Non-cannulated Rats Research Articles

Generation of High-Quality Pharmacokinetic Data From Parallel Tail Vein Dosing And Bleeding in Non-cannulated Rats.

It is common practice to use cannulated rats forpharmacokinetic (PK)in-life studies as it yields high quality PK parameter estimation. While offering many benefits, cannulation requires surgery, post-surgical care, and cannula maintenance. As an alternative approach, the strategy of dosing and bleeding rats via the tail vein in a single experiment is technically feasible and theoretically offers many benefits. Unfortunately, however, as reported by FTseet al. in 1984 (J Pharm Sci 73: https://doi.org/10.1002/jps.2600731128), parallel tail dosing and bleeding is scientifically flawed and yields inaccurate estimation of PK parameters following intravenous administration. The underlying causality of poor data quality has not been addressed in over 35 years. To overcome the technical flaws associated with parallel tail dosing and bleeding, we have developed a Tail-Dose-Bleed (TDB) method as a substitute for use of cannulated rats. Specifically, the method introduces a flush procedure after dosing,uses separate tail veins for dosing and bleeding, andadjusts dosing and sampling to the proximal and distal portions of the tail, respectively. To demonstrate the proof of principle for this TDB technique, several cassette dosing studieswere conducted.The performance of the TDB technique is comparedinboth stand alone and animal crossover studies employing conventional jugular/femoral bleeding and dosing. The poor data via tail dosing and bleeding previously described by Tse etal. are also recapitulated using their described approach. To ensure broad applicability of the TDB technique, data were generated utilizing compoundsof diversephysical chemical properties manifesting arange of clearance and/or volume of distribution characteristics.These datademonstrate that the TDB approach yields comparable PK profiles and parametersas compared to conventional femoral dosing / jugular bleeding.Using this newly described TDBprocedure, we demonstrate the ability to overcome documented data qualityissues when dosing and bleeding via the tail. The TDB technique has numerous operational advantages of reduced study turnaround time and improved cost effectiveness, but most importantly, addresses key animal welfare concerns relevant to institutional animal care and use committees (IACUC). The notable advantage here is reduced animal stress and discomfort by eliminating the need for surgery and recovery. And by consequence, allows for animals to be group housed and re-used without concern for loss of cannula patency. The tail dose and bleed methodissimple and appears readily transferable to other laboratories.

Rate-Determining and Rate-Limiting Steps in the Clearance and Excretion of a Potent and Selective p21-Activated Kinase Inhibitor: A Case Study of Rapid Hepatic Uptake and Slow Elimination in Rat.

Background: Significant under-prediction of in vivo clearance in rat was observed for a potent p21-activated kinase (PAK1) inhibitor, GNE1.Objective: Rate-determining (rapid uptake) and rate-limiting (slow excretion) steps in systemic clearance and elimination of GNE1, respectively, were evaluated to better understand the cause of the in vitro-in vivo (IVIV) disconnect.Methods: A series of in vivo, ex vivo, and in vitro experiments were carried out: 1) the role of organic cation transporters (Oct or Slc22a) was investigated in transporter knock-out and wild-type animals with or without 1-aminobenzotriazole (ABT) pretreatment; 2) the concentration-dependent hepatic extraction ratio was determined in isolated perfused rat liver; and 3) excreta were collected from both bile duct cannulated and non-cannulated rats after intravenous injection.Results: After intravenous dosing, the rate-determining step in clearance was found to be mediated by the active uptake transporter, Oct1. In cannulated rats, biliary and renal clearance of GNE1 accounted for only approximately 14 and 16% of the total clearance, respectively. N-acetylation, an important metabolic pathway, accounted for only about 10% of the total dose. In non-cannulated rats, the majority of the dose was recovered in feces as unchanged parent (up to 91%) overnight following intravenous administration.Conclusion: Because the clearance of GNE1 is mediated through uptake transporters rather than metabolism, the extrahepatic expression of Oct1 in kidney and intestine in rat likely plays an important role in the IVIV disconnect in hepatic clearance prediction. The slow process of intestinal secretion is the rate-limiting step for in vivo clearance of GNE1.

Effects of Selective iNOS Inhibitor on Spatial Memory in Recovered and Non-Recovered Ketamine Induced Anesthesia.

Nitric oxide (NO) is thought to be involved in spatial learning and memory in several brain areas such as hippocampus. This study examined the effects of post-training intrahippocampal microinjections of 1400W as a selective iNOS inhibitor on spatial memory, in anesthetized and non-anesthetized situations in rats. In the present work, 4-day training trials of animals were conducted. Spatial memory was tested 48 hours after the drug infusions. For microinjection of 1400W into CA1 region of the hippocampus in conscious animals, guide cannula was implanted into the CA1 area and 1400W was infused after recovery from surgical anesthesia. In anesthetized animals, 1400W was microinjected directly into CA1 region by Hamilton syringe during anesthesia. After completion of training, 1400W (10, 50 and 100 μM/side) were microinjected bilaterally (1 μL/side) and testing trials were performed 48 h after drug infusions in both groups of cannulated and non-cannulated rats. Significant reduction was observed in escape latency and traveled distance in animals that received 1400W (100 μM/side, *p < 0.05) via cannula after recovery in comparison with control group. Also, microinjection of 1400W (100 μM/side) in post recovery phase caused a significant (***p < 0.001) reduction in time and distance of finding the hidden platform in comparison with anesthetized situation. These findings suggest that 1400W has a significant improvement on spatial memory and memory enhancement induced by iNOS inhibitor can be affected by anesthesia in a period of time.

Comparing levels of biochemical markers in CSF from cannulated and non-cannulated rats

Cerebrospinal fluid (CSF) is commonly used for assessing biomarkers of drug efficacy or disease progression in the central nervous system. Studies of CSF from pre-clinical species can characterize biomarkers for use in clinical trials. However, obtaining CSF from pre-clinical species, particularly rodents, can be challenging due to small body sizes, and consequently, low volumes of CSF. Surgical cannulation of rats is commonly used to allow for CSF withdrawal from the cisterna magna. However, cannulae do not remain patent over multiple days, making chronic studies on the same rats difficult. Moreover, CSF biomarkers may be affected by cannulation. Thus cannulation may contribute confounding factors to the understanding of CSF biomarkers. To determine the potential impact on biomarkers, CSF was analyzed from cannulated rats, surgically implanted with catheters as well as from non-cannulated rats. Brain protein biomarkers (αII-spectrin SBDP150 and total tau) and albumin, were measured in the CSF using ELISA assays. Overall, cannulated rat CSF had elevated levels of the biomarkers examined compared to non-cannulated rat CSF. Additionally, the variation in biomarker levels observed among CSF from cannulated rats was greater than that observed for non-cannulated rat CSF. These results demonstrate that in some cases, biomarker assessment using CSF from cannulated rats may differ from that of non-cannulated animals and may contribute confounding factors to biomarker measurements and assay development for clinical use.

Affects of cannulation on CSF biomarker composition and consistency in Sprague-Dawley rats

Cerebral spinal fluid (CSF) is commonly used for assessing biomarkers of drug efficacy and/or disease progression in the central nervous system. Studies of CSF from pre-clinical species can identify and characterize biomarkers for use in clinical trials. However, obtaining CSF from pre-clinical species, particularly rodents can be challenging due to small body sizes and the consequent low volumes of CSF. Surgical cannulation of rats is commonly used to allow for CSF withdrawal from the cisterna magna. However, CSF biomarkers may be affected by cannulation, thus introducing potential problems in translating the biomarkers to the clinic. Cannulated and non-cannulated rats were purchased from Charles River Labs. The cannulated rats were surgically implanted with catheters accessing the cisterna magna. CSF was collected from the non-cannulated rats by inserting a 25 or 27 gauge butterfly needle into the cisterna magna. Daily CSF withdrawals were attempted from individual rats using each model type. Using ELISA, protein biomarkers and albumin and other biomarkers were measured in the CSF from dozens of rats representing cannulated or non-cannulated methods. CSF from cannulated rats differs from that of non-cannulated rats in its protein composition. Of the biomarkers examined, including albumin, cannulated rat CSF biomarker levels were higher relative to non-cannulated rats. The variation in biomarker levels observed in CSF from cannulated rats was also greater than that observed from non-cannulated rats. In addition, multiple CSF collections from the same rats were more successful when the non-cannulated rats were used. Intracisternal-cannulation of rats may affect the biomarker composition of the CSF. Thus biomarker assessment using CSF from cannulated rats may not provide data representative of naive animals and may contribute confounding factors to biomarker identification and development for clinical use. Studies that utilize non-cannulated rats may provide data that is more biologically relevant than those conducted on cannulated rats, and ultimately may provide critical data on biomarkers that can be more readily translated to the clinic.

Effects of Selective iNOS Inhibitor on Spatial Memory in Recovered and Non-recovered Ketamine Induced-anesthesia in Wistar Rats.

Nitric oxide (NO) is thought to be involved in spatial learning and memory in several brain areas such as hippocampus. This study examined the effects of post-training intrahippocampal microinjections of 1400W as a selective inducible nitric oxide synthase (iNOS) inhibitor on spatial memory, in both anesthetized and non-anesthetized situations in rats. In the present work, 4-day training trials of animals were conducted. Spatial memory was tested 48 h after the drug infusions. For microinjection of 1400W into CA1 region of the hippocampus in conscious animals, guide cannula was implanted into the CA1 area and 1400W was infused after recovery from surgical anesthesia. In anesthetized animals, 1400W was microinjected directly into CA1 region by Hamilton syringe during anesthesia. After completion of training, 1400W (10, 50 and 100 μM/side) were microinjected bilaterally (1 μL/side) and testing trials were performed 48 h after drug infusions in both groups of cannulated and non-cannulated rats. Significant reduction was observed in escape latency and traveled distance in animals that received 1400W (100 μM/side, * P < 0.05) via cannula after recovery in comparison with control group. Moreover, microinjection of 1400W (100 μM/side) in post recovery phase also caused a significant (*** P < 0.001) reduction in time and distance of finding the hidden platform in comparison with anesthetized situation. These results suggest that 1400W has a significant improvement on spatial memory, and memory enhancement induced by iNOS inhibitor can be affected by anesthesia in a period of time.

Partial contribution of biliary metabolites to nephrotoxicity, renal content and excretion of [14C]hexachloro-1,3-butadiene in rats.

Male Sprague Dawley rats with cannulated bile duct (BDC rats) received 100 or 200 mg kg-1 labelled hexachloro-1,3-butadiene ([14C]HCBD) by gavage 1 h (BDC1 rats) or 24 h (BDC24 rats) after surgical cannula implantation. Twenty-four hours after treatment with HCBD, rats were examined histochemically and biochemically for kidney damage. Urine, faeces, liver and kidney radioactivities were also measured in 24-h samples. Results were compared with those obtained from non-cannulated (NC) rats. Bile-duct cannulation did not completely protect against HCBD-induced kidney damage. The 24-h [14C] urinary excretion and tissue content was 30-50% lower in BDC rats compared to NC rats and correlated well with the toxicity findings. BDC1 rats appeared to be much more resistant to HCBD treatment than BDC24 rats. Since faecal [14C] radioactivity extractable by diethyl ether at neutral pH in BDC1 rats was twice that measured in BDC24 rats, the greater resistance was attributed to a higher deficiency in the gastrointestinal absorption of unchanged HCBD. The present results reveal that the biliary metabolites of HCBD are not solely responsible for kidney toxicity as previously assumed. They suggest a sinusoidal efflux of the HCBD conjugates from the liver.

Biliary excretion of hexachloro‐1,3‐butadiene and its relevance to tissue uptake and renal excretion in male rats

Renal, biliary, pulmonary and faecal excretion experiments were carried out with labelled hexachloro-1,3-butadiene [( 14C]HCBD) in male Sprague-Dawley rats, given orally (p.o.) and intravenously (i.v.) in doses of 1 and 100 mg kg-1 as a solution in polyethylene glycol. The radioactivity excreted over 72 h was determined in rats fitted with exteriorized biliary cannulae and in rats whose bile ducts remained fully functional, respectively. In addition, bile duct-duodenum cannula-linked rats, of which the donor was given 100 mg kg-1 [14C]HCBD orally and the recipient had also a bile fistula, were examined within 30 h for radioactivity in the excreta, the kidney, the liver and the plasma. In non-cannulated rats, fractional urinary excretion decreased when the dosage increased and amounted to 23% and 8.6% after i.v. injection or 18.5% and 8.9% after p.o. administration of 1 and 100 mg kg-1, respectively. Pulmonary excretion of radioactivity was less than 9% and was not affected by the increase in dosage. In bile duct-cannulated rats, fractional urinary excretions were similar irrespective of the dose and the route of administration and amounted to ca. 7.5% of the dose. Decrease in fractional biliary excretion occurred with increase in dosage (88.7% vs 72%) after i.v. injection and (66.8% vs 58%) after gavage. In cannulated rats, faecal excretion was less than 0.5% after i.v. injection and accounted for 3% and 16% of the dose after p.o. administration of 1 and 100 mg kg-1, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes of experimental allergic encephalomyelitis by methionine-enkephalin injected into lateral ventricles of the rat brain

Our previous investigations have shown that the opioid peptide methionine-enkephalin (Met-Enk) modulates in vivo a variety of humoral and cell-mediated immune performances. In this study, rats bearing polyethylene cannulae permanently inserted into the lateral ventricles of the brain were used. Experimental allergic encephalomyelitis (EAE) was induced with guinea pig spinal cord in complete Freund's adjuvant injected into the left hind foot pad. The following groups of cannulated rats were tested: nontreated with Met-Enk or saline, intracerebroventricularly (i.c.v.) injected with saline, and i.c.v. treated with low (1 microgram/kg) dose of Met-Enk and high (1 mg/kg) dose of Met-Enk. Intact noncannulated rats sensitized for EAE served as an additional control. The results showed that i.c.v. treatment with 1 microgram/kg of Met-Enk significantly increased the incidence and severity of EAE. In contrast, injections of 1 mg/kg of Met-Enk produced a moderate decline of clinical EAE, but marked diminution of inflammatory lesions in the brain. Interestingly, histopathology of EAE was more pronounced in control rats treated i.c.v. with saline. On the other hand, control cannulated rats noninjected with saline exhibited a striking decrease of neurological and histopathological signs of the disease, thus indicating a suppressive effect of stress (surgical procedure) on EAE. In conclusion, the present study showing the central effect of Met-Enk on EAE when peptide was applied in the cerebral cavity, and earlier studies which revealed the peripheral effect on EAE when Met-Enk was administered intraperitoneally, suggests that Met-Enk exerts its immunomodulatory action both centrally and peripherally.

Vasopressin responses to hypoxia in conscious rats: interaction with water restriction

The purpose of this study was to determine the effect of water restriction on the vasopressin response to hypoxia in conscious Long-Evans rats. Rats were prepared with chronic indwelling femoral artery and vein catheters 1 week before experimentation. At 24 h before the first blood sample, the supply of drinking water was maintained ad libitum (water replete) or removed (water deplete). At 24 h, a control blood sample was taken and then normoxia (21% O2) was maintained or hypoxia (10% O2) induced. Additional blood samples were taken at 1, 18 and 24 h. All blood samples (2.5 ml) were simultaneously replaced with donor blood to maintain isovolaemia. Hypoxia led to a very small and transient increase in vasopressin in the water-replete rats. The combination of hypoxia and water restriction led to a greatly augmented vasopressin response at 1 h (60 +/- 16 pmol/l); this response was also not sustained. Additional non-cannulated rats were exposed to 24 h of normoxia or hypoxia with or without water available ad libitum and posterior pituitaries were collected after decapitation for measurement of vasopressin content. Water restriction, hypoxia and water restriction plus hypoxia all led to decreased pituitary vasopressin content. We conclude that the vasopressin response to hypoxia in conscious rats is small and transient, and that concomitant water restriction augments the vasopressin response to acute but not chronic hypoxia.

Paraquat pharmacokinetics using a subcutaneous toxic low dose in the rat

The pharmacokinetics of paraquat were examined at a dose which produced lung disease but avoided renal damage. Following single sc injections of 14CH 3 -paraquat (72 μmol/kg) in male Sprague-Dawley rats, blood was sampled via indwelling jugular cannulas. Noncannulated rats were exsanguinated by cardiac puncture during a 7-day test period. Blood, liver, kidney, lung, brain, heart, spleen, gi tract, injection site, adrenals, body, urine, and feces were analyzed for total radioactivity. Histology of lung after 7 days revealed (+1) paraquat lung disease. No evidence of renal damage was observed. Paraquat was rapidly absorbed. Peak blood concentrations of 58 nmol/ml were measured at 20 min. Peak lung and kidney paraquat concentrations at 40 min were 65 and 359 nmol/g, respectively. Paraquat pharmacokinetics (NONLIN) were best described by a two-compartment open model; the mean biological half-life was 40.9 hr. Eighty-five percent of the dose was eliminated in urine by 7 days. The body contained 79% of the remaining radioactivity. The residual radioactivity is associated with prolonged paraquat excretion and, perhaps, progressive lung disease.

Paraquat Pharmacokinetics Using a Subcutaneous Toxic Low Dose in the Rat

Paraquat Pharmacokinetics Using a Subcutaneous Toxic Low Dose in the Rat. M. S. DEY, R. G. BREEZE, W. L. HAYTON, A. H. KARARA, AND R. I. KRIEGER. 1990. Fundam. Appl. Toxicol. 14, 208–216. The pharmacokinetics of paraquat were examined at a dose which produced lung disease but avoided renal damage. Following single sc injections of l4CH3-paraquat (72 μmol/kg) in male Sprague-Dawley rats, blood was sampled via indwelling jugular cannulas. Noncannulated rats were exsanguinated by cardiac puncture during a 7-day test period. Blood, liver, kidney, lung, brain, heart, spleen, gi tract, injection site, adrenals, body, urine, and feces were analyzed for total radioactivity. Histology of lung after 7 days revealed (+1) paraquat lung disease. No evidence of renal damage was observed. Paraquat was rapidly absorbed. Peak blood concentrations of 58 nmol/ml were measured at 20 min. Peak lung and kidney paraquat concentrations at 40 min were 65 and 359 nmol/g, respectively. Paraquat pharmacokinetics (NONLIN) were best described by a two-compartment open model; the mean biological half-life was 40.9 hr. Eighty-five percent of the dose was eliminated in urine by 7 days. The body contained 79% of the remaining radioactivity. The residual radioactivity is associated with prolonged paraquat excretion and, perhaps, progressive lung disease.

Blockade of only spinal α1 adrenoceptors is insufficient to attenuate DDT-induced alterations in motor function

Male Fischer 344N rats were chronically implanted with an intrathecal cannula and gavaged with p,p′-DDT (1,1,1-trichloro-2,2-bis[ p-chlorophenyl]ethane; 30 or 45 mg/kg) or corn oil. Seven hours later, subjects were intrathecally infused with vehicle, 15, 30, 60, or 120 μg of prazosin (an α 1-adrenergic antagonist). Spectral analysis of bodily movements was performed 7.5, 8, and 10 hr after DDT administration. In control rats, 15 μg of prazosin reduced the spectral profiles of spontaneous movements. A 30-μg dose produced motor impairments, without significantly changing the spectral profiles. Tremulous movements induced by DDT were unaffected by 15 or 30 μg, whereas 60 or 120 μg of intrathecal prazosin significantly reduced the spectral profiles of rats pretreated with 45 mg/kg of DDT. Other subjects were administered vehicle or DDT (45 mg/kg), intrathecally infused with 15 or 60 μg of prazosin (7 hr), and sacrificed (7.5 hr). Noncannulated rats were gavaged with 60 mg/kg of DDT, injected subcutaneously (sc) with 0.5 mg/kg of prazosin (5.5 hr), and sacrificed (8 hr). Cortical and spinal tissues were used in ex vivo binding assays utilizing [ 3H]prazosin. Fifteen or sixty micrograms of intrathecal prazosin occupied similar percentages of spinal [ 3H]prazosin binding sites, but produced a dose-related increase in cortical prazosin equivalents. Sixty micrograms of intrathecal or 0.5 mg/kg of sc prazosin resulted in similar concentrations of cortical prazosin equivalents. Together, these data indicate that while intrathecal prazosin will attenuate DDT-induced motor dysfunction, this effect requires blockade of α 1 adrenoceptors in regions other than solely the spinal cord.

Role of Alpha-Adrenergic Mechanism in Effects of Morphine on the Hypothalamo-Pituitary-Adrenocortical and Cardiovascular Systems in the Rat

The role of alpha-adrenergic mechanism in the acute effects of morphine in the hypothalamo-pituitary-adrenocortical (HPA) and cardiovascular (CV) systems, and the interrelationship between the HPA and CV responses to alpha-adrenoceptor antagonists and/or morphine were studied by peripheral administration of prazosin, a selective alpha 1-adrenoceptor antagonist, and yohimbine, a selective alpha 2-adrenoceptor antagonist, in conscious, unstressed or ether-stressed rats. The test substances were administered intravenously or intraperitoneally in chronically cannulated or noncannulated rats. In the i.v. experiment, morphine (1 mg/100 g BW) rapidly induced a pronounced bradycardia and a short-lasting fall in blood pressure (BP), followed by a rise in BP, and increased plasma corticosterone concentration. Prazosin (0.5 mg/kg BW) induced a rapid fall in BP and tachycardia, and increased plasma corticosterone concentration. Pretreatment with prazosin did not block the effect of morphine on the CV system, but abolished the morphine-induced increment in plasma corticosterone concentration. Yohimbine (0.5 mg/kg BW) induced a rapid and a subsequent slowly developing rise in BP and tachycardia, and increased plasma corticosterone concentration. Pretreatment with yohimbine did not block the effect of morphine on the CV system nor alter the stimulatory effect of morphine on the secretion of corticosterone. In the intraperitoneal experiment, morphine (2 mg/100 g BW) stimulated the secretion of adrenocorticotropic hormone (ACTH) and corticosterone and prazosin (1 mg/kg BW) stimulated the secretion of corticosterone, but pretreatment with prazosin reduced the morphine-induced increment in plasma corticosterone concentration in unstressed rats. In stressed rats, morphine reduced the stress-induced increment in plasma ACTH and corticosterone concentrations and prazosin also reduced the stress-induced increment in plasma corticosterone concentration. Pretreatment with prazosin did not alter the inhibitory effect of morphine...

CCK inhibits real and sham feeding in gastric vagotomized rats

We tested both sham feeding and real feeding in gastric vagotomized rats equipped with chronic gastric cannulas, either without pretest food deprivation or after 18 hr food deprivation. In each condition, 0.3–4 μg/kg CCK inhibited food intake similarly in control and vagotomized rats. Behavioral observations indicated the presence of normal postprandial satiety after CCK. We then tested real feeding in noncannulated rats after either total abdominal vagotomy, gastric vagotomy, or control operation. Doses of 0.5–4 μg/kg CCK had no effect on food intake after total vagotomy, but again inhibited feeding with equal potency in gastric vagotomized and control rats. The inhibitory effect of 6 μg/kg CCK was attenuated but not blocked by total vagotomy. Finally, we tested rats with gastric cannulas after gastric plus celiac vagotomy. CCK also inhibited both real and sham feeding after this lesion. These data confirm previous findings that abdominal vagal fibers mediate the satiety effect of moderate intraperitoneal doses of CCK, but fail to support the hypothesis that gastric branch fibers are the necessary vagal contribution.

Metabolism and excretion of butein, 2',3,4-trihydroxychalcone, 3-O-methylbutein, 4-O-methylbutein and 2',4',4-trihydroxychalcone in the rat.

Butein (2',3,4,4'-tetrahydroxychalcone) and 2',3,4-trihydroxychalcone, following administration to bile-duct-cannulated rats, gave rise to the corresponding 3-O-methyl ethers which were excreted in conjugated forms in bile and urine. After parenteral and oral administration of [14C]butein, 53% and 20% of the dose, respectively, was excreted in bile in 24h. After oral administration of [14C]butein, 4-O-methylbutein, or 2',4',4-trihydroxychalcone to non-cannulated rats, 51%, 58% and 40% dose, respectively, was excreted in faeces, and 39%, 37% and 56%, respectively, in urine. Intraperitoneal administration of butein to non-cannulated rats led to excretion of 41% dose in urine and 56% in faeces. 3-O-Methylbutein and 4-O-methylbutein were demethylated in vivo and on incubation with rat-intestinal microflora in vitro, whilst 2',4-dihydroxy-3-methoxychalcone and 2',3-dihydroxy-4-methoxychalcone were not demethylated in vivo or in vitro. Following parenteral and oral administration of 4-O-methylbutein to bile-duct-cannulated rats, 91% and 21% dose, respectively, was excreted in the bile in 24h. After parenteral or oral administration of 2',4',4-trihydroxychalcone to cannulated rats, approx. 100% and 45% dose, respectively, was excreted in the bile in 24h. Trace amounts of 2',4',4-trihydroxychalcone were hydroxylated to give butein.

Action of DTPA on Hepatic Plutonium: I. Quantitation of the DTPA-Induced Biliary Excretion of Plutonium in the Rat

Rats received an intravenous injection of 0.1 μCi of ${}^{239}{\rm Pu}\text{-citrate}$ (approx 0.5 μCi/kg). At 24 hr after Pu injection, the bile ducts were cannulated and diethylenetriaminepentaacetic acid (DTPA, 0.25 mmole/kg) was injected intravenously. The amount of Pu appearing in the bile during the first 24 hr after DTPA injection was determined. In addition, the decrease in Pu content of the liver 24 hr after DTPA administration was measured in both bile duct-cannulated and noncannulated rats and compared to the amount of Pu appearing in the bile. Bile collected from control rats receiving saline instead of DTPA contained 0.40 ± 0.08 nCi of Pu (mean ± SE, n = 3), while bile collected for 24 hr after DTPA administration contained 7.2 ± 0.4 nCi Pu (mean ± SE, n = 6). Thus, DTPA administration brought about a striking increase in biliary Pu excretion. The mean decrease in liver Pu content 24 hr after DTPA administration to rats whose bile ducts were not cannulated was 7.4 ± 1.4 n...

Metabolism of the hydroxyethylrutosides. Biliary and urinary excretion of 3',4',5-(hydroxyethyl- 14 C), 7-tetra-O-( -hydroxyethyl)-rutoside in rats and monkeys after parenteral administration.

1. 3′,4′,5-[Hydroxyethyl-*C],7-tetra-O-(β-hydroxyethyl)rutosideis rapidly excreted unchanged, in both urine (42–71% dose in 24 h) and in bile (15–39% in 24 h) following parenteral administration of a single dose (3–8 mg/kg body wt.). Biliary excretion is max. within the first 3 h and virtually complete by 24 h at this dosage.2. Excretion of the glycoside in the urine of non-cannulated rats amounted to 32–70% dose in 24 h. Between 14–23% of the parenterally administered dose was extracted from the faeces of non-cannulated rats, mostly as the [14C] aglycone.3. Following intravenous administration of the glycoside to non-cannulated rhesus monkeys 50–58% dose was excreted in the urine and 19–27% was found to be excreted into the gall bladder.