Identification and characterization of α2-adrenergic receptors in human myometrium by [3H]rauwolscine binding

Bottari, Serge P.; Vokaer, Alain; Kaivez, Etienne; Lescrainier, Jean Paul; Vauquelin, Georges

doi:10.1016/0002-9378(83)91005-0

Cited by 19 publications

(4 citation statements)

References 23 publications

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“…yohimbine ≥ clonidine > noradre‐naline > phenylephrine > propranolol. These results, as those obtained by Scatchard plot on human and rat pregnant myometrium, support previous radioligand binding data (Bottari et al , 1983; Maltier & Legrand, 1985; Dahle et al , 1993).…”

Section: Discussionsupporting

confidence: 91%

“…In binding studies myometrial plasma membranes (200–300 μg) were incubated as described previously at 25°C for 20 min with the required concentrations of [ 3 H]‐rauwolscine (Bottari et al , 1983; Legrand et al , 1993). Non specific binding was defined in the presence of 10 μM phentolamine.…”

Section: Methodsmentioning

confidence: 99%

“…In man, pharmacological studies have previously identified α 2 ‐adrenoceptors on myometrium (Bottari et al , 1983; Breuiller et al , 1990; Dahle et al , 1993). However, in none of these studies were the subtype(s) expressed characterized or quantified.…”

Section: Introductionmentioning

confidence: 99%

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Heterogeneity of α₂‐adrenoceptors in human and rat myometrium and differential expression during pregnancy

Bouet-Alard

Mhaouty-Kodja

Limon

et al. 1997

British J Pharmacology

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1 The aim of this study was ®rst, to characterize a 2 -adrenoceptor subtypes in human and rat pregnant myometrium and second, to investigate the possibility of a di erential expression of the putative subtypes according to the stage of pregnancy. 2 In both species, speci®c [ 3 H]-rauwolscine binding was inhibited by ®ve di erent compounds with an order of a nity characteristic of the one described for a 2 -adrenoceptors (yohimbine5clonidine4nor-adrenaline4phenylephrine4propranolol). Binding a nities (pK i ) for the compounds tested were, in human and rat, respectively: 7.63 and 8.93 for yohimbine, 6.91 and 8.71 for clonidine, 6.23 and 6.09 for noradrenaline, 5.37 and 5.73 for phenylephrine, 4.64 and 4.72 for propranolol. 3 By use of non-linear iterative curve ®tting procedures and by ®tting the data to a two-site model, analysis of [ 3 H]-rauwolscine inhibition binding curves performed in the presence of oxymetazoline (a 2A -selective), ARC239, prazosin or chlorpromazine (a 2B -and a 2C -selective) indicated that pregnant human and rat myometrium contain at least two pharmacologically distinct a 2 -adrenoceptor subtypes (a 2A , a 2B and/or a 2C ). RNA blot analysis with probes speci®c for each cloned human and rat a 2 -adrenoceptor subtype demonstrated that a 2A -and a 2B -subtypes were present in both species but a 2C seems to be expressed only in human tissues. 4 In the pregnant rat myometrium, subtype selective compounds competition curves revealed a predominant expression of a 2A -adrenoceptors at mid-pregnancy whereas, at term, a 2A -and a 2B -subtypes density reached approximately the same level (a 2A : a 2B ratio=73 : 27 at mid-pregnancy and=43 : 57 at term). In addition, quanti®cation of a 2A -and a 2B -transcripts by densitometry, following data normalization with an oligo(dT) 12 ± 18 probe, showed a pattern of expression comparable to the one characterized by pharmacological studies. 5 In conclusion, these data demonstrate heterogeneity of a 2 -adrenoceptors in pregnant human and rat myometria and an alteration of the a 2A -/a 2B -subtypes expression pattern during rat pregnancy. Such observations lead us to suggest a multiple role for a 2 -adrenoceptors in regulating speci®c functions of myometrium throughout the time course of pregnancy.

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Section: Discussionsupporting

confidence: 91%

Section: Methodsmentioning

confidence: 99%

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Heterogeneity of α₂‐adrenoceptors in human and rat myometrium and differential expression during pregnancy

Bouet-Alard

Mhaouty-Kodja

Limon

et al. 1997

British J Pharmacology

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“…The myometrial tissue was frozen and stored at -7 0 °C until analyzed using radioligand binding techniques. Radiolabeled di-antagonist [3H]-prazosin and d2-antagonist [TlJ-rauwolscine were used, both with well-docu mented high affinity and specificity to their respective receptor sub groups [14,15], As a rule, analysis of both dp and di-receptors was performed on the same biopsy, but in some cases (a total of 12) material was insuffi cient, permitting analysis of only 1 randomly selected receptor sub type. Ligands from different batches were used, and receptor analysis was performed at random with regards to pregnancy week and ligand batch.…”

Section: Methodsmentioning

confidence: 99%

Alpha-drenergic Receptors in Human Myometrium: Changes during Pregnancy

Dahle¹,

Andersson

Berg³

et al. 1993

Gynecol Obstet Invest

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Myometrial biopsies from 80 women, delivered by cesarean section in 26–42 completed weeks of pregnancy, were analyzed using radiolabeled Α₁-antagonist [³H]-prazosin and Α₁-antagonist [³H]-rauwolscine. Statistical analysis was performed using Student’s t test (two-tailed), where p < 0.05 was considered significant. The number of Α₂-adrenergic receptors did not vary (mean value weeks 37–39 =17.2 ± 1.3 fmol/mg protein), while the dissociation constant (K_d) for Α₂-receptors tended to increase with increasing gestational age, implying reduced affinity near term (p < 0.05, mean values 3.4 ± 0.2 nM). ΑpRecep-tors, however, increased significantly (p < 0.01) in the pregnancy weeks 37–39 (mean value 29.2 ± 2.9 fmol/mg prot) while K_d was unaltered. Increased number of Α₁-receptors, along with a decreased affinity of Α₂-receptors, could, in combination with other factors, play a role in the initiation of labor.

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Cellular Endocrinology

Bernal¹,

Watson²

1992

Prostaglandins and the Uterus

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Identification and characterization of α2-adrenergic receptors in human myometrium by [3H]rauwolscine binding

Cited by 19 publications

References 23 publications

Heterogeneity of α₂‐adrenoceptors in human and rat myometrium and differential expression during pregnancy

Heterogeneity of α₂‐adrenoceptors in human and rat myometrium and differential expression during pregnancy

Alpha-drenergic Receptors in Human Myometrium: Changes during Pregnancy

Cellular Endocrinology

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Identification and characterization of α2-adrenergic receptors in human myometrium by [3H]rauwolscine binding

Cited by 19 publications

References 23 publications

Heterogeneity of α2‐adrenoceptors in human and rat myometrium and differential expression during pregnancy

Heterogeneity of α2‐adrenoceptors in human and rat myometrium and differential expression during pregnancy

Alpha-drenergic Receptors in Human Myometrium: Changes during Pregnancy

Cellular Endocrinology

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Product

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Heterogeneity of α₂‐adrenoceptors in human and rat myometrium and differential expression during pregnancy

Heterogeneity of α₂‐adrenoceptors in human and rat myometrium and differential expression during pregnancy