Disease relevance of Ractopamine hydrochloride

• The growth rate for Salmonella Choleraesuis was increased with the addition of 2.0 mug ractopamine/ml compared with the other concentrations examined [1].
• Ractopamine, administered to sheep before and after oral inoculation with E. coli O157:H7, increased (P < 0.01) fecal shedding and tended to increase (P = 0.08) cecal populations of the challenge strain [1].
• Ractopamine increased (P < .05) feed intake (d 1 to 6); body weight; carcass CP; and intake, apparent absorption, retention, and retained:intake ratio of CP on d 1 to 6 of the study [2].
• Ractopamine HCl increased weight gain and efficiency of feed utilization when administered i.p. to rats, but not when administered orally [3].
• Additional supplementation of ractopamine hydrochloride for 6 weeks resulted in a tendency for increased weight loss [4].

High impact information on Ractopamine hydrochloride

• Ractopamine [1-(4-hydroxyphenyl-2-(1-methyl-3-(4-hydroxyphenyl)propylamino)ethanol] enhances protein accretion in skeletal muscle (sm) of pigs [5].
• FSR of sm alpha-actin was 55% greater in ractopamine-treated pigs than in controls [5].
• There was a trend for a lower ED50 in hindlimb with ractopamine treatment (P < 0.13) [6].
• The results suggest that ractopamine, when it improves performance and carcass composition, elicits a shift in metabolism involving increased use of fat for oxidation and potentiates the responsiveness of the adipose tissue to lipolytic cues [7].
• Ractopamine feeding had no effect on basal lipolysis and lipogenesis in vitro [7].

Biological context of Ractopamine hydrochloride

• Competition analysis using the tritiated antagonist dihydroalprenolol revealed receptor affinity for five structurally different beta-agonists, with IC50 values ranging from 2.1 +/- 0.76 x 10(-7) M for salmeterol to 1.1 +/- 0.62 x 10(-5) M for ractopamine [8].
• Because ractopamine metabolism has not been evaluated in turkeys, the objectives of this study were to synthesize and identify products of ractopamine metabolism and to determine the stereoselective metabolism and tissue distribution of [14C]ractopamine HCl in orally dosed turkey poults [9].
• No genotype x ractopamine interactions for the criteria described above were detected (P greater than .05) [10].
• After the hydrolysis of conjugates, ractopamine concentrations were 5,272+/-1,361 ppb on withdrawal d 0 and 178+/-78 ppb on withdrawal d 7 [11].
• Pigs with no added ractopamine demonstrated increased lean tissue accretion and improved efficiency and decreased fat tissue accretion with increasing energy intake (up to 9.5 Mcal of ME intake for barrows and 8.9 Mcal of ME intake for gilts) [12].

Anatomical context of Ractopamine hydrochloride

• These results indicate that ractopamine-enhanced ELC5 myotube protein accretion is mediated, at least in part, by stimulating cellular protein synthesis [13].
• Ractopamine (10(-6) mol/L) increased [35S]methionine incorporation (apparent protein synthesis) at 24 h (p less than 0.01), 48 h (p less than 0.05), 72 h (p less than 0.01) and 96 h (p less than 0.05) in cultured ELC5 muscle cells [13].
• Disposition of ractopamine residues in liver and pigmented retinal epithelium was determined in animals slaughtered with withdrawal periods of 0, 3, and 7 days [14].
• Therefore, we determined the betaAR subtypes that mediate the lipolytic response to ractopamine in swine adipocytes [15].
• Ractopamine completely relaxed the KCl-contracted guinea-pig trachea and rat costo-uterine smooth muscle to their resting tensions (EC50 = 3 x 10(-7) and 5.5 x 10(-8) M, respectively), indicative of full beta 2-agonist properties [16].

Associations of Ractopamine hydrochloride with other chemical compounds

• Skeletal muscle alpha-actin synthesis is increased pretranslationally in pigs fed the phenethanolamine ractopamine [5].
• Glucuronides conjugated to the C-10' phenol of ractopamine represented 12.7% of the urinary metabolites and were composed of the (1R,3R) and (1R,3S) stereoisomers [9].
• Determination of the affinity of ractopamine and clenbuterol for the beta-adrenoceptor of the porcine adipocyte [17].
• Similar cultures were used to examine the effects of ractopamine and isoproterenol on satellite cell proliferation [18].
• Determination of ractopamine hydrochloride in swine and turkey tissues by liquid chromatography with coulometric detection [19].

Gene context of Ractopamine hydrochloride

• We tested the effects of clenbuterol, a beta2-AR agonist, and ractopamine, a beta1/beta2-AR agonist, on growth, adiposity and adipose tissue apoptosis in male and female mice by feeding diets containing control, 200 ppm clenbuterol, or 200 or 800 ppm ractopamine [20].
• Relative to other beta-agonists, ractopamine was 100-fold more potent than the phenethanolamines, salbutamol and ritodrine, at the beta 1-adrenoceptor, and approximately 7- to 11-fold more potent than ritodrine, but only one-sixth to one-tenth as potent as salbutamol at the beta 2-adrenoceptor [16].
• Since the European Union banned hormonal growth promoters (HGPs) 15 years ago, countries such as Australia and the United States have licensed new products for livestock production, including bovine growth hormone (GH), porcine and equine GH, and the beta-agonist ractopamine [21].
• The LMA was increased by ractopamine in D x Wc and M x Wc pigs (P less than .05) but not in M pigs [22].
• Ractopamine treatment biases were found for equations in which midline backfat, ribbed carcass, and live ultrasonic measures were used as single technology sets of measurements [23].

Analytical, diagnostic and therapeutic context of Ractopamine hydrochloride

• We used the hyperinsulinemic, euglycemic clamp approach in five multicatheterized beef steers to evaluate insulin sensitivity (ED50) and responsiveness (Rmax or Rmin) during control or ractopamine feeding (80 mg/kg feed) [6].
• Liquid chromatography/electrospray tandem mass spectrometric analysis of incurred ractopamine residues in livestock tissues [14].
• Evaluation of ractopamine cross-reactivity in several commercially available beta-agonist enzyme immunoassay kits [24].
• A Testing Components Corporation enzyme-linked imunosorbent assay (ELISA) kit for ractopamine displayed linear response between 1.0 and 100 ng/mL with an I-50 of 10 ng/mL and an effective screening limit of detection of 50 ng/mL [25].
• A high-performance liquid chromatographic (HPLC) method is described for the determination of ractopamine (LY031537) in monkey plasma and swine serum [26].

References