Concomitant Increase of G Protein-Coupled Receptor Kinase Activity and Uncoupling of β-Adrenergic Receptors in Rat Myometrium at Parturition

Apr 24, 2001Endocrinology

Increased receptor regulator activity and reduced receptor response in rat uterine muscle during childbirth

AI simplified

Circadian Biology on OpenScience ↗PubMed ↗DOI ↗

Abstract

A 190% increase in myometrial membrane-associated G protein-coupled receptor kinase activity occurs in the hours preceding parturition in rats.

The myometrial beta-adrenergic receptor pathway is significantly desensitized at the end of pregnancy.
GRK2, GRK5, GRK6, and a small amount of GRK3 were identified in late pregnant rat myometrium.
GRK activity was detected in both cytosolic and plasma membrane fractions.
Increased GRK activity is associated with enhanced membrane GRK2 levels.
These changes coincide with the uncoupling of beta-adrenergic receptors and may contribute to myometrial contractions at term.

AI simplified

The myometrial beta-adrenergic receptor (beta-AR)-adenylyl cyclase pathway is markedly desensitized at the end of pregnancy in the rat. We have investigated whether changes in the amount and/or the activity of G protein-coupled receptor kinase (GRK) occurred at the same period of pregnancy. Using Northern and Western blotting, we have identified GRK2, GRK5, GRK6, and a small amount of GRK3 in late pregnant rat myometrium. GRK activity, as measured by in vitro phosphorylation of rhodopsin, was detected in both cytosolic and plasma membrane fractions. Interestingly, in the 6-10 h preceding parturition, there was a substantial increase (+190%) of myometrial membrane-associated GRK activity. This was associated with an increase in membrane GRK2 immunoreactivity. Such alterations occurred concomitantly with uncoupling of beta-AR, as assessed by quantification of high-affinity binding receptors. These data suggest that GRK activity increase may be one of the mechanisms underlying alterations in the coupling between beta-AR and adenylyl cyclase and may thus contribute to the initiation of myometrial contractions at term.

Full Text

Full text is available at the source.

View full text ↗

Concomitant Increase of G Protein-Coupled Receptor Kinase Activity and Uncoupling of β-Adrenergic Receptors in Rat Myometrium at Parturition

Abstract

Full Text

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the circadian biology brief

Abstract

Full Text

Related papers

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the circadian biology brief