Metabolism cages

Animals. Male Spartan strain Sprague Dawley rats weighing 165-210 grams were used. The rats were acclimated to the environment of the metabolism cages five days before dosage. Food and water were provided ad libitum throughout the experiment. 

Due to the difficulty in obtaining sufficient volumes of urine in dogs over short collection periods, urine is usually collected overnight (approximately a 16- to 17-h period) in metabolism cages. It is recommended that a sample for urinalysis be taken early in the collection process, and that all samples be collected in fight-resistant containers to help avoid problems such as dissolution of urine casts, increased bacterial activity, and breakdown of bilirubin with exposure of the sample to fight. 

For urine collection, rat metabolism cages work well for short-term or overnight collection. Care needs to be taken to avoid contamination of the urine with feces. 

Urine collection in nonhuman primates can be measured using either a metabolism cage or a collection pan (equipped with a screen to catch the feces), which is inserted under the floor grid of the home cage. The advantage of the latter system is... 

Individual metabolism cages are recommended for collecting urine and feces in oral dosing studies. Excreta should be collected for at least 5 elimination half-lives of the test substance. When urine concentrations will be used to determine elimination rates, sampling times should be less than one elimination half-life (taken directly from the bladder in IV studies) otherwise, samples should be taken at equal time intervals. 

The required data generally are obtained by administering a measured dose of the candidate compound -- often isotopically labelled -- to the rat or mouse either by injection or per os. The animal is housed in a glass metabolism "cage" where it receives food, water, and clean air, and its urine, feces, and respired gases are collected and examined for the parent chemical and its metabolites. Eventual postmortem tissue analysis and calculation of material balance complete the measurements necessary to satisfy the above purposes of metabolism and pharmacokinetic experiments. While in vitro biochemical studies are important adjuncts, it is also apparent that only experiments with intact, healthy, living animals will suffice to meet EPA criteria. 

Renal Water intake, food intake, body weight, urine volume, urinary excretion of Na, K, Cl Metabolism cage Rat ... 

Gastrointestinal Feces weight, aspect Clinical observation or metabolism cage Rat, dog ... 

Metabolic Transit of Peptide Bound Heat-Treated and Oxidized T ryptophan. The radioactive glycyl-L- (3H) -tryptophylglycine was synthesized by the method proposed by Zimmerman et al. (134) (N-hydroxysuccinimide -j- dicyclohexylcarbodiimide) and treated under the following conditions (a) oxidation by 0.2M hydrogen peroxide at pH 7 for 30 min at 50°C and (b) heat treatment (130°C for 3 h at pH 7) (137). The untreated, oxidized and heat-treated radioactive peptides were given to rats accustomed to eating two meals a day in metabolic cages to collect the urines and feces. 

Collect urine overnight by placing mice in metabolic cages, prior to sacrifice. During this collection, allow mice free access to water but not food. 

Urine protein excretion should be measured on timed overnight specimens collected at intervals from 3 d to 3 wk from individual mice in metabolism cages and is assayed by the sulphosalicylic method. 

Klatt et al. (1975) described a method of collecting urine excreted by large animals. On the basis of urine funnels used in rats, an appropriate larger metabolism cage made out of transparent, rigid polyvinyl chloride was used. The cage was improved by a built-in sieve cone which assured good separation of urine and feces. A device to measure and record the time and amount of voided urine was attached. Urine was collected in a vessel with a hose connection from the bottom to... 

Animals are placed in appropriately-sized metabolism cages for an appropriate period of time to allow collection of an adequate volume of urine (for large animals only a few hours may be needed for rodents, 12-24 hours might be required). To preserve the quality of the urine specimens, the collection vial must have a small neck (to prevent evaporation of water) and it should be surrounded by wet ice or frozen cold packs to ensure the urine is maintained at 4 °C for the duration of the collection period (Emeigh Hart and Kinter 2005). At the end of the collection period a blood sample is obtained under appropriate anesthesia (note the use of C02 will falsely elevate plasma potassium levels and render the method inaccurate) for determination of electrolyte and creatinine levels. 

Fasted Cebus monkeys (Cebus albifrons) of either sex weighing 3.0 to 5.0 kg are used. On the morning of the experiment, the animals receive 20 ml/kg drinking water by gavage, followed by oral administration of the test compound. Allopurinol and probenecid are used as control compounds. Control animals receive water only. The animals are placed in individual metabolism cages and the spontaneously voided urine is collected after 2, 6, and 24 h. After 2 and 6 h, an additional 4 ml/kg water is given by gavage. From a cubital vein blood is withdrawn prior to the experiment and 2, 6 and 24 h after application. 

The urine creatinine concentration should be used to normalize the quantity of any analyte of interest, as this will correct for incomplete urine collection or urine dilution that may have resulted from drinking water spillage within the metabolism cages (Haas et al. 1997). The quantity of creatinine in a spot urine sample serves as an accurate index of the 24 hour urine output in most species. 

The animals are housed in individual metabolic cages. For bile collection, they are attached to long swivelled PE-cannulas (0.75 x 1.45 mm). A stainless steel coil is used to protect the rats from gnawing on the tubing. For continuous collection of bile, the cannula can be connected to a fraction collector. 

Bowden et al. (1988) used metabolism cages equipped with automated feeding monitors. Food was provided as 45 mg pellets which were singly delivered to a feeding trough. A photodetector sensed the removal of the pellet, and the number of pellets delivered over a specified time interval was recorded. 

Excretion of corticosterone, in the urine of at least 6 rats but control and treatment groups (pooled urine of 2 rats per metabolism cage). 

Modifications of the method are the duration of treatment (not less than seven days), timing of treatment injections (conventional regimen in the morning, or injections late in the evening shortly before starting the urine collection period after transfers to metabolism cages). 

The urine is collected according to the preinstructed collection intervals directly from the urine collection container of the metabolism cage. The samples are weight and directly after stirring and homogenizing the urine, aliquots are taken for radioanalysis. The remainder is bottled and frozen for additional investigations planned (metabolite profile and identification and/or bioanalysis). 

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