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Results for “Tissue Distribution”

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PubMed2002

Pharmacokinetics and tissue distribution of idarubicin-loaded solid lipid nanoparticles after duodenal administration to rats.

Idarubicin-loaded solid lipid nanoparticles (IDA-SLN) and idarubicin in solution were prepared and the two formulations were administered to rats, either by the duodenal route or intravenously (iv). The aim of this research was to study whether the bioavailability of idarubicin can be improved by administering IDA-SLN duodenally to rats. Idarubicin and its main metabolite idarubicinol were determined in plasma and tissues by reversed-phase high-performance liquid chromatography. The pharmacokinetic parameters of idarubicin found after duodenal administration of the two formulations were different: area under the curve of concentration versus time (AUC) and elimination half-life were approximately 21 times and 30 times, respectively, higher after IDA-SLN administration than after the solution administration. Tissue distribution also differed: idarubicin and idarubicinol concentrations were lower in heart, lung, spleen, and kidneys after IDA-SLN administration than after solution administration. The drug and its metabolite were detected in the brain only after IDA-SLN administration, indicating that SLN were able to pass the blood-brain barrier. After iv IDA-SLN administration, the AUC of idarubicin was lower than after duodenal administration of the same formulation. Duodenal administration of IDA-SLN modifies the pharmacokinetics and tissue distribution of idarubicin. The IDA-SLN act as a prolonged release system for the drug.

Animals↗

PubMed1995

Tissue distribution, hormone regulation and evidence for a human homologue of the estrogen-inducible Xenopus laevis vitellogenin mRNA binding protein.

17 beta-estradiol induces the synthesis of massive amounts of the hepatic mRNA encoding the Xenopus laevis egg yolk precursor protein, vitellogenin. Vitellogenin mRNA exhibits a half life of approx. 500 h when 17 beta-estradiol is present, and 16 h after removal of 17 beta-estradiol from the culture medium. We recently reported that Xenopus liver contains a protein, which is induced by 17 beta-estradiol and binds with a high degree of specificity to a binding site in a segment of the 3'-untranslated region (3'-UTR) of vitellogenin mRNA implicated in 17 beta-estradiol stabilization of vitellogenin mRNA. To determine if this mRNA binding protein was specific to this system, or if it was present elsewhere, and regulated by other steroids, we examined the tissue distribution and androgen regulation of this protein. Substantial amounts of the vitellogenin 3'-UTR binding protein were found in several Xenopus tissues including testis, ovary and muscle. In the absence of hormone treatment, lung and intestine contained minimal levels of the mRNA binding protein. Testosterone administration induced the vitellogenin 3'-UTR RNA binding protein in several tissues. Additionally, we found a homologous mRNA binding protein in MCF-7, human breast cancer cells. Although the MCF-7 cell protein was not induced by 17 beta-estradiol, the MCF-7 cell mRNA binding protein appears to be closely related to the Xenopus protein since: (i) the human and Xenopus proteins elicit gel shifted bands with the same electrophoretic mobility using the vitellogenin mRNA 3'-UTR binding site; (ii) The human and Xenopus proteins exhibit similar binding specificity for the vitellogenin 3'-UTR RNA binding site; and (iii) RNA from MCF-7 cells is at least as effective as RNA from control male Xenopus liver in blocking the binding of the Xenopus and human proteins to the vitellogenin mRNA 3'-UTR binding site. Its broad tissue distribution and regulation by both 17 beta-estradiol and testosterone suggests that this mRNA binding protein may play a significant role in steroid hormone regulation of mRNA metabolism in many vertebrate cells.

Animals↗

PubMed1996

Plasma pharmacokinetics, bioavailability, and tissue distribution in CD2F1 mice of halomon, an antitumor halogenated monoterpene isolated from the red algae Portieria hornemannii.

The purpose of the present study was to define the plasma pharmacokinetics, bioavailability, and tissue distribution in mice of halomon, a halogenated monoterpene from Portieria hornemanii that is active in vitro against brain-, renal-, and colon-cancer cell lines. Halomon formulated in cremophor:ethanol:0.154 M NaCl (1:1:6, by vol.) was injected i.v. at 20, 60, 90, or 135 mg/kg into female CD2F1 mice. Doses of 135 mg/kg were also given i.p., s.c., and by enteral gavage to female CD2F1 mice and i.v. to male CD2F1 mice. Plasma halomon concentrations were measured with a gas-chromatography system using electron-capture detection. Halomon concentrations were also determined in the brains, hearts, lungs, livers, kidneys, spleens, skeletal muscles, fat, red blood cells, and, if present, testes of mice given 135 mg/kg i.v. Halomon plasma pharmacokinetics were well fit by a two-compartment, open linear model and were linear between 20 and 135 mg/kg. Population estimates of parameters describing halomon plasma pharmacokinetics in female CD2F1 mice were developed with a standard two-stage technique and also by simultaneous modeling of data from 20-, 60-, 90-, and 135-mg/kg i.v. studies in female mice. Halomon bioavailability was 45%, 47%, and 4% after i.p., s.c., and enteral dosing, respectively. Urinary excretion of the parent compound was minimal. Halomon was distributed widely to all tissues studied but was concentrated and persisted in fat. Halomon concentrations measured in the brain were comparable with concomitant concentrations detected in plasma and most other tissues. These data and models are helpful in the simulation and evaluation of conditions produced by preclinical screening and toxicology studies.

Administration, Oral↗

PubMed1990

cDNA cloning and tissue distribution of mRNAs for two proteins that are related to the band 3 Cl-/HCO3- exchanger.

Complementary DNAs encoding two proteins that are related to the Band 3 Cl-/HCO3- exchanger, designated B3RP2 and B3RP3, have been isolated from rat stomach, brain, and kidney libraries. B3RP2 is 1234 amino acids in length and has an Mr of 136,644. B3RP3 is 1227 amino acids in length and has an Mr of 135,405. B3RP2 and B3RP3 exhibit 52 and 50% amino acid identity to Band 3, respectively, and 56% identity to each other. The N-terminal cytoplasmic regions of B3RP2 and B3RP3, which span about 700 amino acids, are more extensive than that of Band 3. The C-terminal hydrophobic regions of the three proteins exhibit a high degree of amino acid identity (64-69%) and have very similar hydropathy profiles, suggesting that they have the same transmembrane organization. The tissue distribution of mRNAs encoding B3RP2, B3RP3, and the Band 3 Cl-/HCO3- exchanger were examined by Northern blot hybridization using poly(A)+ RNAs from a broad range of muscle and non-muscle tissues and from sections of the gastrointestinal tract. B3RP2 mRNAs are expressed in all tissues examined. The highest levels, which include at least three different transcripts, occur in stomach. B3RP3 mRNAs, which also consist of several different transcripts, have a more limited tissue distribution. The highest levels occur in heart, and in gastrointestinal sections the highest levels are in the forestomach. Band 3 mRNAs were observed in many tissues but high levels of expression occurred only in spleen and kidney. Five Band 3 transcripts, ranging in size from 3.6 to 4.9 kilobases, were detected, including three that are expressed in heart.

Amino Acid Sequence↗

PubMed1988

Pharmacokinetics and tissue distribution of ketanserin in rat, rabbit and dog.

The plasma kinetics and tissue distribution of ketanserin [+)-3-[2-[4-(4-fluorobenzoyl)-1-piperidinyl]ethyl]-2,4(1H,3H)- quinazolinedione, R 41 468) were studied in the rat, rabbit and dog. The studies were performed utilizing 3H- and 14C-labelled ketanserin and appropriate techniques to measure levels of radioactivity, unchanged drug and a major metabolite ketanserin-ol in plasma and tissues. Following intravenous administration to male rats and dogs (10 mg/kg), plasma levels could be described by a two-compartment model. The plasma clearance (C1) averaged 3.8 and 19.2 ml/min/kg and the volume of distribution (Vdss) 0.67 and 4.7 l/kg in male rats and in dogs, respectively. Following oral administration (10-40 mg/kg), ketanserin was rapidly and completely absorbed in all species studied. The absolute bioavailability of oral ketanserin was more than 80% in both rats and dogs. Due to the high clearance of the metabolites in rats, ketanserin was the main component of the plasma radioactivity. In dogs, the fraction of the metabolite ketanserin-ol was more pronounced than that of ketanserin. The apparent elimination half-life of ketanserin was 1.5 h in rabbits, 2-5 h in rats and 3-15 in dogs. The pharmacokinetics of ketanserin were dose-related after single and chronic intravenous and oral dosing. Distribution studies in rats after intravenous and oral administration (10 mg/kg) demonstrated an almost immediate equilibrium between plasma and tissues, resulting in slightly higher tissue than plasma concentrations in the well perfused tissues, and similar or slightly lower levels in the remaining tissues. Ketanserin was the main component of tissue radioactivity. The drug crossed the blood-brain barrier only to a slight extent, brain levels of the unchanged drug being similar to the free fraction in plasma. Ketanserin disappeared from tissues with a similar half-life to that in plasma. On repeated dosing, a small fraction of metabolites was more slowly eliminated. The excretion of the urinary and faecal metabolites after repeated dosing was very similar to that after a single dose. Placental transfer of ketanserin in the rat was limited. On average 0.3% of the maternal radioactive dose, preferentially metabolites, was recovered from the combined foetuses. In dogs orally treated with doses of up to 40 mg/kg/d for 12 months, no undue accumulation or retention of ketanserin or ketanserin-ol was found in any tissue. In lactating dogs orally dosed at 10 mg/kg, preferentially metabolites were excreted in the milk. Concentrations of ketanserin and ketanserin-ol in the milk were respectively 2 and 4 times higher than plasma levels.

Animals↗

PubMedDate not supplied

Tissue distribution and pharmacokinetics of 3-t-[methyl-14C] butyl-4-hydroxyanisole in rats.

Tissue distribution and pharmacokinetics of 3-t-[methyl-14C]butyl-4-hydroxyanisole was studied in male rats. 3-t-[methyl-14C]butyl-4-hydroxyanisole was administered by gavage at a single dose of 1.5 mmol/kg. Urine, feces, blood, and 20 major tissues were collected at 0.5, 1, 3, 6, 12, 16, 17, 18, 24, 48, 72, 168, and 240 hr after dosing and were analyzed for radioactivity. Almost all radioactivity was eliminated from rats in 48 hrs. Forty one per cent of the administered dose was recovered in urine, while feces accounted for 53%. At early time points radioactivity was mainly found in gastrointestinal tissues with concentrations remaining high up to 16-18 hr after administration indicating a slow absorption and elimination of the compound. The maximum concentration of radiolabel in kidney, liver, bladder, spleen, heart, pancreas, and brain was reached at 6 hr and remained up to 24 hr. The concentration of radioactivity in liver and kidney was approximately 10-fold higher than other tissues at the peak time of 16-18 hrs. Calculated absorption and elimination rate constants demonstrated slow uptake and clearance of label by many tissues. Covalent binding in eight representative tissues at 10 time points was also studied. Results indicate that binding increases slowly and exponentially with time reaching maximum levels at 12-24 hr in most of the tissues followed by a slow decline with time.

Animals↗

PubMedDate not supplied

Immunological evaluation of blood contamination in tissue distribution studies.

An original, simple and economical method allowing the evaluation of blood contamination in tissue distribution studies is described. This method is based on the immunochemical determination of the amount of serum albumin present in tissue samples as a quantitative measurement of blood contamination, using a single radial immunodiffusion technique according to Mancina et al. Two pharmacokinetic studies we have performed in mice for different research purposes illustrate the crucial importance of the correction for blood contamination in the exact interpretation of the tissue uptake of a given compound. We have indeed clearly demonstrated first in the development of drug-carrier complexes in targeted cancer chemotherapy and second in the study of receptor-mediated clearance of glycoproteins from the plasma that the blood contamination, if not taken into account, can greatly alter the data of uptake by target organs. Our method is thus particularly useful in in vivo pharmacokinetic studies and is moreover not restricted to one animal species.

Animals↗

PubMed1984

Replication of Borna disease virus in rats: age-dependent differences in tissue distribution.

There are age-dependent differences in the tissue distribution of Borna disease (BD) virus in rats infected intracerebrally. While in adult rats BD virus replication is restricted to neural cells, in neonatally infected rats infectious virus or viral antigens were found in the cells of most organs. The possibility that differences in the immune status between newborn and adult animals are responsible for different tissue susceptibility could be excluded.

Age Factors↗

PubMed1983

Tissue distribution of captopril, reducible captopril conjugates and S-methylcaptopril in the rat.

The tissue distribution of captopril, an antihypertensive drug possessing a free sulfhydryl group, and its sulfur-conjugated metabolites was studied in rats by gas chromatography-mass spectrometry at 15, 30 and 60 min following a single 10 mg/kg oral dose of captopril. It was found that tissue accumulation of captopril was rapid with both free and oxidized-forms already present at 15 min post-dose. A maximum concentration of captopril was achieved at 30 min in tissues studied, being substantially higher in kidney (14.2 micrograms/g), with lesser amounts occurring in liver, lung, heart, blood cells, spleen and plasma in that order. Oxidized disulfide forms of captopril were usually present in the same or slightly higher proportion than free captopril except for liver which only contained detectable disulfides at 15 min after oral dosing. S-methylcaptopril was also present at 30 min in all tissues examined with highest levels occurring in liver and kidney (1.05 micrograms/g) followed by plasma, lung, heart, spleen and blood cells.

Animals↗

PubMed1977

Tissue distribution of S-adenosylmethionine and S-adenosylhomocysteine in the rat. Effect of age, sex and methionine administration on the metabolism of S-adenosylmethionine, S-adenosylhomocysteine and polyamines.

The tissue distribution of S-adenosylmethionine, S-adenosylhomocysteine, methionine adenosyltransferase and S-adenosylhomocysteine hydrolase was explored in the rat. Also the effects of methionine administration on the accumulation of S-adenosylmethionine, S-adenosylhomocysteine and polyamines were studied in rat liver, brain and kidney. The tissue distribution of S-adenosylmethionine, S-adenosylhomocysteine, methionine adenosyltransferase and S-adenosylhomocysteine hydrolase was similar in both sexes, and was only slightly changed with age. The specific activity of S-adenosylhomocysteine hydrolase greatly exceeded that of methionine adenosyltransferase, and the concentration of S-adenosylmethionine was higher than that of S-adenosylhomocysteine in all tissues examined. However, the hepatic S-adenosylmethionine/S-adenosylhomocysteine ratio was dependent on food supply and on the age of the animal. No correlation was noticed between the activity of methionine adenosyltransferase and the concentrations of the adenosyl compounds in different tissues. Intraperitoneal administration of methionine resulted in a profound but transient increase in the hepatic concentrations of S-adenosylmethionine and S-adenosylhomocysteine. The concentration of S-adenosylmethionine was elevated also in the brain during the first 2h after methionine injection. The rise of S-adenosylmethionine concentration after methionine treatment could be diminished by simultaneous glycine administration. The results support the view that the rate-limiting factor of S-adenosylmethionine synthesis is the tissue concentration of methionine. They further suggest that glycine N-methyltransferase may have a regulatory role in the utilization of S-adenosylmethionine in the liver.

Age Factors↗

PubMed1998

Hyperinsulinaemia, regional adipose tissue distribution and left ventricular mass in normotensive, elderly, obese subjects.

Obesity is a metabolic condition, related to abnormalities of the glyco-insulinaemic metabolism, and plays a substantial role in the development of cardiovascular disease. The aim of this study was to establish a correlation among left ventricular mass, evaluated echocardiographically according to Penn Convention criteria, blood pressure, evaluated by ambulatory blood pressure monitoring, anthropometric indices for evaluation of body mass index and waist to hip ratio circumference, regional adipose tissue distribution, evaluated by ultrasound measurements of visceral adipose tissue, and insulin resistance, evaluated by hyperinsulinaemia by oral glucose tolerance test. We selected two groups of elderly male subjects well matched for age (68.5 +/- 6.4 years): 29 obese and 20 lean, with a body mass index, respectively, of 34.6 +/- 2.9 and 23.4 +/- 2.3. Statistical analysis was carried out by Student's t-test and linear regression analysis. In spite of the fact that statistical analysis showed a higher, though not statistically significant, systolic and diastolic mean blood pressure in the lean subjects, we found an increased left ventricular mass in obese subjects (P < 0.0001). The area under the insulin curve was higher in obese than in lean subjects (P < 0.0001) while the area under the glucose curve was not significantly different in the two groups. Furthermore, linear regression analysis showed that in obese subjects left ventricular mass was strictly correlated with visceral adipose tissue (r = 0.607; P < 0.0001) and hyperinsulinaemia (r = 0.615; P < 0.0001). In conclusion, our data suggest that centripetal adipose tissue distribution and hyperinsulinaemia, independent of blood pressure values, are closely correlated with left ventricular mass.

Adipose Tissue↗

PubMed2006

The kinetics and tissue distribution of protein transduction in mice.

Protein transduction domains (PTDs) offer an exciting therapeutic opportunity for the treatment of many diseases. An 11-amino acid fragment of human immunodeficiency type 1 (HIV-1) TAT-protein can transduce large, biologically active proteins into mammalian cells; recent evidence has shown an in vivo PTD for the 116 kDa beta-galactosidase protein. However, there is little information on the in vivo distribution of the TAT fusion protein to define the viability of PTDs for human studies. In this study we examined the tissue kinetics and tissue distribution of the PTD-transduced TAT fusion protein in mice. Low (100 microg) or high (500 microg) doses of TAT-beta-galactosidase fusion protein were administrated to mice through four routes (portal vein, i.v., i.p., and oral). Tissues were harvested 15 min, 1h, 6h, 10h, and 24h after treatment. Distribution of beta-galactosidase in various tissues was analysed by in situ staining, enzymatic activity assay, and Western blot analysis. Beta-galactosidase enzyme activity was observed in all tissues (liver, kidney, spleen, lung, bowel, and brain). Beta-galactosidase activity peaked at 15 min in most tissues after portal vein, i.v., and i.p. administration and at 1h after oral dosing in all tissues. Beta-galactosidase activity in the liver at 15 min after portal vein injection (67 milliunits [mU]/mg) was higher than after i.v. (9.8 mU/mg), i.p. (4.4 mU/mg), and oral (0.3 mU/mg) dosing. In situ staining and Western blot results correlated closely with beta-galactosidase enzyme activity assay. The median initial half-life for activity was 2.2h, ranging from 1.2h to 3.4h (coefficient of variation=28.9%). The bioavailability of beta-galactosidase activity after an orally administered PTD was 24%. This study details the kinetics and tissue distribution of delivering of a model TAT fusion protein into the mouse via PTD. These data allow rational selection of delivery route and schedules for therapeutic PTD and will aid the use of TAT fusion protein transduction in the development of protein therapies.

Administration, Oral↗

PubMed1994

Ca2+/calmodulin-dependent protein kinase V: tissue distribution and immunohistochemical localization in rat brain.

Polyclonal antibody against Ca2+/calmodulin-dependent protein kinase V (CaM kinase V) was prepared from guinea pigs immunized with synthetic polypeptide, based on the partial amino acid sequence of the rat brain enzyme. Immunoblot analysis of purified CaM kinase V revealed two immunoreactive bands with a molecular mass of 41 kDa and minor 40 kDa, respectively. Tissue distribution of CaM kinase V and immunohistochemical localization in rat brain were also investigated. Immunoblotting revealed the presence of immunoreactive proteins with the same molecular mass of 40 and 41 kDa, in the cerebrum, cerebellum, brain stem, pituitary gland, lung, adrenal gland, spleen, liver, colon, heart, stomach, ovary, spinal cord, and thymus. Immunohistochemistry revealed strong staining in the neuronal somata and weak staining in the nuclei. Densely stained regions included the cerebral cortex, the hippocampal formation, the caudatoputamen, the globus pallidus, the hypothalamus, the substantia nigra, the medial geniculate body, the olfactory bulb, the cerebellar cortex and the choroid plexus. CaM kinase V revealed different substrate specificity compared with CaM kinase II. These results lead to the notion that CaM kinase V may exist in 40- and 41-kDa isoforms, is widely distributed in various tissues, and may play an important role in the control of a wide variety of calcium regulated processes in the respective tissues.

Amino Acid Sequence↗

PubMed1997

Rat MDC family of proteins: sequence analysis, tissue distribution, and expression in prepubertal and adult rat testis.

Increasing number of sequence-related cysteine-rich membrane proteins containing metalloproteinase-like and disintegrin-like domains (the MDC protein family) have been identified in mammalian tissues. Here, we report the cloning and sequence analysis of cDNAs encoding several rat orthologues of this protein family, some of which are found to be expressed exclusively in the male reproductive tract, others exhibiting a broader tissue distribution. We also examine their expression in prepubertal an adult rat testis, which, in conjunction with the data on tissue distribution, form a necessary prelude to further studies aimed at establishing their individual functions.

ADAM Proteins↗

PubMed2004

Monitoring of the tissue distribution of fibroblast growth factor containing a high mannose-type sugar chain produced in mutant yeast.

Most therapeutic glycoproteins have been produced in mammalian cell lines. However, the mammalian cell culture system has various disadvantages, i.e., a high culture cost, difficulty in performing a large scale-up because of complicated handling requirements, and the risk of contamination by prion or other unknown pathogenic components through cultivation in the presence of bovine serum. There is thus a growing need for other host cells in which the recombinant glycoproteins can be produced. Recently, we successfully developed a mutant yeast strain engineered in a glycosylation system. The sugar chain produced in the mutant yeast is not immunogenic to the human immuno-surveillance system. In the present study, we selected fibroblast growth factor (FGF) as a model glycoprotein and assessed the bioactivity of FGF produced in yeast in terms of its proliferating activity and tissue distribution in mammalian cells and in the whole body. Structural changes in the sugar chains of FGFs derived from mutant yeast, as compared with those from mammalian cells, did not affect the proliferating activity remarkably. However, the tissue distribution in the mouse differed significantly; a high-mannose type sugar chain was the major determinant of the specific distribution of FGF to the kidney. The mechanism of this phenomenon is still unclear, but our observations suggest that recombinant glycoproteins derived from mutant yeasts producing high-mannose type sugar chains would be applicable for tissue-targeting therapy.

Animals↗

PubMed1991

Pharmacokinetic and tissue distribution study of oxytetracycline in rainbow trout following bolus intravenous administration.

Oxytetracycline pharmacokinetics and tissue distribution were studied in rainbow trout following bolus i.v. administration at 5 mg/kg. The mean serum (log) drug concentration data were plotted against time (linear). The decay curve was described by a three-component exponential decay function and a three-compartment model. The t1/2 of rapid distribution was 0.9 h, the t1/2 of the slow distribution was 5.9 h and the t1/2 elimination was 81.5 h. Clearance was 25.4 ml/kg/h and Vd(area) 2988 ml/kg. Regression analysis of the serum levels for the three intervals, 0.5-2.0 h, 6.0-18.0 h, and 24-96 h, indicated that the rates of decay for each interval were 0.6151 h-1, 0.0564 h-1 and 0.0088 h-1 respectively. Rates of equilibration between tissues and serum were determined. Kidney equilibrated the fastest with t1/2 to equilibration of 1.1 h for H (anterior) kidney and 1.98 h for P (posterior) kidney. The highest drug levels were found in the liver and the lowest were in the brain.

Animals↗

PubMed2005

Pharmacokinetics and tissue distribution of zidovudine in rats following intravenous administration of zidovudine myristate loaded liposomes.

Liposomes accumulating in the reticuloendothelial system (RES) appear to be a promising vehicle to improve the therapeutic index of anti-HIV drugs such as zidovudine (AZT). Since the entrapment efficiency of AZT in liposomes was found to be low and AZT leakage from liposomes is fast, zidovudine myristate (AZT-M) was synthesized as a prodrug, and AZT-M incorporated liposomes in a lyophilized form were prepared with an average diameter of 90 nm and an encapsulation efficiency of 98% after reconstitution. The pharmacokinetic profiles and tissue distribution of AZT after i.v. administration of AZT-M liposomes in rats were investigated, and the results were compared with those after i.v. administration of AZT solution. AZT levels in plasma were significantly higher following application of AZT-M liposomes compared with AZT solution, and AUC0_infinity increased from 5.0 +/- 0.7 micromol x min x ml(-1) to 8.2 +/- 1.7 micromol x min x ml(-1) accordingly. Tissue distribution studies also confirmed higher concentrations of AZT in organs of RES and brain, suggesting that AZT-M liposomes might be promising candidates for therapy of HIV infections.

Animals↗

PubMed1977

Stable and short-lived isotopes in the study of tissue distribution.

Two relatively novel techniques that are utilized in the study of tissue distribution of drugs are discussed. The first technique, GC-MS fragmentography, provides an opportunity for the identification and quantification of several compounds and internal standards, in the same analysis, at picogram to nanogram amounts. The second technique utilizes short-lived radioisotopes and external scintigraphy. This approach can continuously monitor the tissue and organ distribution of an appropriately labeled compound. It produces quantifiable results and provides an opportunity for doing several experiments on the same animal in a noninvasive manner.

Animals↗