Veterinární Medicína (Oct 2003)
Alpha adrenergic receptors are involved in the contractile activity of neuropeptide Y in the porcine isolated ovarian artery
Abstract
The objective of this study was to determine whether α-adrenergic receptors are involved in the contractile activity of neuropeptide Y (NPY) in the porcine isolated ovarian artery collected from immature pigs and from the animals on day 1-5, 8-13 and 17-20 of the estrous cycle. NPY increased (P < 0.05) blood pressure in preparations collected form the immature and mature pigs. NPY administration into prazosin pre-treated vessels increased (P < 0.05) blood pressure in preparations of the immature and mature animals with the highest potency in the vessels from days 17-20 of the cycle. Simultaneous methoxamine and NPY treatment caused an increase (P < 0.05) in blood pressure in the vessels from all the periods examined with the highest potency in the preparations from days 17-20 of the cycle. NPY administration at the time of the maximum response to rauwolscine increased (P < 0.05) blood pressure in the preparations from the immature and mature pigs with the highest changes in the preparations from days 17-20 of the cycle. In clonidine pre-treated ovarian arteries, NPY insignificantly increased (P > 0.05) blood pressure in the preparations collected from the immature pigs and on days 1-5, 8-13 of the cycle, and significantly increased (P < 0.05) blood pressure in preparations from the animals on days 17-20 of the oestrous cycle. The present study has revealed that NPY increases blood pressure in the isolated porcine ovarian artery and that α-adrenergic receptors are involved in the vosocontractile action of this peptide. Moreover, the changes in the blood pressure caused by NPY alone or administered after α-adrenergic receptor agonists or antagonists treatment are dependent on steroid hormone concentrations.
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