الكاتب: Multiple References

B. RANHEIM* T. E. HORSBERG* N. E. SØLI* K. A. RYENG† & J. M. ARNEMO† *Department of Pharmacology, Microbiology and Food Hygiene, The Norwegian School of Veterinary Science, P.O. Box 8146 Dep., NO-0033 Oslo, Norway; † Department of Arctic Veterinary Medicine, The Norwegian School of Veterinary Science, NO-9292 Tromsø, Norway Ranheim, B., Horsberg, T. E., Søli, N. E., Ryeng, K. A., Arnemo, J. M. The effects of medetomidine and its reversal with atipamezole on plasma glucose, cortisol and noradrenaline in cattle and sheep. J. vet. Pharmacol. Therap. 23, 379–387. In the present study, we report the effect of medetomidine followed by atipamezole on plasma glucose, cortisol and noradrenaline in calves, cows and sheep. Eight calves, eight lactating dairy cows and eight adult female sheep were included in a crossover trial. The animals were injected i.v. with medetomidine (40 mg/kg), followed 60 min later by atipamezole i.v. (200 mg/ kg) or saline. The wash-out period between experiments was 1 or 2 weeks. In every animal, medetomidine induced a marked hyperglycaemia, which was reversed by atipamezole. Cortisol levels increased significantly in cows and sheep, reaching levels 4–8-fold higher than the baseline levels 25–45 min after injection of medetomidine. Atipamezole did not affect the cortisol levels, except in sheep where an increase was observed. Plasma levels of noradrenaline decreased in cows and sheep after medetomidine injection, reflecting the inhibition of sympathetic activity by the drug. After injection of the antagonist, there was a large increase in noradrenaline levels. In conclusion, a high dose of medetomidine does not seem to reduce the overall endocrine stress response in cattle and sheep, which has previously been reported in other species. (Paper received 1 September 1999; accepted for publication 26 August 2000) Birgit Ranheim, Department of Pharmacology, Microbiology and Food Hygiene, The Norwegian School of Veterinary Science, P.O. Box 8146 Dep., NO-0033 Oslo, Norway.