Urine collecting apparatus

An experiment has been done to confirm the participation of renal route in PCP excretion by goldfish, using a urine collecting apparatus shown in Figure 1. 

After 24-h exposure to 0.1 ppm PCP, goldfish(av. 70 g) were transferred into the urine collecting apparatus and a catheter inserted Into the urinary bladder from the urogenital cavity. Approximately 13 ml of urine was collected from each fish for 24 h. The urine collected from 14 fish was pooled and used for the determination of PCP. 

Any physiological fluid such as plasma, saliva, urine, or breath water vapor can be collected for the determination of fractional turnover rates of and and JVh and Nq. In most human studies, urine is the preferred sample because it is noninvasive and the easiest to collect. In infants, urine can be collected using cotton balls (Wong et al, 1993a). The urine absorbed by the cotton balls can be expressed with a plastic syringe into an appropriate sample vial. If the samples are not processed immediately for isotope ratio measurements, they should be stored at —20 C until ready for analysis. The sample collection apparatus must be free of moisture in order to avoid dilution of the samples, particularly when only small quantities are available. 

Percutaneous absorption can be determined by applying a known amount of chemical to a specified surface area and then measuring the level of the chemical in the urine and/or feces. To correct for incomplete excretion of the material in urine/feces levels are measured following parenteral administration of the chemical. Radioactive-labeled chemicals, usually carbon 14 or tritium, are widely used for analytic convenience. Ingestion of the test material by the animal must be prevented, and this may require restraint of the animal or design of specialized protective apparatus for the site of application. Because urine and feces are collected for analysis, specialized cages are also required. 

To begin the experiment, each female (18—25 g) was removed, injected with tritiated PGp2 (Dupont NEN, Boston, MA 3.6 pCi or -3,600,000 cpm, 20 pg PGF2 ), briefly dipped into another bucket of water to rinse off excess radiation, and returned to the experimental apparatus. The pump withdrew water at 5 ml/10 s, and 5 ml samples were collected every minute from 15-45 min after returning the female to the apparatus. We chose 1 min intervals because it was the fastest rate at which we could sample reliably and because Experiment 1 demonstrated that goldfish typically urinate less than once per minute. Water samples were mixed with scintillation fluid in a 1 3 ratio, and radiation levels of samples were measured in a scintillation counter. Each sample was counted three times, and the average for each sample was used to calculate (see below) whether or not an increase in radiation was attributable to urinary release. 

Figure 52. Apparatus for collecting samples from anesthetized fish. Distilled or tap water was pumped over the gills of the experimental fish in the chamber, flowed out the side arm into the two colunms, each containing 10 g ion-exchange resin (IRA 400). The cannula delivered urine into a 10-ml graduated cylinder. To secure the animals in position, damp cotton was tucked in around the tail of the fish. From Hunn and Fromm (1964).

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