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PubMed2004

Ammonia excretion in aquatic and terrestrial crabs.

The excretory transport of toxic ammonia across epithelia is not fully understood. This review presents data combined with models of ammonia excretion derived from studies on decapod crabs, with a view to providing new impetus to investigation of this essential issue. The majority of crabs preserve ammonotely regardless of their habitat, which varies from extreme hypersaline to freshwater aquatic environments, and ranges from transient air exposure to obligate air breathing. Important components in the excretory process are the Na+/K+(NH4+)-ATPase and other membrane-bound transport proteins identified in many species, an exocytotic ammonia excretion mechanism thought to function in gills of aquatic crabs such as Carcinus maenas, and gaseous ammonia release found in terrestrial crabs, such as Geograpsus grayi and Ocypode quadrata. In addition, this review presents evidence for a crustacean Rhesus-like protein that shows high homology to the human Rhesus-like ammonia transporter both in its amino acid sequence and in its predicted secondary structure.

Ammonia↗
PubMed2001

The cultured branchial epithelium of the rainbow trout as a model for diffusive fluxes of ammonia across the fish gill.

A novel branchial epithelial preparation grown in L-15 medium in culture was used as a model system for understanding the diffusion of ammonia across the gills of the rainbow trout Oncorhynchus mykiss. The epithelium is known to contain both respiratory and mitochondria-rich cells in the approximate proportion in which they occur in vivo and to exhibit diffusive fluxes of Na+ and Cl- similar to in vivo values, but does not exhibit active apical-to-basolateral transport of Na+. Transepithelial resistance and paracellular permeability are also known to increase when the apical medium is changed from L-15 medium (symmetrical conditions) to fresh water (asymmetrical conditions). In the present study, net basolateral-to-apical ammonia fluxes increased as basolateral total ammonia concentration, basolateral-to-apical pH gradients and basolateral-to-apical P(NH(3)) gradients were experimentally increased and were greater under asymmetrical than under symmetrical conditions. The slope of the relationship between ammonia flux and P(NH(3)) gradient (i.e. NH(3) permeability) was the same under both conditions and similar to values for other epithelia. The higher fluxes under asymmetrical conditions were explained by an apparent diffusive flux of NH(4)+ that was linearly correlated with transepithelial conductance and was probably explained by the higher electrochemical gradient and higher paracellular permeability when fresh water was present on the apical surface. In this situation, NH(4)(+) diffusion was greater than NH(3) diffusion under conditions representative of in vivo values, but overall fluxes amounted to only approximately 20% of those in vivo. These results suggest that branchial ammonia excretion in the intact animal is unlikely to be explained by diffusion alone and, therefore, that carrier-mediated transport may play an important role.

Ammonia↗
PubMed2002

Active ammonia excretion across the gills of the green shore crab Carcinus maenas: participation of Na(+)/K(+)-ATPase, V-type H(+)-ATPase and functional microtubules.

Although aquatic animals are generally believed to export nitrogenous waste by diffusion of NH(3) or NH(4)(+) across external epithelia, evidence for active ammonia excretion has been found in a number of species. In the euryhaline green shore crab Carcinus maenas, active excretion of ammonia across isolated gills is reduced by inhibitors of the Na(+)/K(+)-ATPase and vacuolar-type H(+)-ATPase. In addition, a functional dynamic microtubule network is necessary, since application of colchicine, taxol or thiabendazole leads to almost complete blockage of active and gradient-driven ammonia excretion. Actin filaments seem not to play a role in the excretory process. The NH(4)(+)-dependent short-circuit current and the conductance of the isolated cuticle were reduced in a dose-dependent manner by amiloride, a non-specific inhibitor of the Na(+)/H(+) exchanger and Na(+) channels. Combined with an analysis of gill morphology, the strong intracellular but weak apical abundance of V-type H(+)-ATPase and the fact that ammonia flux rates are equal under buffered and unbuffered experimental conditions, our observations suggest a hypothetical model of transepithelial ammonia movement that features active uptake across the basolateral membrane, sequestration in acidified vesicles, vesicle transport via microtubules and exocytosis at the apical membrane.

Amino Acid Sequence↗
PubMed1989

Protective effect of taurine against ammonia-induced gastric mucosal lesions in rats.

We examined the role of gastric ammonia in the development of gastric lesions in rats. Exposure of the gastric mucosa to ammonia (30 mM) produced microscopic injury, but no macroscopic lesion was observed. However, exposure of the stomach to ammonia in rats subjected to ischemia resulted in macroscopic gastric lesions. The macroscopic lesions were markedly inhibited by pretreatment with taurine, a scavenger of hypochlorous acid (HOCI) and monochloramine (NH2Cl). These results indicate that ammonia is deleterious to gastric mucosa, and monochloramine may be involved in the pathogenesis of ammonia-induced mucosal lesions.

Ammonia↗
PubMed1993

Murine cage density: cage ammonia levels during the reproductive performance of an inbred strain and two outbred stocks of monogamous breeding pairs of mice.

The Laboratory Animal Breeders Association guidelines recommend a minimum floor area of 300 cm2 for a monogamous pair of inbred/outbred mice or a trio of inbreds. The mean level of ammonia produced during lactation from BALB/c, TO and CD-1 breeding pairs housed in M2 cages with a floor area of 300 cm2 on Day 4 after cleaning was 30 ppm, 87 ppm and 92 ppm, respectively. All 3 strains of mice, particularly the outbred strains, were subjected to high levels of ammonia as compared with human long-term health and safety occupational exposure limits (25 ppm). However, there is a gradient of ammonia within an M2 breeding cage from the nest (19 ppm), to the food hopper, 77 ppm. By housing CD-1 pairs of mice in RM2 cages which have more than double the floor area of M2 cages (676 cm2), the mean level of ammonia during lactation on Day 4 after cleaning was reduced to 26 ppm. The reproductive performance on inbred/outbred strains of mice has to be equated with cage size (floor area) to maintain acceptable levels of ammonia. It is suggested that the recommended minimum floor areas for breeding mice be reviewed.

Ammonia↗
PubMed2001

Pretreatment with ammonia water for enzymatic hydrolysis of corn husk, bagasse, and switchgrass.

Bagasse, corn husk, and switchgrass were pretreated with ammonia water to enhance enzymatic hydrolysis. The sample (2 g) was mixed with 1-6 mL ammonia water (25-28% ammonia) and autoclaved at 120 degreesC for 20 min. After treatment, the product was vacuum-dried to remove ammonia gas. The dried solid could be used immediately in the enzymatic hydrolysis without washing. The enzymatic hydrolysis was effectively improved with more than 0.5 and 1 mL ammonia water/g for corn husk and bagasse, respectively. In bagasse, glucose, xylose, and xylobiose were the main products. The adsorption of CMCase and xylanase was related to the initial rate of enzymatic hydrolysis. In corn husks, arabinoxylan extracted by pretreatment was substantially unhydrolyzed because of the high ratio of arabinose to xylose (0.6). The carbohydrate yields from cellulose and hemicellulose were 72.9% and 82.4% in bagasse, and 86.2% and 91.9% in corn husk, respectively. The ammonia/water pretreatment also benefited from switchgrass (Miscanthus sinensis and Solidago altissima L.) hydrolysis.

Adsorption↗
PubMedDate not supplied

Susceptibility of ammonia-oxidizing bacteria to nitrification inhibitors.

Activity of nitrification inhibitors to several typical ammonia-oxidizing bacteria isolated recently, i. e. Nitrosococcus, Nitrosolobus, Nitrosomonas, Nitrosospira and Nitrosovibrio species was assayed using 2-amino-4-methyl-trichloromethyl-1,3,5-triazine (MAST), 2-amino-4-tribromomethyl-6-trichloromethyl-1,3,5-triazine (Br-MAST), 2-chloro-6-trichloromethylpyridine (nitrapyrin) and others, and compared to confirm the adequate control of ammonia-oxidizing bacteria by the inhibitors. The order of activity of the inhibitors to 13 species of ammonia-oxidizing bacteria examined was approximately summarized as Br-MAST > or = nitrapyrin > or = MAST > other inhibitors. Two Nitrosomonas strains, N. europaea ATCC25978 and N. sp. B2, were extremely susceptible to Br-MAST, exhibiting a pI50 > or = 6.40. These values are the position logarithms of the molar half-inhibition concentration. The 16S rRNA gene sequence similarity for the highly susceptible 4 strains of genus Nitrosomonas was 94% to 100% of Nitrosomonas europaea, although those of the less susceptible 3 strains of ammonia-oxidizing bacteria, Nitrosococcus oceanus C-107 ATCC19707, Nitrosolobus sp. PJA1 and Nitrosolobus multiformis ATCC25196, were 77.85, 91.53 and 90.29, respectively. However, no clear correlation has been found yet between pI50-values and percent similarity of 16S rRNA gene sequence among ammonia-oxidizing bacteria.

Ammonia↗
PubMed1977

Effect of hydrocortisone on ammonia intoxication in the adrenalectomized rat.

Adrenalectomy induces a hypersensitivity in the rat to ammonia intoxication. Daily injection of hydrocortisone hydrochloride to adrenalectomized rats restored normal sensitivity to ammonia intoxication, with concomitant restoration of liver urea-synthesizing capacity to the normal value. When injected with a large dose of ammonium acetate, hydrocortisone-treated adrenalectomized rats were able to reduce the plasma ammonia concentration much more rapidly than the adrenalectomized control rats. However, neither the increase in liver urea synthesis nor the more rapid decrease in the plasma ammonia concentration were sufficient to explain the protective aciton of hydrocortisone against ammonia intoxication.

Adrenalectomy↗
PubMed1979

[Observation on the air-borne bacteria and ammonia (NS3) gas in laboratory animal facility with rotary heat exchanger].

The number of air-borne bacteria in air ducts and barrierred laboratory animal rooms with the so-called econovent rotary heat exchanger, were checked monthly during a year by the pin-hole sumpler method for air ducts and Koch method for animal rooms. Also, concentration of ammonia was checked with the same samples by gas impinger. No significantly difference in number of air-borne bacteria was seen between before and after passing the econovent. Those passing through HEPA filter was not detected. There were more air-borne bacteria in animal rooms, outside locker room and shower room than in the corridor, utensil storage, inside locker room and pass box. No ammonia were detected in the outdoor, but exhaust air duct after passing the econovent contained very small amount of ammonia. On the other hand, high concentration of ammonia were preserved in the supplying air duct, exhaust air duct and mice and rats rooms, about 86% of ammonia in exhaust air duct returned back into the supplying air duct. No influences on reproduction in mice and rats were recognized.

Air↗
PubMed1995

[Invention of a forced-air-ventilated micro-isolation cage and rack system--environment within cages: temperature and ammonia concentration].

There is little information about microenvironments within laboratory animal cages, although several guidelines on the macroenvironment in laboratory animal rooms have been reported. We have developed a forced-air ventilation system (FVMIS) to improve laboratory animal well-being. In this study, we tested the performance of the FVMIS in terms of temperature and ammonia concentration within cages. Continuous measurement of temperature and ammonia concentration was carried out in FVMIS cages housing 5 rats each. The average temperature within the cages was 22 degrees C to 24 degrees C, and the temperature difference among cages was 0.93 degrees C. The air exchange rate used was 65 changes per hour. FVMIS was capable of controlling the temperature within cages uniformly and accurately with a lower air exchange rate than with the conventional system. The ammonia concentration reached 20 ppm within 9 days in a filtercapped conventional cage, but took 13 to 16 days to reach 20 ppm with FVMIS. It appears that FVMIS is capable of suppressing the ammonia concentration increase in cages, thereby reducing the frequency of cage changes and the stress to laboratory animals when cages are changed. In the present study, it was confirmed that FVMIS contributes not only to microenvironmental control in terms of temperature and ammonia concentration with a lower air exchange rate, but also to animal well-being.

Ammonia↗
PubMed2005

Relative ammonia concentrations, dust concentrations, and presence of Salmoneua species and Escherichia coli inside and outside commercial layer facilities.

Three air contaminants that may have serious health consequences to humans and poultry are ammonia, dust, and aerosolized bacteria. This study measured ammonia concentrations, dust concentrations, and the presence or absence of aerosolized Salmonella spp. and Escherichia coli inside and outside five commercial layer facilities. The average outside ammonia concentration measurements decreased as the distance from the facility increased from 10 to 40 ft. The measurements at 10 ft from the facilities were consistently higher than the average concentrations inside the facilities. The ammonia measurement trends inside of the facilities were affected by the temperature-dependent ventilation systems. Average dust concentrations inside the five facilities were consistently below 2 mg/m3. Three facilities also experienced average outside dust concentrations at all measured distances below 2 mg/m3. Two facilities had relatively high average dust measurements at 10 ft from ventilation fans (32.12 mg/m3 and 75.18 mg/m3). Escherichia coli and Salmonella were isolated from the air inside all five facilities and outside the facilities up to 40 ft from the ventilation fans. In condusion, dust concentrations may pose the largest risk to human and animal health at 10 ft away from the poultry facilities; risks associated with ammonia inhalation are greatest inside facilities during the coolest months of the year; and aerosolized bacteria are found inside and outside poultry facilities, but further work is needed to quantify the bacteria to further assess the health risk related to this issue.

Air Pollutants↗
PubMed1984

Accelerated leucine decarboxylation in the rat brain in relation to increased blood ammonia levels during acute hepatic failure.

Leucine decarboxylation in rat brain was investigated during acute hepatic failure, induced by partial hepatectomy after carbon tetrachloride (CCl4) pretreatment of rats. These rats presented metabolic alkalosis, and had significantly higher levels of arterial blood and brain ammonia than control and CCl4-treated rats. Brain leucine decarboxylation was elevated in rats with hepatic failure. This alteration correlated with arterial blood ammonia concentrations, and probably with elevated brain ammonia levels, as brain ammonia levels were directly related to arterial blood ammonia.

Ammonia↗
PubMed2003

Sensitivity of juvenile freshwater mussels (Lampsilis fasciola, Villosa iris) to total and un-ionized ammonia.

This study evaluated the sensitivity of juveniles of two freshwater unionid mussel species (Villosa iris [Lea] and Lampsilis fasciola [Rafinesquel) to un-ionized and total ammonia. Five concentrations of ammonium chloride were tested using 96-h static-renewal toxicity tests at 12 and 20 degrees C. Based on their respective mean 96-h lethal concentration to 50% (LC50s), V. iris (0.11 mg/ L NH3-N) was more sensitive than L. fasciola (0.26 mg/L NH3-N). At 96 h, significant differences in sensitivity to un-ionized ammonia between the two temperatures were not observed for either species. Comparison of LC50s reported for other aquatic organisms to the 96-h LC50s calculated for juvenile L. fasciola and V. iris shows these two mussel species to be among the most sensitive to un-ionized ammonia. Based on reported levels of un-ionized ammonia in the aquatic environment from anthropogenic sources, un-ionized ammonia may be an important limiting toxicological factor to freshwater mussel populations.

Age Factors↗
PubMed1987

Effects of ammonia on lung stretch receptor activity in the rabbit.

The effects of ammonia on lung stretch receptor activity and respiration were studied in the rabbit. This chemical agent caused rapid and shallow breathings or augmented breaths or their combination. The majority of slowly adapting pulmonary stretch receptors (SRs) following ammonia inhalation increased their activity during both inspiration and expiration. At 30 s after ammonia inhalation, the responses of SR activity in both respiratory phases were grouped into four different types: an increase, no effect, a decrease, and no activity. In the time course of ammonia inhalation, the occurrence of a tonic firing pattern of SR activity preceded by a silent phase of the activity was observed in some SRs. In comparison with the findings of a previous report in the rabbit concerning the discharge pattern of SR activity after ammonia inhalation, the results obtained in this study suggest that some SRs in the rabbit are probably located peripheral to the site of the obstruction in the lung unit.

Administration, Inhalation↗
PubMedDate not supplied

Oxygen fluxes and ammonia removal efficiencies in constructed treatment wetlands.

Ammonia-removal efficiency in constructed wetlands is often limited by the amount of oxygen available in the system. In this study, the oxygen-transfer rates to laboratory-scale, subsurface-flow and free-water-surface constructed wetlands were quantified for two input concentrations of ammonia, 10 and 50 mg nitrogen/L, both with and without Typha latifolia. Rates of oxygen diffusion into the subsurface-flow constructed wetlands were 6.01 to 7.92 g/m2 x d and were strongly correlated with ammonia concentration in the water. In contrast, low oxygen diffusion rates of 1.36 to 1.76 g/m2 x d were observed for the free-water-surface system. The presence of Typha latifolia had small but consistent effects on atmospheric oxygen-diffusion rates and ammonia-removal efficiencies in both the subsurface-flow and free-water-surface systems. The observed small effects were consistent with measurements of oxygen inputs from T. latifolia roots. Only approximately 0.023 g/m2 x d of oxygen was released from roots of T. latifolia, as measured using the titanium (III) citrate buffer method. The results for the ammonia-removal rates of the laboratory-scale constructed wetlands were further verified using pilot-scale constructed wetlands under greenhouse conditions.

Ammonia↗
PubMed1976

The chemical ecology of Biomphalaria glabrata: the effects of ammonia on the growth rate of juvenile snails.

When juvenile specimens of Biomphalaria glabrata were subjected to concentrations of ammonia ranging from 1-100 mug/ml in various media the following effects were observed: the addition of ammonia to borate buffered media caused mortality. Both borate and tris-buffered media caused a decrease in the growth rate of snails when compared with controls in SSW. The growth rates of the snails could be enhanced by increasing the concentration of ammonia to critical thresholds, but further increases beyond these thresholds resulted in growth inhibition. The toxicity of ammonia in ambient water was augmented by an an increase in pH. The possible causation and ecological significance of these effects are discussed. There are indications that the snails are physiologically well-adapted to utilize ammonia when required and also to control its excretion and uptake from the medium.

Ammonia↗
PubMed2005

Splanchnic metabolism of nitrogenous compounds and urinary nitrogen excretion in steers fed alfalfa under conditions of increased absorption of ammonia and L-arginine supply across the portal-drained viscera.

Effects of increased ammonia and/or arginine absorption across the portal-drained viscera (PDV) on net splanchnic (PDV and liver) metabolism of nitrogenous compounds and urinary N excretion were investigated in six catheterized Hereford x Angus steers (501 +/- 1 kg BW) fed a 75% alfalfa:25% (as-fed basis) corn-soybean meal diet (0.523 MJ of ME/[kg BW(0.75).d]) every 2 h without (27.0 g of N/kg of dietary DM) and with 20 g of urea/kg of dietary DM (35.7 g of N/kg of dietary DM) in a split-plot design. Net splanchnic flux measurements were obtained immediately before beginning and ending a 72-h mesenteric vein infusion of L-arginine (15 mmol/h). For 3 d before and during arginine infusion, daily urine voided was measured and analyzed for N composition. Feeding urea increased PDV absorption (P < 0.01) and hepatic removal (P < 0.01) of ammonia N, accounting for 80% of increased hepatic urea N output (P < 0.01). Numerical increases in net hepatic removal of AA N could account for the remaining portion of increased hepatic urea N output. Arginine infusion increased hepatic arginine removal (P < 0.01) and hepatic urea N output (P < 0.03) and switched hepatic ornithine flux from net uptake to net output (P < 0.01), but numerical changes in net hepatic removal of ammonia and AA N could not account fully for the increase in hepatic urea N output. Increases in urine N excretion equaled quantities of N fed as urea or infused as arginine. Estimated salivary urea N excretion was not changed by either treatment. Urea cycle regulation occurs via a complex interaction of mechanisms and requires N sources other than ammonia, but the effect of increased ammonia absorption on hepatic catabolism of individual AA in the present study was not significant.

Amino Acids↗
PubMed1980

Slow ammonia release from urea: rumen and metabolism studies.

A new slow-release urea (SRU) made by coating prilled urea with a tung oil-linseed oil-talc-catalyst mixture was evaluated for ammonia-nitrogen release rate, animal acceptability, toxicity and effects on dry matter digestibility, diet intake and nitrogen retention. When added at a level equal to 1% urea in an 80% concentrate steer diet and fed twice daily, SRU gave a ruminal ammonia-nitrogen peak 1 hr postfeeding of 32 mg/dl compared to a peak from prilled urea of 53 mg/dl at 30 minutes. Bi-hourly feeding of prilled urea and SRU produced similar rumen ammonia-nitrogen levels and demonstrated that SRU was almost completely hydrolyzed in the rumen. Steers fasted for 26 hr and refed with supplements containing 10% urea from prilled urea had rumen ammonia levels of 120 ml/dl and showed muscle tremors 35 min after feeding. Rumen ammonia levels of steers fed equivalent urea from SRU remained below 35 ml/dl and exhibited no toxicity symptoms. Sheep fed ad libitum cottonseed hulls were offered a supplement containing 5% or 10% urea from urea or SRU once daily. Intake of SRU supplement was 7 and 17% greater, while cottonseed hull intakes were similar for sheep fed urea or SRU at the 5 and 10% levels. In a nitrogen balance trial, steers were fed ad libitum cottonseed hulls unsupplemented or supplemented with isonitrogenous amounts of SRU, prilled urea or soybean meal. Added nitrogen from all sources increased cottonseed hull intake. Steers fed SRU consumed more (P less than .05) cottonseed hulls than steers fed urea. Dry matter digestibility and nitrogen retention values tended to be highest for steers fed soybean meal supplement with little difference noted between prilled urea and SRU supplements.

Ammonia↗