Expression of beta-adrenergic receptor kinase subtypes in the pregnant rat myometrium.
OBJECTIVE
This study tested the hypothesis that the increase in uterine tachyphylaxis to beta-adrenergic stimulation during pregnancy is associated with increased expression of the beta-adrenergic receptor-inactivating protein kinases.


METHODS
Messenger ribonucleic acid was isolated from snap-frozen myometrium collected from nonpregnant and pregnant rats ranging from 10 to 22 days of gestation. Autoradiographic analysis of beta-adrenergic receptor-inactivating protein kinase messenger ribonucleic acid expression was performed after hybridization with specific complementary deoxyribonucleic acid probes for types 1 and 2 beta-adrenergic receptor-inactivating protein kinases. Probe-specific hybridization was normalized for ribosomal ribonucleic acid detected with methylene blue. Protein expression was detected by Western analysis with use of specific polyclonal antibodies.


RESULTS
Myometrial beta-adrenergic receptor-inactivating protein kinase type 2 messenger ribonucleic acid and protein levels increased during the course of pregnancy and in postpartum day 1. In contrast, type 1 levels remained unchanged during the same period. Estrogen treatment resulted in a modest 20% decrease in messenger ribonucleic acid levels of both subtypes. This effect was reversed with progesterone treatment.


CONCLUSIONS
These results suggest that the myometrium undergoes a functional remodeling late in pregnancy to a state promoting myometrial contractions. The increased myometrial expression of type 2 beta-adrenergic receptor-inactivating kinase may explain the decreased effectiveness of beta 2-adrenergic receptor-mediated contraction inhibition at the end of pregnancy and labor.
Ruzycky
A L
AL
Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Pittsburgh School of Medicine, PA, USA.
DeLoia
J A
JA
D000818:Animals; D019390:Arrestins / Q000235:genetics; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics*; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D015870:Gene Expression; D005865:Gestational Age; D009215:Myometrium / Q000201:enzymology*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D011374:Progesterone / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D051552:beta-Adrenergic Receptor Kinases; D000071557:beta-Arrestins
D019390:Arrestins; D012333:RNA, Messenger; D000071557:beta-Arrestins; D011374:Progesterone; D004958:Estradiol; D017868:Cyclic AMP-Dependent Protein Kinases; D051552:beta-Adrenergic Receptor Kinases