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Effect of prazosin on the function of the teat sphincter in lactating cows

Published online by Cambridge University Press:  01 June 2009

Georgette Vandeputte-Van Messom ,
Jacques Bernabé ,
Christian Burvenich  and
Georges Peeters
Georgette Vandeputte-Van Messom
Affiliation:
Department of Physiology, Veterinary Faculty of the University of Ghent, Casinoplein 24, B-9000 Ghent, Belgium
Jacques Bernabé
Affiliation:
Institut National de la Recherche Agronomique, 35042 Rennes Cedex, France
Christian Burvenich
Affiliation:
Department of Physiology, Veterinary Faculty of the University of Ghent, Casinoplein 24, B-9000 Ghent, Belgium
Georges Peeters
Affiliation:
Department of Physiology, Veterinary Faculty of the University of Ghent, Casinoplein 24, B-9000 Ghent, Belgium
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Summary

Oxytocin was infused for 60 min into the jugular vein of 8 lactating cows with full udders before milking. Under these circumstances milk loss occurred spontaneously in 3 cows and was evoked in 5 cows by reducing pressure around one teat (–30 cm water) using a plethysmographic chamber. Milk loss was measured continuously. The postsynaptic α-blocking agent prazosin (PRZS) injected either into the udder artery (2 or 5 mg) or into the jugular vein (200 mg) consistently induced a significant increase in milk leakage. It is suggested that PRZS effectively inhibits α-adrenoceptors in the teat sphincter muscles and thus promotes the action of β-adrenoceptors, in this way inducing relaxation of the teat sphincter.

Type
Original Articles
Information
Journal of Dairy Research , Volume 51 , Issue 2 , May 1984 , pp. 219 - 226
Copyright
Copyright © Proprietors of Journal of Dairy Research 1984

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References

REFERENCES

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