Purification of monoclonal antibody to clenbuterol and its biology identity / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To identify the self-preparation monoclonal antibody which target to clenbuterol, and set up the standard curve to clenbuterol (CL) detection.</p><p><b>METHODS</b>The affinity constants and activity of the monoclonal antibody which target to CL were determined by ELISA. ELISA was also used to confirm whether the monoclonal antibody had any across-reaction with BSA and CL analogues. The rat ascites which contains the monoclonal antibody target to CL was purified by (NH4)2SO4 salt-out method and further by affinity column. At last, the CL detection standard curve which based on indirect competition ELISA was established.</p><p><b>RESULTS</b>The ELISA experiment showed that the antibody titer was 10(6) and the monoclonal antibody affinity constants was 2.90 x 10(10) L/mol. The result of the indirect competition ELISA confirmed that the monoclonal antibody had no cross-reaction with BSA and a few kind of CL analogue. CL detection standard curve based on indirect competition ELISA was established, which R2 was 0.9812, and the lowest detectable limit was 1.0 ng/ml.</p><p><b>CONCLUSION</b>The standard curve based on indirectly competitioning ELISA was established. The self-preparation monoclonal antibody which target to CL has high affinity and high specific to CL, which had established the foundation to the advanced development of the CL immune test paper and CL ELISA kit.</p>

Effect of Zhifei mixture combined western drugs on symptoms and signs of children with mycoplasma pneumonia / 中国中西医结合杂志

<p><b>OBJECTIVE</b>To observe the effect of three Chinese medical formulae (Zhifei Mixture I , Zhfei Mixture II, and Zhifei Mixture II) on main and secondary symptoms and signs of children with Totally 70 mycoplasma pneumonia in treating three types of children mycoplasma pneumonia.</p><p><b>METHODS</b>children with mycoplasma pneumonia were assigned to the control group (38 cases) and the treatment group (32 case). All patients were intravenously injected with Azithromycin and took Ambroxol Hydrochloride and Clenbuterol Hydrochloride Oral Solution. Those in the treatment group additionally took Zhifei Mixture I , Zhfei Mixture II, and Zhifei Mixture Ill by syndrome typing. Their main and secondary symptoms and signs were observed before and after treatment (main symptoms and signs covered fever, cough, abundant sputum, short breath, and anoxia; secondary symptoms and signs covered aversion to cold, heart rate, facial complexion, spirit, appetite, and sweating).</p><p><b>RESULTS</b>Seven patients were lost in this study. Compared with before treatment in the same group, scores for main and secondary symptoms and signs decreased in the treatment group (P <0.01). The therapeutic effect on fever and cough was obviously better in the control group (P <0.01). The main and secondary symptoms and signs were more obviously improved in the treatment group than in the control group (P <0.01). Commpared with the control group, scores for main and secondary symptoms and signs decreased more in the treatment group (P <0.01). Patients' main and secondary symptoms and signs were more obviously improved (P <0.05).</p><p><b>CONCLUSIONS</b>Zhifei Mixture combined Western drugs could significantly improve main and secondary symptoms and signs of mycoplasma pneumonia children patients. Its efficacy was superior to that of using Western medicine alone.</p>

Clinical features and treatment of acute clenbuterol poisoning in children / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To study clinical features, treatment and curative effects in children with acute clenbuterol poisoning, in order to provide a basis for early diagnosis and treatment.</p><p><b>METHODS</b>Clinical data of 28 hospitalized children with acute clenbuterol poisoning in April 2011 were retrospectively studied.</p><p><b>RESULTS</b>Of the 28 patients, there were 15 males and 13 females, aged 1 to 13 years (mean age 6.5±4.8 years). Vomiting, palpitations and limb shaking were found as main clinical manifestations in the patients. Main changes of blood biochemical included hypokalemia, lactic acidosis, hyperglycemia, hypsocreatinkinase. Snus tachycardia and S-T segment depression were observed on ECG. Patients' symptoms were gradually alleviated after 12-78 hours by use of beta blockers, potassium supplement, protecting the heart and other symptomatic and supportive treatment. Blood biochemical indexes were improved after 48 hours of admission. All of the patients were cured after 5 days. The symptoms of the patients do not longer occur during a follow up of half a month.</p><p><b>CONCLUSIONS</b>Acute clenbuterol poisoning is characterized by vomiting, palpitations, limb shaking, hypokalemia, lactic acidosis and tachycardia in children. An early effective treatment of this disease can improve prognosis in children.</p>

Preparation of anti-salbutamol antibody based on a new designed immunogen and development of a heterologous indirect ELISA for detection of salbutamol residue / 药学学报

To synthesize salbutamol immunogen and develop an enzyme immunoassay (ELISA), a new salbutamol immunogen was synthesized using 4-aminobenzoic acid as a linker to connect hapten with carrier protein. An enzyme immunoassay based on the antibody prepared was developed and applied to detect salbutamol residue spiked in swine liver. An unusual coating antigen, clenbuterol-ovalbumin (OVA) conjugate instead of salbutamol-OVA conjugate, was used in the immunoassay and the results were discussed based on the structures of related compounds. The antibodies showed high sensitivity in the heterologous assay when using clenbuterol-OVA as a coating antigen, with an IC50 value of 8.97 ng mL(-1) toward salbutamol. The antibodies prepared showed high cross-reactivity with clenbuterol (107%) and were promising for the simultaneous determination of salbutamol and clenbuterol residues in food and food products. Recovery rates from the salbutamol-spiked swine liver samples were in the range of 70%-99%, while the intra-assay and inter-assay coefficients of variation were <13.3% and <14.3%, respectively. In summary, the antibodies of salbutamol have been successfully prepared. Sensitive and stable analysis for the detection of salbutamol residues in swine liver was obtained based on the competitive ELISA methods developed in this study.

Preparation of clenbuterol monoclonal antibody with subtractive immunization method / 中国应用生理学杂志

<p><b>AIM</b>To obtain Clenbuterol monoclonal antibodies.</p><p><b>METHODS</b>Clenbuterol complete antigen was prepared with diazotization method. BALB/c mice was immunized with subtractive immunization, Clenbuterol monoclonal antibody was prepared with rule hybridoma technique.</p><p><b>RESULTS</b>The mice obtained tolerance to BSA by subtractive immunization. The rate of the hybridoma cell with positive reaction which had obtained was 8.2%, and the specific clenbuterol monoclonal antibody was obtained at last.</p><p><b>CONCLUSION</b>Monoclonal antibodies to micromolecule contaminant be prepared by subtractive immunization, could decrease the workload in the bolting of monoclonal antibodies, and increase the chance to obtain the antibody of expected.</p>

Development of a high-throughput suspension microarray technology for detection of three kinds of veterinary drug residues: chloramphenicol, clenbuterol and 17-beta-estradiol / 中华预防医学杂志

<p><b>OBJECTIVE</b>To establish a novel suspension microarray technology for the detection of three kinds of veterinary drug residues: chloramphenicol, clenbuterol and 17-beta-estradiol (CAP, CL and E2).</p><p><b>METHODS</b>The three conjugates that veterinary drug coupled with bovine serum albumin (BSA) were synthesized and identified by ultraviolet (UV) spectrophotometry and mass spectrum. The veterinary drug conjugates were immobilized on the polystyrene fluorescent microspheres/beads. There were competitive reactions between the veterinary drugs in the aqueous phase and that on the beads for combination with their specific biotinylated monoclonal antibodies. The optimum amount of the veterinary drug conjugates and the antibodies were optimized and selected. The detective standard curves were plotted. The specificity and the unknown samples were also determined by grouping according to different concentrations of the interferes and the samples. Meantime, the different microstructures of the surfaces of the beads were also observed by scanning electron microscope.</p><p><b>RESULTS</b>Couplings were completed between small molecular veterinary drugs and BSA. The amounts of the three conjugates and the antibodies were optimized. The detective standard curves of the suspension array and their corresponding coefficients of determination (R2) were good (R2 > 0.99). The detection ranges of the three veterinary drugs were (40.00 - 6.25) x 10(5) ng/L, (50.00-7.81) x 10(5) ng/L and 1.00 x 10(3) - 7.29 x 10(5) ng/L respectively. Simultaneously, the specific detection of the suspension microarray was excellent and did not indicate significant cross-reactions. Errors between the found and the real are in the range of 8.09% - 17.03%. It can be considered that the relative standard deviations were relatively small. Successful couplings were also directly confirmed by the observation for microstructures of the surfaces of the beads by scanning of electron microscope and laid good foundation for the following responses.</p><p><b>CONCLUSION</b>The high-throughput suspension microarray should provide a novel method for multi-analysis of the veterinary drugs and have a wide applicative prospects with simple operation, sensitive, rapid and low cost.</p>

The effect of a low dose of clenbuterol on rat soleus muscle submitted to joint immobilization

The aim of the present study was to evaluate the effect of joint immobilization on morphometric parameters and glycogen content of soleus muscle treated with clenbuterol. Male Wistar (3-4 months old) rats were divided into 4 groups (N = 6 for each group): control, clenbuterol, immobilized, and immobilized treated with clenbuterol. Immobilization was performed with acrylic resin orthoses and 10 µg/kg body weight clenbuterol was administered subcutaneously for 7 days. The following parameters were measured the next day on soleus muscle: weight, glycogen content, cross-sectional area, and connective tissue content. The clenbuterol group showed an increase in glycogen (81.6 percent, 0.38 ± 0.09 vs 0.69 ± 0.06 mg/100 g; P < 0.05) without alteration in weight, cross-sectional area or connective tissue compared with the control group. The immobilized group showed a reduction in muscle weight (34.2 percent, 123.5 ± 5.3 vs 81.3 ± 4.6 mg; P < 0.05), glycogen content (31.6 percent, 0.38 ± 0.09 vs 0.26 ± 0.05 mg/100 mg; P < 0.05) and cross-sectional area (44.1 percent, 2574.9 ± 560.2 vs 1438.1 ± 352.2 µm²; P < 0.05) and an increase in connective tissue (216.5 percent, 8.82 ± 3.55 vs 27.92 ± 5.36 percent; P < 0.05). However, the immobilized + clenbuterol group showed an increase in weight (15.9 percent; 81.3 ± 4.6 vs 94.2 ± 4.3 mg; P < 0.05), glycogen content (92.3 percent, 0.26 ± 0.05 vs 0.50 ± 0.17 mg/100 mg; P < 0.05), and cross-sectional area (19.9 percent, 1438.1 ± 352.2 vs 1724.8 ± 365.5 µm²; P < 0.05) and a reduction in connective tissue (52.2 percent, 27.92 ± 5.36 vs 13.34 ± 6.86 percent; P < 0.05). Statistical analysis was performed using Kolmogorov-Smirnov and homoscedasticity tests. For the muscle weight and muscle glycogen content, two-way ANOVA and the Tukey test were used. For the cross-sectional area and connective tissue content, Kruskal-Wallis and Tukey tests were used. This study emphasizes the importance of anabolic pharmacological...

Construction and expression of anti-clenbuterol single chain Fv recombinant vector / 生物工程学报

To construct the recombinant vector pBV220-scFv and express anti-clenbuterol (CBL) scFv antibody in Escherichia coli, we amplified the scFv gene using plasmid pCANTABSE-CBL as a template, recombined it with pPICZalphaA, then amplified the scFv-His-tag gene from plasmid pPICZalphaA-scFv and linked it with expression plasmid pBV220. We identified the recombinant plasmid by restrictive enzyme digestion, PCR amplification and sequence analysis. Finally, we transformed the recombinant vector into E. coli DH5alpha that was temperature-induced and expressed recombinant protein. We identified the recombinant protein by SDS-PAGE, Western blotting and indirect competitive ELISA. The results show that recombinant plasmid pBV220-scFv contained the inserted fragment with highest homology about 99.8%. The expression of scFv induced by temperature show 37 kD Mw and anti-His-tag mAb recognized-activity by SDS-PAGE and Western blotting respectively, and could competitively combine with CBL, the IC50 is 4.55 ng/mL. The recombinant plasmid pBV220-scFv is constructed and expresses the scFv gene of CBL in E. coli successfully. This study suggests the corresponding immunoassay methods could be set up by the recombinant scFv.

Determination of ambroxol and clenbuterol in human plasma by LC-MS/MS method / 药学学报

Ambroxol and clenbuterol were extracted from human plasma samples by liquid-liquid extraction, ambroxol was separated on a Zorbax XDB-C18 column and detected by tandem mass spectrometry with an atmospheric pressure chemical ionization interface after oral administration of a compound preparation. Clenbuterol was separated on a Zorbax XDB-C8 column and detected by tandem mass spectrometry with an electrospray ionization interface. Diphenhydramine is used as the internal standard. The linear concentration ranges of the calibration curves for ambroxol and clenbuterol were 0.080 - 400 microg x L(-1) and 5.0 - 5 000 ng x L(-1), respectively. The lower limits of quantification were 0.080 microg x L(-1) for ambroxol and 5.0 ng x L(-1) for clenbuterol, individually. The inter-day and intra-day precision (RSD) across three validation run over the entire concentration range was below 7.5%, and the accuracy (RE) was within +/- 2.5% for both ambroxol and clenbuterol. The methods were used to determine the pharmacokinetic parameters of ambroxol and clenbuterol in human plasma after oral administration of a compound preparation containing 60 mg ambroxol hydrochloride and 40 microg clenbuterol hydrochloride. The method was proved to be highly sensitive, selective and suitable for the pharmacokinetic study of different compound preparations containing ambroxol and clenbuterol.

Ultrastructural study on the effect of dexamethasone with and without clenbuterol on the diaphragmatic muscle of adult male albino

Animal and clinical studies have shown respiratory muscle dysfunction caused by treatment with glucocorticoids. Beta-agonists and glucocorticoids are frequently coprescribed for chronic asthma treatment. This work was done to investigate whether clenbuterol was able to ameliorate the structural changes induced hr long-term low-dose dexamethasone administration. Muscle samples were obtained from five groups of adult rats: group I, represents the control rats; group II. represents Sham control animals, group III represents animals receiving clenbuterol orally; group IV represents animals receiving dexamethasone subcutaneously, whereas, group V represents animals receiving both, treatment [dexamethasone and clenbuterol]. At the end of 4th week, rats were anaesthetized, perfused with, 1.5% buffered gluteraldehyde and then sacrificed. The diaphragmatic muscle strips were immersed in 2.5% buffered gluteraldehyde for 24 hours, postfixed in 1% OsO[4] for 2 hours and then, processed to be examined with TEM. Dexamethasone induced myofibrillar disorganization and destruction. The distinct ban ding pattern of sarcomeres was lost. The mitochondria showed increased subsarcolemmal aggregation, transverse orientation, and destruction of their cristae. Sarcoplasmic reticulum showed irregularity, dilatation, and loss of their relationship to A-I junctions. Also, mononuclear cellular infiltration was observed. In combined treatments [DEX + CL], the changes induced by DEX alone were generally minimized. Dexamethasone could induce severe structural changes in the diaphragmatic muscle of rat, timid these changes could be generally minimized on concomitant administration of clenbuterol

Histological evidences of reparative and regenerative effects of beta-adrenoceptor agonists, clenbuterol and isoproterenol, in denervated rat skeletal muscle.

The aim of this study was to determine the contribution of beta-adrenoceptor activation in the reconstruction of the structural and functional organization of denervated skeletal muscle. beta-agonists, clenbuterol (1.2 mg/kg body weight) and isoproterenol (2 mg/kg body weight), administration (daily oral administration; maximum 7 days) to normal innervated rats as well as denervated animals caused muscle hypertrophy. An increase in mean fiber diameter confirmed this stimulated growth both in normal innervated and denervated rat gastrocnemius muscle. Examination of muscle nuclei from treated but normal innervated rat gastrocnemius exhibited features like large size, active nucleoplasm and an increase in their number per fiber cross section and per mm mean fiber length indicating towards an elevated biosynthetic activity in tissue in the presence of beta adrenoceptor agonists. Administration of drugs to normal innervated animals resulted in an emergence of central muscle nuclei. The hyperactive and enlarged muscle nuclei ultimately organized themselves into unusually elongated nuclear streaks. beta agonist treatment to denervated rats resulted in amelioration of atrophic state of tissue characterized by hypertrophy of muscle fibers thus lending to a restoration of structural organization of tissue. Bizarre shapes of nuclei in denervated muscle tend to recover to that characteristic to normal innervated muscle in presence of clenbuterol and isoproterenol hydrochloride. All observations were confirmed by administering butoxamine, a beta-adrenoceptor antagonist along with beta-agonists. The results suggests that both clenbuterol and isoproterenol hydrochloride are capable of mimicking normal innervation functions in skeletal muscle and thus play important role in the structural and functional reorganization of tissue. Amelioration of denervation atrophy in rat gastrocnemius in the presence of beta-agonists supports this.

Metabolic and physiologic characteristics of skeletal muscle determine its response to clenbuterol treatment.

beta-Adrenoceptor agonists are reported to induce skeletal muscle hypertrophy and hence serve as valuable adjunct to the treatment of wasting disorders. In the present study, we attempted to find out whether metabolic and physiologic characteristics of fibres are important in determining skeletal muscle response to clenbuterol (an adrenergic receptor agonist) therapy, as proposed in the treatment of wasting disorders. The treatment of mice with clenbuterol (2 mg/kg body wt for 30 days) resulted in skeletal muscle hypertrophy, more common amongst fast-twitch glycolytic fibres/muscle, with increase in body mass and a parallel rise in muscle mass to body mass ratio. Measurement of fibre diameters in soleus (rich in slow-twitch oxidative fibres), ALD or anterior latissimus dorsi (with a predominance of fast-twitch glycolytic fibres) and gastrocnemius (a mixed-type of muscle) from clenbuterol-treated mice for 30 days revealed noticeable increase in the per cent population of narrow slow-twitch fibre and a corresponding decline in white-type or fast-twitch glycolytic fibres in gastrocnemius and ALD. As revealed by counting of muscle cells in soleus, narrow red fibres declined with corresponding increase in white-type glycolytic fibres population. A significant decline in the succinic dehydrogenase activity was observed, thereby suggesting abnormality in oxidative activity of skeletal muscles in response to clenbuterol therapy.

Effets du clenbutérol sur l'expression de l'IGF-1 et des IGFPBs par les cellules musculaires C2C12

Nous avons etudie les effets du clenbuterol; un agoniste du recepteur ?2-adrenergique entrainant l'hypertrophie musculaire; sur l'expression de l'IGF-1 et des IGFBPs par les myotubes de cellules C2C12 en culture. A la concentration de 10-4 M; le clenbuterol a entraine une augmentation du niveau de l'ARN messager de l'IGF-1; IGFBP-4 et de l'IGFBP-5. L'effet sur l'IGFBP-5 est apparu apres 24h alors que les effets sur l'IGF-1 et l'IGFBP-4; plus tardifs; ont ete observes au bout de 48 heures d'incubation. Ces resultats montrent que le clenbuterol agit directement sur les cellules musculaires pour augmenter de l'expression de l'IGF-1 et des IGFBPs; mediateurs possibles de l'hypertrophie musculaire

Clenbuterol treatment stimulates cell proliferation in denervated chick gastrocnemius muscle.

Daily administration of clenbuterol, a beta adrenoceptor agonist (0.5 mg/kg body weight; for 7 days) to normal innervated and denervated adult chicks (Gallus domesticus) resulted in different growth related responses by gastrocnemius muscle. While normal innervated muscle undergoes hypertrophy, structural reorganization in denervated tissue is accomplished by the de novo emergence of new cells. A contrasting cell population with extremely narrow cross sectional dimensions is a characteristic feature of denervated muscle in presence of clenbuterol. Measurement of fiber dimensions, number of cells per unit area and examination of histochemical preparations support this.

Contraction and Relaxation Responses of Isolated Rabbit Seminal Vesicle to Selective beta Subtypes-adrenoceptor Agonists and Antagonists / 대한비뇨기과학회지

PURPOSE: This study was aimed at investigating the role of betaadrenoceptor subtypes in mediating the relaxation and contraction of seminal vesicles in rabbits. MATERIALS AND METHODS: Relaxation or contractile responses of epithelium- removed muscle strips of a rabbit seminal vesicle, which were precontracted with 10-5M norepinephrine, to selective betasubtypes-adrenoceptor agonists were observed in an organ bath. The contractile responses induced by isoproterenol were also observed after application of selective antagonists. RESULTS: Isoproterenol showed a concentration-dependent contractile response, but the contractility was weaker than those with phenylephrine and norepinephrine. The betaselective-agonists(xamoterol for beta, clenbuterol for beta and BRL37344 for beta) alone evoked neither contraction nor relaxation. However, the beta- and beta-agonists inhibited the contraction of the precontracted strips with 10-5M norepinephrine, while the beta-agonist enhanced the contraction. The pretreatment with a beta-antagonist(ICI118551) reduced the tension of the strips developed by 10-4M isoproterenol, but the beta-(atenolol) and beta-(SR59230A) antagonists showed no changes in the response. CONCLUSIONS: beta- and beta-adrenoceptors seem to mediate the relaxation of the seminal vesicle, while the beta-adrenoceptor may have a supplementary role in contraction.

Determination of residual clenbuterol in pork meat and liver by HPLC with electrochemical detection / 药学学报

<p><b>AIM</b>To detect the residual clenbuterol in pork meat and liver using HPLC with Coulometric electrode array system.</p><p><b>METHODS</b>Homogenized meat or liver sample was treated with 1 mol x L(-1) hydrochloric acid and centrifuged, the fat existing in meat or liver tissue was removed by diethyl ether. The pH of the remaining aqueous layer was adjusted to 10.8 +/- 0.2 or 11.6 +/- 0.2 for meat or liver and liquid-liquid extraction with diethyl ether was followed. The ether extract was evaporated to dryness, the residue was dissolved in the mobile phase. The mobile phase A consisted of 50 mmol x L(-1) phosphoric acid-30 mmol x L(-1) triethylamine and was adjusted to pH 4.0 with 2 mol x L(-1) sodium hydroxide solution. The mobile phase B consisted of methanol-acetonitrile (30:45). A mixture of mobile phase A and B (80:20) was used in the method. A four electrode array module was selected for quantitation, the electrode potentials were set at 450, 600, 650 and 680 mV respectively.</p><p><b>RESULTS</b>The two calibration curves for meat and liver showed good linearity between 1.88 - 60.16 ng x g(-1), the detection limit of clenbuterol was 1.2 ng x g(-1).</p><p><b>CONCLUSION</b>This method using HPLC-electrochemical detection is reproducible, and the sensitivity is good enough for the determination of clenbuterol in meat and liver.</p>

Clenbuterol induced changes in cholesterol and triglyceride levels of gastrocnemius, pectoralis and heart of rat under work induced stress.

Work induced stress led to decreased cholesterol and fluctuating triglyceride levels in gastrocnemius and pectoralis muscles in rats. But the drug (clenbuterol, 2 mg kg(-1) day(-1)) treatment increased cholesterol and triglyceride levels in both the muscles. However, heart showed decreased cholesterol and increased triglyceride level in the animals under work stress, but at the same time drug treatment led to a significant increase in levels of the two lipid fractions, inferring towards deleterious effect of the drug on heart.

Analysis on Clenbuterol pollution in swine products in Beijing, 2002 / 中华流行病学杂志

<p><b>OBJECTIVE</b>To explore the status of clenbuterol pollution in swine products in Beijing city in 2002.</p><p><b>METHODS</b>European Union method (EUR 15127-EN Cy2.3) was adopted to examine the samples. Samples were screened by enzyme-linked immunosorbent assay (ELISA) and confirmed by GC-MS. Detected limit of the method was 0.5 micro g/kg. Samples, including lung, liver, pork, kidney and urine of swine, were collected from slaughterhouses, refrigeratories and markets in 11 districts of Beijing.</p><p><b>RESULTS</b>The results indicated that 185 out of 1 379 samples were positive with an annual positive rate of 13.4%. The highest was 15.7% in lung of swine, followed by urine 15.2% and pork liver 14.0%.</p><p><b>CONCLUSION</b>Rates of detection had decreased from 30.0% to 2.7% during 2002.</p>

Effects of clenbuterol on nitrogen metabolism and G6PDH activity of rat hepatocyte / 药学学报

<p><b>AIM</b>To study the effects of beta 2-adrenergic receptor-selective agonist clenbuterol on nitrogen metabolism and glucose-6-phosphate dehydrogenase activity of rat hepatocyte and its pharmacological mechanism.</p><p><b>METHODS</b>Biochemical methods were used to study the influence of clenbuterol on urea-nitrogen concentration of hepatocyte culture medium, 3H-leucine incorporation into hepatocyte, insulin-like growth factor I (IGF-I) production and glucose-6-phosphate dehydrogenase (G6PDH) activity of rat hepatocyte.</p><p><b>RESULTS</b>The results showed that urea-nitrogen production by cultured rat hepatocytes was markedly affected with clenbuterol treatment (1 x 10(-6) mol.L-1), urea-nitrogen concentration of culture medium was decreased by 25.51% (P < 0.05) compared with control. The inhibitory effect of hepatocyte urea-nitrogen production of clenbuterol was blocked by propranolol, a beta-adrenoreceptor antagonist (1 x 10(-6) mol.L-1), but hepatocyte urea-nitrogen level was not affected with propranolol treatment only (P > 0.05). The content of 3H-leucine incorporation in rat hepatocyte was significantly increased by 23.35% (P < 0.05) with clenbuterol-treatment (1 x 10(-6) mol.L-1), and the enhanced effect of 3H-leucine incorporation into hepatocyte was antagonized by propranolol (1 x 10(-6) mol.L-1. The level of 3H-leucine incorporation of rat hepatocyte was not influenced by propranolol alone. IGF-I production of rat hepatocyte might be affected by clenbuterol. IGF-I concentration of culture medium was increased by 39.46% with clenbuterol (1 x 10(-6) mol.L-1), but no significant difference was found compared with the control (P > 0.05). Moreover, G6PDH activity of rat hepatocyte was significantly decreased by 43.36% (P < 0.05) with clenbuterol treatment (1 x 10(-6) mol.L-1), and the declined effect of clenbuterol was antagonized by propranolol. G6PDH activity of rat hepatocyte was not affected on condition that propranolol was administered alone (P > 0.05).</p><p><b>CONCLUSION</b>It is suggested that clenbuterol may regulate nitrogen and fat metabolism by means of increasing nitrogen retention and protein synthesis, and decreasing G6PDH activity of rat hepatocyte for pharmacological effects.</p>

Effects of clenbuterol on the hepatic flux of nitrogen, VFA and glucose in sheep / 中国应用生理学杂志

<p><b>AIM</b>To examine the liver mechanism with which clenbuterol (CL) is explained how to affect growth metabolism.</p><p><b>METHODS</b>The technique of chronic poly catheter was used to study the effects of CL (0.8 mg/kg b w) on the hepatic flux of nitrogen, VFA and glucose in 4 sheep.</p><p><b>RESULTS</b>The urea-nitrogen flux in CL-treated period always was lower than that in control during 24 h. The average flux of urea-nitrogen in hepatic and portal vein were decreased by 16.86% (P < 0.01) and 15.51% (P < 0.05), respectively, compared with that of control. The peptide level in hepatic vein was decreased with the treatment of CL, average flux of peptide was decreased by 38.71% (P < 0.01). But the peptide level of portal vein in CL treatment period was similar to control. Moreover, VFA level in the portal vein was enhanced by CL, the average flux of acetate in portal vein was increased by 19.49% (P < 0.01). No difference of VFA level in hepatic vein was noted between CL-treated period and control. In addition, the glucose flux in hepatic vein was obviously increased with CL treatment, the average flux of glucose was increased by 25.96% (P < 0.01). And glucose flux in portal vein was also elevated during CL-treated period.</p><p><b>CONCLUSION</b>CL can affect growth metabolism of animal with increasing nitrogen deposition, improving absorption and utilization of VFA and enhancing glucose synthesis in sheep liver.</p>