In:
Gynecologic and Obstetric Investigation, S. Karger AG, Vol. 45, No. 3 ( 1998), p. 145-150
Abstract:
The aim of the present investigation was to determine which subtypes of the α 〈 sub 〉 2 〈 /sub 〉 -adrenoceptors are being expressed in the human pregnant myometrium at term pregnancy. In radioligand binding studies, the specific binding of [ 〈 sup 〉 3 〈 /sup 〉 H]rauwolscine to human myometrial membranes was specific and of high affinity with K 〈 sub 〉 d 〈 /sub 〉 of 2.8 ± 0.6 n 〈 i 〉 M 〈 /i 〉 and B 〈 sub 〉 max 〈 /sub 〉 of 95 ± 5 fmol/mg protein. Results from competition for the binding of [ 〈 sup 〉 3 〈 /sup 〉 H]rauwolscine using subtype-selective ligands, oxymetazoline (α 〈 sub 〉 2 〈 /sub 〉 A-subptype), chlorpromazine (α 〈 sub 〉 2 〈 /sub 〉 B-subtype) and prazosin (α 〈 sub 〉 2 〈 /sub 〉 B-α 〈 sub 〉 2 〈 /sub 〉 C-subtype), suggested that the α 〈 sub 〉 2 〈 /sub 〉 A- and α 〈 sub 〉 2 〈 /sub 〉 B-subtypes are being co-expressed. In order to examine if also the α 〈 sub 〉 2 〈 /sub 〉 C-subtype is being expressed we used an optimal concentration of oxymetazoline or chlorpromazine which would block the high-affinity site, equivalent to the α 〈 sub 〉 2 〈 /sub 〉 A- and α 〈 sub 〉 2 〈 /sub 〉 B-subtype respectively. Competition curves of both oxymetazoline and chlorpromazine still showed a significantly better fit using a two-site model, suggesting that the α 〈 sub 〉 2 〈 /sub 〉 C-subtype also is being expressed. The expression of α 〈 sub 〉 2 〈 /sub 〉 C-subtype mRNA was confirmed using reverse transcription-polymerase chain reaction on mRNA isolated from myometrial biopsies.In conclusion, our results suggest that all three subtypes of α 〈 sub 〉 2 〈 /sub 〉 -adrenoceptors are being coexpressed in the human myometrium at term pregnancy and that α 〈 sub 〉 2 〈 /sub 〉 -expression is dominated by the α 〈 sub 〉 2 〈 /sub 〉 A-subtype.
Type of Medium:
Online Resource
ISSN:
0378-7346
,
1423-002X
Language:
English
Publisher:
S. Karger AG
Publication Date:
1998
detail.hit.zdb_id:
1482695-1
