Respiration, inhibition

Respiration is a ubiquitous and complex oxidative mechanism that conserves energy, liberated by the catabolism of molecules such as carbohydrates, through the production of ATP from ADP and orthophosphate. Several component reaction sequences can be identified. 

Respiratory inhibitors not only deprive the organism of the major end-product, ATP, but may interfere with the production of other vital synthetic intermediates. Several sites of action have been identified for fungicides. 

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Chen et al. state that dendrobine produces moderate hyperglycemia, diminishes cardiac activity in large doses, lowers blood pressure, depresses respiration, inhibits isolated rabbit intestine and contracts isolated guinea-pig uterus. It has a weak analgesic, antipyretic action. Chen and Rose found that the convulsions induced by injection of dendrobine can be controlled by use of sodium isoamylethylbarbiturate they appear to be central in origin due to action on the cord and medulla. 

There are data available on biodegradation (for surface water) from tests conducted according to OECD 301F (respiration inhibition). These data are outlined in Table 6. 

Table 6 Results of biodegradation according to respiration inhibition test OECD 301F.

Sperm 65,400 exposure) none dead during exposure Respiration inhibited 50% in 20 min 23... 

Historically, respirometers have been used for wastewater biodegradability evaluation. More recently [52], a mobile on-line respirometer was proposed and tested for monitoring the activated sludge inhibition due to industrial discharges in a sewer network. A derived portable device called a Baroxymeter [53], based on monitoring the respiration of a bacterial culture by pressure measurements and using respiration inhibition as a toxicity alert, was proposed for the rapid detection of the toxicity effect of some toxic substances. 

Klecka GM, Landi LP, Bodner KM. 1985. Evaluation of the OECD activated sludge, respiration inhibition test. Chemosphere. 14 1239-1251. 

Respiration inhibition kinetics analysis (RIKA) involves the measurement of the effect of toxicants on the kinetics of biogenic substrate (e.g., butyric acid) removal by activated sludge microorganisms. The kinetic parameters studied are max> the maximum specific substrate removal rate (determined indirectly by measuring the maximum respiration rate), and Ks, the half-saturation coefficient [19]. The procedure consists of measuring with a respirometer the Monod kinetic parameters, Vinax and Ks, in the absence and in the presence of various concentrations of the inhibitory compound. 

Some strains survived during 10-day exposure Growth inhibition Respiration inhibited... 

Yoshioka Y, Nagase H, Ose Y, Sato T. 1986. Evaluation of the test method "activated sludge, respiration inhibition test" proposed by the OECD. Ecotoxicol Environ Saf 12(3) 206-212. 

Fluorocitrate is therefore a pseudosubstrate. As well as inhibiting cellular respiration, inhibition of the TCA cycle will also reduce the supply of 2-oxoglutarate. This may decrease the removal of ammonia via formation of glutamic acid and glutamine, and this might account for the convulsions seen in some species after exposure to fluoroacetate. The toxicity is manifested as a malfunction of the CNS and heart, giving rise to nausea, apprehension, convulsions, and defects of cardiac rhythm, leading to ventricular fibrillation. Fluoroacetate and fluorocitrate do not appear to inhibit other enzymes involved in intermediary metabolism, and the di- and trifluoroacetic acids are not similarly incorporated and therefore do not produce the same toxic effects. 

Cryptopine was isolated by Smiles (579) from opium in 1867. Its effect (580) is in many respects similar to that of papaverine and berberine. In dogs it produces hypotension, inhibition of cardiac activity, stimulation of respiration, inhibition of faradization of the vagus, and decrease in the oculocardiac reflex in rabbits, it produces relaxation of the skeletal muscle (581). For guinea pigs the LD100 s.c. was found to be 160 mg/kg (582). Mercier el al. (583, 584) reported the effect of cryptopine on the intestine, the nervous system, blood pressure, cardiac activity, and respiration to range between that of papaverine and berberine. 

Bacterial oxygen consumption, algal fluorescence, microbial respiration inhibition... 

Explosivity Acute inhalation toxicity Bacterial respiration inhibition assay... 

OECD] Organization for Economic Cooperation and Development. 1984. Activated sludge, respiration inhibition test, test guideline 209, adopted 4 April 1984. 

Fig. 7.1. Idealized dose-response relation between measured toxic effect, e.g., respiration inhibition, and concentration of test substance or effluent.

Fig. 7.2. Activated sludge respiration inhibition test. Oxygen uptake due to addition of synthetic sewage to activated sludge (A) with test effluent and (B) with tap water.

EC C.IL Biodegradation Activated sludge respiration inhibition test. Directive 67/548/EEC, AnnexV.(1988)... 

Fig. 10.3. The relationship between the proton motive force (pmf) and the respiration (thermogenesis) of brown fat mitochondria the effect of GDP. The membrane potential and proton gradient were determined by ion distribution methods. It is seen that, with increasing concentrations of GDP, the pmf is increased. However, not until the pmf exceeds about 150 mV is the respiration inhibited. (Adapted from Nicholls [5] for details see this paper.)...

M. Taniguchi, Y. Yano, E. Tada, T. Tanaka, S. Oi, H. Haraguchi, K. Hashimoto and I. Kubo, Potentiation by polygodial of the respiration inhibiting activity of maesanin, Agric. Biol. Chem., 53 (1989) 1525-1530. 

Activated Sludge, Respiration Inhibition Test (original guideline, adopted April 4, 1984)... 

Figure 3.1.5 Range of EC50 values obtained with Respiration inhibition test using 3,5 dichlorophenol...

For the Respiration Inhibition (RI) test performed routinely at the aforementioned laboratory the range of EC50 values obtained over a period of several months ranged from 4.5 to lO.Omg l-1. The AQC plot of these values is given in Figure 3.1.5. 

The MTC values for the various effluents samples tested in the trial ranged from 5 to 48%. Effluents can exhibit a wide range of toxicities. Comparison of the results with nitrification and respiration inhibition tests where applicable showed that the MARA detected toxicity. 

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