Effect Of DNP Research Articles

Electron Microscopy of Clam Myocardium Under Normal and Experimental Conditions

The effect of 2,4-dinitronhenol (DNP) on the fine structure of the myocardium of several vertebrates has been reported by DiDio. We have studied the effects of DNP and lowered oxygen tension on the myocardium of a fresh water clam, an invertebrate.The clam, Amblema plicata (Say, 1817), was used in this investigation. All specimens were maintained in stream water saturated with oxygen unless otherwise noted. Control and experimental animals were opened and the still-beating heart fixed in cold, buffered 1.2% osmium tetroxide. Small blocks of ventricle were dehydrated through an ethanol series, equilibrated in propylene oxide, and embedded in Araldite.

The cataractogenic activity of 2,4-dinitrophenol in ducks and rabbits

Because of an increasing interest in the effects of drugs and other chemicals on the eye, a study has been conducted on the cataractogenic activity of 2,4-dinitrophenol (DNP). Hitherto this effect of DNP has been considered to be specific for fowl and man only. The results reported here show that mature rabbits develop cataracts when DNP is instilled in the conjunctival sac or injected into the posterior chamber of the eye. Furthermore, lenses obtained from mature or immature rabbits, as well as ducks, develop cataracts when incubated in media containing DNP. In immature rabbits, cataracts develop following the intraperitoneal administration of DNP; the rabbit's susceptibility diminishes with age. It has been concluded that the apparent species specificity is related to a difference in the rate of clearance of DNP from the blood or to the presence of a blood-aqueous humor DNP barrier. The implications of these results in toxicologic investigations are discussed.

Induction of tension wood by 2,4-dinitrophenol and auxins

The effect of DNP and auxins on the development of the secondary xylem in erect stems ofAcer rubrum was studied. DNP affected the development of the secondary xylem only locally in the treated internode. Tension wood is formed in the stem below the DNP treatment site whereas above the application site the development of tracheary elements is altered. InAcer rubrum seedlings that were treated with auxin, especially at low concentrations, a thick ring of tension wood is developed in the erect stem below the treatment site. Previous suggestions that the formation of tension wood in arborescent angiosperms is a developmental response to auxin deficiency are discussed in terms of the induction of tension wood inAcer rubrum by DNP and auxins.

Sodium-stimulated adenosine triphosphatase activity of rat brain mitochondria.

Abstract The endogenous ATPase activity of rat brain mitochondria was stimulated 30‐50 per cent by 15‐50 mm concentrations of NaCl or Na acetate. The Na stimulation was completely abolished by small amounts of oligomycin but unaffected by ouabain. The differential effects of these inhibitors indicated that the Na‐induced ATPase activity did not result from microsomal or synaptosomal contamination of mitochrondria. Sodium salts decreased the stimulatory effects of DNP, gramicidin, or Ca, but not that of Mg on the endogenous ATPase activity. These interactions were specific for Na+ as the corresponding salts of K+ did not affect the endogenous ATPase or inhibit the DNP‐stimulated ATPase activity except at high concentrations. The Na‐induced increases in ATPase activity and respiration were more sensitive to aging of the mitochondria than were ADP/O and respiratory control ratios, or the DNP‐induced ATPase activity. These results suggest that Na+ may interact in brain mitochondria with the same high‐energy intermediate of oxidative phosphorylation proposed for DNP and Ca.

Effects of temperature and dinitrophenol on the uptake of potassium and sodium ions in Ricinus communis roots

Detopped root systems of Ricinus communis plants were used for the study of the effects of temperature and DNP on the uptake of K and Na ions supplied as KNO3 and NaNO3.When K and Na ions were offered together in equivalent concentrations, the steady state uptake rates for K(+) and Na(+) at 23 to 25° gave a K(+)/Na(+) ratio of 3. Increasing the Na(+) concentration relative to K(+) 3-fold did not alter the preferential uptake of K(+). The uptake of K(+) was more sensitive to temperature in the range 10 to 40° and to the application of DNP at 1.5x10(-4) M than was the uptake of Na(+). When NaNO3 was the only salt supplied Na(+) uptake became more sensitive to DNP than when both K(+) and Na(+) nitrates were supplied. Prolonged application of DNP led to net K(+) efflux from the roots, even when no K(+) was being supplied to the roots. Net Na(+) efflux under the influence of DNP occurred only in roots previously grown on Na-containing nutrient medium.The different responses of the K(+) and Na(+) uptake processes to temperature and DNP suggest the operation of different uptake mechanisms for K(+) and Na(+) These results have been considered in relation to the recent concept of dual mechanisms for the absorption of alkali cations by plant tissues.

Effects of cyanide, amytal, and DNP on renal sodium absorption.

Effects of cyanide, amytal, and DNP on renal sodium absorption.

The effect of DNP on the resting potential and ionic content of some insect skeletal muscle fibres

1. 1. Application of 0.5 mM DNP to muscle fibres of Periplaneta americana and Sphinx ligustri results in a triphasic decline in their resting potential. 2. 2. Over the 6 hr of the experiment, potassium leaves the muscles of Periplaneta, and sodium and chloride enter. The concentration of sodium and potassium in muscles of Sphinx tends to approach that of the external medium. The curves relating these ionic movements to time are monophasic, and the alteration in resting potential cannot be wholly ascribed to them. 3. 3. It is evident that the resting potential in these muscles depends on oxidative metabolism to a considerable extent. The question of whether active transport of ions or active maintenance of membrane permeability is responsible for maintaining the resting potential of normal fibres is discussed.

The Effect of 2,4‐Dinitrophenol on Translocation in the Phloem

AbstractThe effect of 2,4‐dinitrophenol (DNP) on sucrose‐14C transport in Soya seedlings has been analysed. The aim was to distinguish between an effect of the inhibitor on sugar movement within the phloem sieve tubes themselves, and on the prior steps of uptake and secretion of sugar into the conducting cells.DNP drastically inhibited sucrose‐14C transport if it was applied to the 14C‐treated leaf immediately before, or during, 14C supply. Transport was also strongly inhibited if DNP was applied along the translocation path while the 14C‐treated leaflet was still in position on the plant. When, bowever, DNP was applied through the cut petioles of the primary leaves after removal of the 14C‐treated terminal leaflet of the first trifoliate leaf, no inbibition was observed. On the contrary, transport appeared to have been promoted: significantly more 14C disappeared from the upper regions of DNP‐treated plants as compared with controls, while in the lower plant parts more 14C accumulated. Different rates of synthesis of sucrose‐14C into non‐alcohol‐soluble compounds could not account for this result. A similar stimulatory effect was observed when DNP was applied to the cut petiole of a primary leaf opposite that treated with 14C.Several indications were obtained that 14C which has reached the lower parts of the plant may circulate upwards again through the phloem within about 15 minutes. When sucrose‐14C was introduced into the roots via the xylem, both DNP treatment and prior steam girdling resulted in the apparent accumulation of 14C in the lower plant parts. the results would be compatible with DNP inhibition of upwards movement in the phloem. DNP might also have affected sugar uptake processes in cells neighbouring the translocation path.It is concluded that the inhibitory effect of DNP on downwards phloem transport reported by earlier workers was probably due to an effect on uptake and/or secretion into the sieve tubes, not to an effect on the conducting cells themselves. Modern theories for phloem transport are discussed in the light of these findings.

Analysis of the effect of alpha-dinitrophenol on cleavage and development of the sea urchin embryo.

The influence of DNP on the developing sea urchin embryo was studied by means of time-lapse cinematography and staining methods. In the concentrations of DNP which affect oxidative phosphorylation cleavage is rapidly brought to a standstill. DNP inflicts morphological changes of the mitochondria, which also show a lowered affinity for Janus green B. Some new aspects on the effect of DNP on morphogenesis are discussed.

Biochemical Aspects of Juvenile Hormone Action in the Adult Locusta Migratoria by

Biochemical Aspects of Juvenile Hormone Action in the Adult Locusta Migratoria by

Steigerung der absoluten ATP-Umsetzungsrate in der isolierten Skeletmuskulatur unter dem Einflu� von 2,4-Dinitrophenol

1. After a 15 min treatment at 20°C with 5 · 10−4 M 2,4-dinitrophenol (DNP) the creatine phosphate (CP) content of the isolated frog muscle (M. rectus abdomn.) is reduced by 70–80% of the normal. The ATP-fraction displays no significant diminution in concentration after this period of DNP-poisoning. 2. The elevated level of intracellular orthophosphate (Pi) (resulting from CP-breakdown) reduces the P32O4-uptake from the extracellular volume. The observed blocking effect of DNP on P32-incorporation in the terminal phosphoryl group of ATP (ATP-Pγ) is due to a deficiency in intracellular tracer-Pi (P32O4) and is not to be interpreted as general inhibition of ATP-synthesis. Use of H2O18 eliminates the disturbing influence of the transmembrane orthophosphate gradient. 3. The short diffusion time for water leads to almost ideal constancy in supply of tracer-Pi (PO418) (by H2O18 ⇋ PO4 exchange) to the intracellular volume. Under this steady-state condition it was found that DNP a) intensifies the O18-labelling of the Pi-fraction (by enhancement of dephosphorylations) and b) causes a marked increase in the O18-incorporation in the total ATP-fraction (by enhancement of synthesis). It is noteworthy that the enhancement of O18-incorporation in CP by DNP is much less than that in ATP-Pγ. The resulting difference in O18-labelling between these two phosphoryl groups seems to be a characteristic DNP effect in muscle. 4. The absolute turnover rates were calculated using a simple kinetic model20, 26 which takes the ATP-independent H2O ⇋ PO4 exchange into account. The biological half-life of ATP-Pγ in the DNP-treated frog muscle is 69 sec at 20°C, that of ATP-Pβ is 256 sec and that of CP is 130 sec. The Pi-fraction has a half-life at 20°C of 45 sec. Hence in the presence of DNP the turnover rate of ATP-Pγ is 10 times and that of ATP-Pβ is 27 times faster than in the control muscle devoid of DNP (see reference20). The results are discussed in relation to known DNP effects (ATPase activation, uncoupling, inhibition of the Pasteur-effect) in other biological systems.

Effects of dinitrophenol and oligomycin on the coupling between anaerobic metabolism and anaerobic sodium transport by the isolated turtle bladder.

Dinitrophenol (1 x 10(-5)M) has been found to inhibit anaerobic sodium transport by the isolated urinary bladder of the fresh water turtle. Concurrently, anaerobic glycolysis was stimulated markedly. However, tissue ATP levels diminished only modestly, remaining at approximately 75% of values observed under anaerobic conditions without DNP. The utilization of glucose (from endogenous glycogen) corresponded closely to that predicted from the molar quantities of lactate formed. Thus the glycolytic pathway was completed in the presence of DNP and if ATP were synthesized normally during glycolysis, synthesis should have been increased. On the other hand, the decrease in Na transport should have decreased ATP utilization. Oligomycin did not block sodium transport either aerobically or anaerobically, but ATP concentrations did decrease. When anaerobic glycolysis was blocked by iodoacetate, pyruvate did not sustain sodium transport thus suggesting that no electron acceptors were available in the system. Two explanations are entertained for the anaerobic effect of DNP: (a) Stimulation by DNP of plasma membrane as well as mitochondrial ATPase activity; (b) inhibition of a high energy intermediate derived from glycolytic ATP or from glycolysis per se. The arguments relevant to each possibility are presented in the text. Although definitive resolution is not possible, we believe that the data favor the hypothesis that there was a high energy intermediate in the anaerobic system and that this intermediate, rather than ATP, served as the immediate source of energy for the sodium pump.

Influence of Light Regime on the Toxicity and Physiological Activity of Herbicides

The responlse of plants to certain herbicides is inifltieniced by the light coniditions precedinig or followinig applicatioln of the herbicide (14, 15, 16. 18, 21t) but the physiological basis for the differential activity of certaini herbicidal compounds in relation to the light conditions tunider which they are applied is uincertaini in most cases. This paper deals witlh 2 sutch lighlt-infltuence(d responises of plants to herbicides. Onle series of experimiients was perforn,ed to study an observation first reported by Salisbury (21) that plants treated with 2 4-dinitrophenol (DNP) are considerably more injured when the plants receive darkness after treatment than when they are exposed to light following application of the compound. Another series of investigations deals with the physiological activity of sodiumii 2, 4-dichlorophenoxyacetic acid (2, 4-D) in pllants as iniflueenced by uiltraviolet light anid the light regime to which plants are subjected after UVirra(liation and auxin treatmenit. There are many reports in the literature concerninig the effects of DNP on photosynthesis and photophosphorylationl (2, 17, 26), respiration anid oxi(lative phosphorylatiol (i 5 7), and other energyrequiring processes involvingo hi-h eniergy phosphate comlpounds (1, 19). In such stutdies the toxicity of DNP anid related col)ipounids is often marked!y infltueniced by the pH at which the material is applied to plants (23), an(d the carrier in which the material is applied (8). Salisbury (21) has suggested that the physiological basis for the differential toxicity of DNP to plants suibjected to light or dlarkness after DNP treatment may lie in a difference in senisitivity of the oxi(lattive and photosynithetic phosphorylationi mechaniismiis to DNP. Sinice DNP is more phytotoxic wheni its application is followed by (larkiess, D)NP mlay be inhibiting oxi(lative phosphory!ation but lnot photoplosphorytatioll. T hus, the level of ATP in plaints left in the (lark after DNP treatment wvould be lowered anid result in observable plant damage, but plants treated anid left in the light might avoid injury. Ohmura (17) and Wessels (26) have inideed demiionstrate(d a pathway of photoIhosphorylation whiclh is inisenisitive to DNP at concenitrations which inhibit oxi(lative phosphorylationi. De Zeeuw and Leopold (10) have reported that tomato plants irradiated with UV light for short periods of time do not exhibit the normal epinastic responses following auxini (iiapthalene acetic acid) treatment. IJltraviolet radiationi given before auxini treatment was more effective in preventinig epinasty in atuxin-treated plants than UV radiation given after auxini treatmiient. In other experimiients they (letermiined that UV ra(liation did not significantly affect the uptake of auxini. They concluded that the prevention of auxin responises in UV irradiate(l plants was due to a preventioni of auxin actioni insi(le the plants. It has beeni noted freqtuently that the physiological anid histological effects of UV on plant anid animal tissues can be overcomiie or reversed by wlhite light. For example, the inhibitory effects of UN' light oni such videly diverse processes as chlorophyll destruction (25), inactivation of bacteriophages (11), and growth of fuingi (12) can be reversedl by white light followving UV radiation. The mechanism of this photoreversal is still obscure, and experimental restults are diffictult to interpret (ltle to the multiplicity of physiological processes in plants affecte(d 1w UNV radiation. The present work was conducted to elaborate uponl these light-infltuenced responises of pllants to 2. 4-D, DNP, anid related comiipotunids alld shed(l ne light oln the plhysiological basis for the phytotoxicity of these compounds.

The Effect of ATP on Uptake of Monovalent Cations and Anions by Red Beet Slices

Externally added ATP inhibits sodium and potassium uptake by red beet tissue; this inhibition seems to be competitive. The effects of DNP and ATP additions on cation uptake were found to be additive. ATP did not inhibit chloride and bromide uptake. The results and their implications are discussed.

EFFECTS OF INHIBITORS ON CONTRACTIONS OF NORMAL AND DYSTROPHIC MOUSE MUSCLES.

Exposure to 0.05 mm 2,4-dinitrophenol (DNP), 1 mm NaN3, and 1 mm KCN reveals the following differences between normal and dystrophic excised, curarized gastrocnemius muscles of mice of strain 129. DNP briefly enhances twitch but not tetanus tension in rested dystrophic mice before depressing both tensions. In rested normal mice these tensions decline immediately. NaN3 reduces tensions in rested normal mice for 30 min; slow recovery follows. Half-relaxation rate is also reduced. In rested dystrophic mice tension does not recover from depression in NaN3, and the relaxation rate increases. During fatigue, tension output in dystrophic declines less rapidly than in normal mice, regardless of inhibitors. NaN3 accentuates fatigue-associated increases of contraction rate in dystrophic mice, but accelerates the usual reduction of this rate in normal ones. The two muscle groups also show quantitative differences in their responses to the inhibitors. Except for some DNP effects, all changes are reversible. Known actions of the inhibitors account only inadequately for these observations, and no clearly identifiable metabolic lesions of dystrophic muscles emerge.

EFFECT OF DNP ON NEURO-MUSCULAR JUNCTION OF FROG.

Endplate potential can be regarded as one of the indications of the transmitter output in the nerve terminal. By observing the pattern of successive e. p. p. evoked by tetanic stimulation of the frog nerve under various conditions, the report on the state of nerve terminal concerning the quantity of transmitter released was given by Wakabayashi and Iwasaki in this jounal. In the present report the characteristic effect of a metabolic inhibitor: 2-4 DNP on e. p. p. pattern is presented, and the mode of action of this drug different from other inhibitors or excess potasium is discussed. This drug reduces e. p. p. size but increases m. e. p. p. frequency as reported by Kraatz and Trautwein. Here the marked facilitation followed by steep depression showing a bell pattern was observed. The train of e. p. p. decreased in size by every repetition of tetaniza-tion. It indicates the exhaustion of available transmitter, and really long time was necessary to recover the original pattern. The bell pattern was characteristic of 2-4 DNP, and the action of other inhibitors, Ca++ deficiency or Mg++ addition did not bring about such an effect. From this, the mode of action of DNP cannot be explained only by the inhibition of oxydative trans-phosphyrolyation or reduced output of transmitter. On the other hand the Ach sensitivity was found unchanged in DNP muscle by measuring the depolariza-tion. In fact, m. e. p. p. in DNP muscle showed increase in frequency or burst at the certain decreased level of resting potential. Therefore, the site of action of DNP may not be postsynaptic and some specific inhibition of synthesis or supply of transmitter is suggested.

The Interrelation between the Effects of 2,4-Dinitrophenol and of Substrate Concentration on the Rate of Exogenous Respiration

1. The specific activity of the C02 evolved by sunflower hypocotyl segments supplied with labelled glucose or glutamic acid is related to the external concen tration by a rectangular hyperbola over a concentration range of approx. 2-60 mM. The overall respiration rate over this range is approximately 15 percent, above that of a buffer control, and rises only slightly with increasing external concentration. 2. The curve for total exogenous substrate respired is also close to a rectangular hyperbola over this concentration range. 3. 2,4-dinitrophenol (DNP) reduces the slope of the hyperbola for specific activity, but not its maximum value. Increasing the glucose concentration while maintaining the DNP concentration constant reduces the degree of inhibition. 4. The effect of DNP on absolute amount of exogenous substrate respired depends on the external concentration of the substrate. At lower concentrations, absolute exogenous respiration is inhibited: at higher concentrations, it is stimulated. 5. The results have been analysed with the object of determining whether the respiratory sites lie in the 'sugar free space' of the cell. Kinetic analysis indicates (a) that exogenous substrates do not diffuse to these sites through an appreciable diffusion barrier ; (?>) that there is no evidence for an active transport step ; and (c) that the data accord well with the view that exogenous substrates diffuse freely to the respiratory sites where they compete on equal terms with endogenous substrates.

QUANTITATIVE STUDIES OF THE EFFECT OF ORGANIC SUBSTRATES AND 2,4-DINITROPHENOL ON HETEROTROPHIC CARBON DIOXIDE FIXATION IN HYDROGENOMONAS FACILIS.

McFadden, Bruce A. (Washington State University, Pullman), and H. Robert Homann. Quantitative studies of the effect of organic substrates and 2,4-dinitrophenol on heterotrophic carbon dioxide fixation in Hydrogenomonas facilis. J. Bacteriol. 86:971-977. 1963.-Whole cells of Hydrogenomonas facilis under heterotrophic conditions fixed levels of C(14)O(2) which depended upon the nature of the carbon source being oxidized. It was established that oxidative rates varied as a function of p(CO2). Therefore, all studies were conducted in the presence of 1.5 mole% CO(2) in the gas phase. With glucose-grown cells supplied with glucose as substrate, the heterotrophic fixation was curtailed 98% by the addition of 8.3 x 10(-4)m 2,4-dinitrophenol (DNP). A coupling between reductive fixation of CO(2) and heterotrophic oxidation of substrate is consistent with the observed effect of DNP. The efficiency of coupling of fixation with oxidation was studied for acetate, d-glucose, l-glutamate, d,l-lactate, d-ribose, and succinate as substrates. Kinetic studies showed that the efficiency of coupling (expressed as disintegrations per minute of C(14) per microliter of O(2)) was initially time-variable for all substrates; however, it approached a constant value after 30 to 45 min for acetate, glutamate, lactate, and succinate. The initial variation of the ratio with time was due primarily to C(14)O(2) uptake, which was nonlinear with time. Control studies in the absence of exogenous substrate indicated that CO(2) fixation may also be linked to oxidation of endogenous stores accumulated during heterotrophic growth. d-Ribose appears to be the most promising substrate for short-term fixation studies owing to the rapid incorporation of C(14) and the unusually low endogenous fixation rate by cells grown on ribose. Calculations reveal that, after isotopic equilibrium has occurred, the amount of CO(2) utilized during glucose oxidation is almost 50% of O(2) uptake during the same interval. Even during succinate oxidation, which was shown to be coupled much less effectively with CO(2) fixation, the CO(2) utilized during the same interval is 8% of O(2) uptake.

Radiation as an Uncoupling Agent in Frog Muscle

X ray exposure of 100,000 r in vitro increases the rate of oxygen consuinption of frog sartorius muscles in Ringer solution from 3.3 to 7.1 micromoles oxygen per gram muscle per hour. Addition of iodoacetic acid after irradiation eliminates this increase. Addition of maximally uncoupling concentrations of dinitrophenol after irradiation also eliminates any radiation effect on O/sub 2/ uptake. Addition of partially uncoupling concentrations of DNP after irradiation results in additive effects of radiation and DNP on O/sub 2/ uptake. These resuits can be explained by the hypothesis that this dose of radiation increases oxygen uptake by partially uncoupling oxidation from phosphorylation, without significantly damaging other parts of the oxidative chain. (auth)

Mechanisms of Thermal Responses to 2,4-Dinitrophenol

2,4-Dinitrophenol (DNP) produced a consistent hyperthermia in lightly restrained rats at ambient temperatures above 20 to 22°C, and a hypothermia at lower ambient temperatures. DNP failed to affect body temperature in rats at a low ambient temperature. DNP produced a smaller increase in oxygen consumption of lightly restrained rats at lower ambient temperatures. In contrast to its effects in rats, DNP in doses of 3.0 and 20 mg/kg did not affect the body temperature of lightly restrained dogs at low ambient temperatures (10 and 4°C). Visible shivering was not noticeably influenced by the dose of 3.0 mg/kg but was greatly diminished by 20 mg/kg. A relative hyperthermia was produced in dogs completely paralyzed with a neuromuscular blocking agent at all ambient temperatures studied (5 to 20°C). The hyperthermia was due to increased heat production which was not significantly different at different ambient temperatures. Intracarotid infusion of a small dose of DNP in curarized dogs over a 10-minute period produced a much smaller increase in oxygen consumption than did intravenous infusion of the same dose. These results indicate that the hypothermic effect of DNP probably is due to both a centrally-mediated inhibition of the skeletal muscle thermogenic response to cold and to a reduced metabolic effect of DNP at low ambient temperatures. The hyperthermic effect of DNP, on the other hand, probably can be attributed entirely to a peripherally-mediated thermogenic action.