in the presence and absence of DNP. The results indicate that DNP causes an increase rather than a decrease in the affinity of HMM for actin, and that it causes a decrease only in the actin-activated portion of the Mg-ATPase activity. Using a light-scattering technique, it was shown that neither the ATP-induced dissociation of acto-HMM nor subsequent reassociation is significantly affected by the presence of DNP. As for the formation of the myosin-phosphate-ADP complex in the myosin-ATPase reaction, it was shown that formation of the reactive complex is not affected by DNP. It can thus be concluded that DNP inhibits the decomposition of the actomyosin-phosphate-ADP complex, which is thought to be coupled with superprecipitation.

Actins↗

PubMed1977

Competitive and uncompetitive effects of 2,4-dinitrophenol on ATPase activities of rabbit skeletal actomyosin and myosin.

A kinetic study of the ATPase reactions catalyzed by myosin and actomyosin was carried out by varying the concentrations of ATP and 2,4-dinitrophenol (DNP). Mg-ATPase of myosin in the initial burst and that of actomyosin were both inhibited competitively by DNP. The dissociation contants for the DNP-myosin interaction (Ki) were estimated to be very similar, that is, 4.2 mM in the initial burst of ATP splitting, and 3.3 mM for the actomyosin ATPase. It is therefore suggested that DNP acts at the same site when it inhibits the burst splitting of ATP and the actomyosin ATPase. In contrast, Mg,-Ca-, and EDTA-ATPase activities of myosin in the steady state were all affected uncompetitively by DNP. Moreover, the Ki value for Mg-ATPase of myosin in the steady state was found to be 31 mM, which is much higher than those mentioned above for the initial burst and actomyosin ATPase. It is therefore suggested that the site at which DNP acts to inhibit the burst splitting of ATP is different from the site at which DNP acts to affect Mg-, Ca-, and EDTA-ATPases in the steady state.

Actomyosin↗

PubMed1976

Dinitrophenol, dicoumarol and pentachlorophenol as inhibitors and parasite substrates in the ATP phosphoribosyltransferase reaction.

Adenosine-triphosphate phosphoribosyltransferase from Escherichia coli is inhibited by dicoumarol and pentachlorophenol in competition with ATP. Ki was approximately 60 muM for dicoumarol and 50 muM for pentachlorophenol. Carbonylcyanide m-chlorphenylhydrazine did not seem to have any kinetic effect. Dicoumarol is bound to the extent of 6 sites per enzyme hexamer with a dissociation constant Kd of 50 muM. Dicoumarol and pentachlorophenol partly prevent the binding of ATP and AMP to the transferase. The reverse reaction is inhibited by dicoumarol and pentachlorophenol without changes in [s]0.5 for phosphoribostladenosine trophosphate. Dicumarol, dinitrophenol and pentachlorophenol diminish the yield of phosphoribosyladenosine triphosphate in the transferase reaction apparently by acting as parasite substrates; carbonylcyanide m-chlorophenylhydrazone had no effect.

ATP Phosphoribosyltransferase↗

PubMed1975

Transient repression of catabolite-sensitive enzyme synthesis elicited by 2,4-dinitrophenol.

Transient inhibition of catabolic enzyme synthesis in Escherichia coli occurred when a low concentration of 2,4-dinitrophenol (DNP) was simultaneously added with inducer. Using mutant strains defective for gamma-gene product or constitutive for lac enzymes, it was found that the inhibition is not due to the exclusion of inducer by uncoupling. The addition of cyclic adenosine 3',5'-monophosphate overcame repression. The components of the lac operon coordinately responded to DNP inhibition. From deoxyribonucleic acid-ribonucleic acid hybridization experiments, it was found that the inhibition of beta-galactosidase induction occurred at the level of messenger ribonucleic acid synthesis specific for the lac operon. It seems probable that DNP represses induction in a similar manner to that of transient repression observed upon the addition of glucose. Furthermore, it was found that transient repression disappeared if cells were preincubated with DNP before induction. This indicates that new contact of cells with DNP is obligatory for transient repression. From these results, it is suggested that the cell membrane may be responsible for regulation of catabolite-sensitive enzyme synthesis.

Biological Transport, Active↗

PubMed1975

Respiratory effects of H+ and dinitrophenol injections into the brain stem subarachnoid space of fetal lambs.

Mock cerebrospinal fluid (pH 5.37-8.38) or 2,4-dinitrophenol (DNP) (0.15-1.5 mg) was injected into the subarachnoid space of the ventral brain stem of exteriorized fetal sheep. Changes in pH on the ventral surface of the medulla did not stimulate respiratory efforts or induce significant cardiovascular changes. The respiratory response to DNP injections ranged from no response to prolonged rhythmic ventilation that was independent of the peripheral chemoreceptors or the control arterial pH and blood gas tensions. This inconsistency suggests an effector site somewhat removed from the immediate surface of the medulla. The heart rate and blood pressure were not affected. It is concluded that increased H+ concentration in the extracellular fluid of the fetal ventral medulla does not initiate respiration, and any respiratory response to metabolic inhibitors applied to this area therefore is not attributable to a secondary change in surface pH.

Animals↗

PubMed1975

Inhibition of thyroxine binding to adenohypophysial proteins in vitro by 2,4-dinitrophenol administered in vivo.

Male and female rats were given oestradiol benzoate (1 mg as a microcrystal aqueous suspension i.m. twice a week), 0.0033% 2.4-dinitrophenol (DNP) in their food (about 1 mg/rat/day), or 0.1% DNP in their food (about 30 mg/rat/day), or both oestradiol and DNP. The smaller DNP dose mildly stimulated food consumption and did not affect body weight. The larger dose strongly inhibited food consumption in the first two weeks of the experiment; consumption then returned to the control level, but body weight fell markedly at the same time. After 3 weeks' administration of both the small and the large dose of DNP, adrenal weight in the males was raised and the weight of the gonads was unchanged. The large DNP dose severely reduced the weight of the seminal vesicles and the uteri. It also inhibited the accumulation of radioiodine in the thyroid of both males and females. Isolated administration of the oestrogen raised adrenal weight in the males and ovarian and uterine weight in the females; it reduced the weight of the testes and seminal vesicles. These reactions were not affected by DNP. A pronounced oestradiol-induced increase in the weight of the adenohypophyses was accompanied by raised thyroxine binding to the adenohypophysial proteins in vitro. DNP inhibited the growth reaction of the adenohypophysis to the oestrogen only slightly and non-significantly, but significantly inhibited the thyroxine binding reaction to the adenohypophysial proteins in vitro. By itself, DNP had no effect on adenohypophysial weight, but reduced thyroxine binding to the adenohypophysial proteins in vitro, especially in males. The effect of DNP was similar to that of thyroxine observed in earlier experiments; nothing is known of its mechanism.

Adrenal Glands↗

PubMed1977

[Effect of maintaining the grassfrog sartorius muscle in a 0.002 M solution of alpha-dinitrophenol on its sensitivity to a 0.004 M solution of that substance].

A study was made of the effect of a preliminary maintenance of m. sartorius of Rana temporaria in 0.002 M alpha-dinitrophenol (alpha-DNP) on the resistance of muscles to 0.004 M concentration of this substance. The incubation of muscles in 0.002 M alpha-DNP for 10--20 min results in a statistically significant increase in their resistance to 0.004 alpha-DNP (24.8--30.7%). The highest increase in resistance was observed after a 20 minutes' maintenance of muscles. Therefore on studying the effect of 0.002 M alpha-DNP on the resistance of muscles to the injurious concentrations of chloral hydrate (0.08 M), ethanol (3.48 M), or 36 degrees, the muscles were maintained in the inhibitor for 20 minutes. In the case of a 20 minutes' maintenance of muscles in 0.002 M alpha-DNP, their resistance to chloral hydrate increased by 24.8%, whereas that to ethanol or heating decreased by 23.3 and 37.8--64.6%, respectively.

Animals↗