engleski

Comparison of ractopamine accumulation in tissues on days after treatment

Ractopamine is a -adrenergic agonist that promotes muscle growth of animals by increasing nitrogen retention, protein synthesis and lipolysis, and suppressing lipogenesis. In European Union, the use of ractopamine in meat production, like other -agonists, is completely banned. The aim was to compare residue levels, i.e.accumulation potential of ractopamine in different tissues on days after repeat ractopamine administration. The experiment was carried out in 38 albino guinea pigs. Thirty of them were treated with ractopamine hydrochloride and 8 were untreated. Treated animals were orally administered ractopamine hydrochloride in a dose of 3.5 mg/kg body mass per day using probes for 7 consecutive days. On days 1, 10, 20 and 30 of drug discontinuation, animals were randomly sacrificed and the hair, liver, kidney, lung and muscle samples were collected. In all matrices, ractopamine concentration was determined using validated enzyme-linked immunosorbent assay (ELISA) as a quantitative screening method. The highest ractopamine concentration was recorded on day 1 in hair (114.07±29.39 ng/g), followed by the lungs (50.70±14.32 ng/g), kidney (18.55±3.43 ng/g) and liver (2.44±1.19 ng/g), whereas no residues were detectable in the muscle. Ten days after the last administration, drug residues were detected in hair and lungs, while the concentration in the kidney was around the method limit of detection. As ractopamine residues were detected in hair 30 days after treatment (8.01±2.22 ng/g), these results suggested that hair, even when nonpigmented, has the highest accumulation potential for ractopamine in comparison to other tissues investigated.

ractopamine; tissues; guinea pigs

DOI: 10.1016/j.toxlet.2012.03.360