Prostaglandin F2α modifies the action of norepinephrine on α- and β-adrenoceptors of isolated rat uterus
Cumulative dose-response curves were constructed for the effect of norepinephrine (NE) and isoproterenol (ISO) on the contractions of uterine strips from proestrous, estrous and metestrous rats. Both adrenergic agonists inhibited uterine spontaneous contractions in all three stages of the cycle. How...
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| Autores principales: | , , , , , |
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| Formato: | JOUR |
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| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_00142999_v78_n4_p449_Chaud |
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| Sumario: | Cumulative dose-response curves were constructed for the effect of norepinephrine (NE) and isoproterenol (ISO) on the contractions of uterine strips from proestrous, estrous and metestrous rats. Both adrenergic agonists inhibited uterine spontaneous contractions in all three stages of the cycle. However strips isolated from estrous rats were more sensitive to the inhibitory action of NE or ISO than preparations obtained from proestrous or metestrous animals. It was also observed that PGF-like material released by uterine horns was significantly higher during estrus than during proestrus or metestrus, whereas PGE-like material was significantly higher in metestrus than in estrus or proestrus. The EC50 of NE and ISO and the amount of PGF-like material generated by uterine horns correlated significantly during the three stages of the sex cycle. No correlation was found between the β-adrenergic inhibitory action of catecholamines and the PGE-like material released in the medium. A sub-threshold dose of PGF2α (10-10 M) shifted to the left the dose-response curves to NE of strips isolated from metestrous rats. When the tissue was pretreated with indomethacin and propranolol the dose-response curve to NE showed a clear shift to the left. On the other hand, the combination of indomethacin and propranolol shifted the NE dose-response curve to the right in the presence of sub-threshold doses of PGF2α. Dose-response curves to methoxamine were constructed in the presence or absence of several PGs using uterine strips isolated from estrous rats. With indomethacin, a threshold dose of PGE1 (10-8 M) and PGE2 (10-8 M) shifted to the left the control curve of methoxamine, whereas PGF2α (10-8 M) shifted the curve to the right. The interaction between sex hormones, PGs and catecholamines acting on α- and β-adrenoceptors in the isolated rat uterus is discussed. © 1982. |
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