Cocaine downregulates beta-adrenergic receptors in pregnant sheep myometrium.
Cocaine abuse is associated with premature labor. Although cocaine is known to competitively inhibit beta-adrenergic receptor binding, cocaine's effect on receptor downregulation is uncertain. This study was designed to determine the in vitro effect of cocaine on downregulation of beta-adrenergic receptors in pregnant myometrium. Pregnant sheep myometrium was incubated with either cocaine, isoproterenol, or a cocaine metabolite, benzoylecgonine. Membrane fractions were assayed for beta-adrenergic receptors using (125I)-cyanopindolol and the beta 2-adrenergic antagonist ICI 118,551. We found that cocaine (10(-6) to 10(-4) mol/L), but not benzoylecgonine, downregulated both beta 1- and beta 2-adrenergic receptors, but did not further augment receptor downregulation by isoproterenol. The 46% decrease in beta-adrenergic receptors seen after exposure to cocaine was similar to the 53% decrease seen after isoproterenol. We hypothesize downregulation of beta-adrenergic receptors by cocaine may play a role in the association of cocaine abuse with premature labor.
Duke Scholars
Published In
DOI
ISSN
Publication Date
Volume
Issue
Start / End Page
Location
Related Subject Headings
- Toxicology
- Sheep
- Receptors, Adrenergic, beta
- Pregnancy
- Myometrium
- Isoproterenol
- Female
- Down-Regulation
- Cocaine
- Animals
Citation
Published In
DOI
ISSN
Publication Date
Volume
Issue
Start / End Page
Location
Related Subject Headings
- Toxicology
- Sheep
- Receptors, Adrenergic, beta
- Pregnancy
- Myometrium
- Isoproterenol
- Female
- Down-Regulation
- Cocaine
- Animals