Comparison of three metrenperone dosage regimens inhibiting the 5-hydroxytryptamine-induced pulmonary dysfunction in cattle
1993
Linden, A.S. | Desmecht, D.J.M. | Amory, H. | Rollin, F.A. | Lekeux, P.M.
The effects of a 5-hydroxytryptamine 5-HT) challenge infusion on pulmonary function values were studied in healthy calves, pretreated with varying loses of metrenperone, a selective type 2 serotonergic 5-HT2) antagonist. In the first part of the experiment, the 5-HT challenge was performed 30 minutes after administration of metrenperone at a dose of 0.025 mg kg-l group 1, n = 8), 0.050 mg kg -1 (group 2, n = 8) and 0.100 mg kg-l group 3, n = 7). In the second part, the 5-HT challenge was performed 12 hours after administration of metrenperone at a dose of 0.050 mg kg-l group 4, n = 5) and 0.100 mg kg-1 group 5, n = 5). None of the three doses of metrenperone influenced the 5-Ht-induced ventilatory changes. For the challenge performed 30 minutes after blockade, all three doses inhibited the bronchoconstrictive process triggered by the 5-HT challenge. There was no dose-related inhibition. On the other hand, when the challenge was performed 12 hours after metrenperone, there was a dose-related inhibition with only the higher dose 0.100 mg kg-l) showing a significant efficacy in inhibiting 5-Ht-induced bronchoconstriction. It is concluded that, if 5-HT is involved in the pathophysiological processes of respiratory diseases in cattle, a 5-HT2 blockade with metrenperone at a dose rate of 0.100 mg kg-l and with a dosage interval of 12 hours should improve pulmonary function.
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