Characterization of alpha-adrenoceptors in the preprostatic urethra of sexually immature male lambs

European Journal of Pharmacology
A García-PascualA García-Sacristán

Abstract

Strips of preprostatic urethra from immature male lambs (3-4 months old) were used to study alpha-adrenoceptor-mediated contractions in vitro. The rank order of potency of the agonists was noradrenaline = phenylephrine greater than adrenaline. B-HT 920 was ineffective and clonidine behaved as a weak partial agonist. The rank order of efficacy was found to be noradrenaline greater than phenylephrine greater than adrenaline. Prazosin (10(-9)-10(-6) M) and rauwolscine (10(-6)-10(-4) M) antagonized noradrenaline-induced contractions. The pA2 values were 7.89 and 5.38 for prazosin and rauwolscine, respectively. Phenoxybenzamine reduced the maximal response to noradrenaline and shifted the concentration-response curve to the right. The dissociation constant (KA) of noradrenaline was calculated to be 4.05 +/- 0.21 x 10(-6) M and the occupancy-response plot for noradrenaline showed a linear relationship. It is concluded that alpha-adrenergic contraction of the preprostatic urethra from immature lambs are mediated by alpha 1-adrenoceptors. It is also suggested that the lack of a receptor reserve may affect the degree of urethral constriction and could be related to hormonal status.

References

Feb 11, 1986·European Journal of Pharmacology·F YablonskyJ P Dausse
Feb 1, 1984·British Journal of Pharmacology·K E AnderssonC Sjögren
Mar 1, 1959·British Journal of Pharmacology and Chemotherapy·O ARUNLAKSHANA, H O SCHILD

❮ Previous
Next ❯

Citations


❮ Previous
Next ❯

Related Concepts

Related Feeds

Adrenergic Receptors: Trafficking

Adrenergic receptor trafficking is an active physiological process where adrenergic receptors are relocated from one region of the cell to another or from one type of cell to another. Discover the latest research on adrenergic receptor trafficking here.