The effects of alpha-methyldopa on myometrial noradrenaline release and myometrial contractility in rat
Background. alpha-Methyldopa is a classic antihypertensive agent, used routinely in the treatment of pregnancy-induced hypertension. However, only a few data are available about its direct uterotropic effect. Accordingly, the aim of the present study was to investigate the direct effects of alpha-me...
Elmentve itt :
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| Dokumentumtípus: | Cikk |
| Megjelent: |
2007
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| Sorozat: | ACTA OBSTETRICIA ET GYNECOLOGICA SCANDINAVICA
86 No. 8 |
| Tárgyszavak: | |
| doi: | 10.1080/00016340701463830 |
| mtmt: | 1104357 |
| Online Access: | http://publicatio.bibl.u-szeged.hu/39779 |
| Tartalmi kivonat: | Background. alpha-Methyldopa is a classic antihypertensive agent, used routinely in the treatment of pregnancy-induced hypertension. However, only a few data are available about its direct uterotropic effect. Accordingly, the aim of the present study was to investigate the direct effects of alpha-methyldopa on the myometrial adrenergic functions in rat. Methods. The effects of alpha-methyldopa on the sympathetic transmission in the non-pregnant, early pregnant and late-pregnant myometrium were investigated by a superfusion technique. Myometrial samples from control and alpha-methyldopa-treated (200 mg/kg i.p. for 7 days) non-pregnant, 7-day and 21-day pregnant rats were saturated with [H-3] noradrenaline, and the liberation evoked by electric field stimulation was determined. The contractility responses to alpha-and beta-adrenergic stimulation were additionally characterised by generating concentration-response curves of myometrial rings to noradrenaline and terbutaline in the same arrangement. The changes in the density and affinity of the adrenergic receptors (alpha(2) and beta(2)) were investigated by a radioligand binding technique. Results. The treatment with alpha-methyldopa substantially decreased both the [H-3] noradrenaline uptake and release in both the non-pregnant and early pregnant uterus, while treatment-dependent changes were observed at term only in the uptake capacity. The contractility response to exogenous alpha-sympathomimetics was higher in the group treated in early pregnancy, and a decreased terbutaline-induced relaxation was observed in the non-pregnant state and at term. The treatment resulted in increased affinity for a 2 receptors in early pregnancy, while K-d for beta(2) was increased at term. Conclusions. Our experimental data suggest that besides its antihypertensive effect, alpha-methyldopa may influence the adrenergic transmission of the pregnant uterus. Our results indicate that the agent decreases the efficacy of beta(2)-adrenergic agonists at term pregnancy and increases the response to alpha-sympathomimetics in early pregnancy. |
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| Terjedelem/Fizikai jellemzők: | 986-994 |
| ISSN: | 0001-6349 |