( sup 3 H)rauwolscine binding to myometrial. alpha. sub 2 -adrenoceptors in pregnant guinea pig

Journal Article · Thu Sep 01 00:00:00 EDT 1988 · American Journal of Physiology; (USA)

OSTI ID:7191887

Arkinstall, S J; Jones, C T ^[1]

---

1. Univ. of Oxford (England)

Uterine sympathetic nerves can exert an excitatory influence in late pregnancy and during parturition. Neuronal norepinephrine release is increased at these times and a diminished {alpha}{sub 2}-adrenoceptor-mediated prejunctional inhibition could account for this. To assess whether an altered receptor population may contribute, ({sup 3}H)rauwolscine was used to measure {alpha}{sub 2}-adrenoceptors in myometrial membranes at time intervals throughout pregnancy. High affinity ({sup 3}H)rauwolscine binding yielded linear Scatchard plots that in nonpregnant myometrium indicated a maximum binding density B{sub max} of 217 {plus minus} 42.4 fmol/mg protein. {alpha}{sub 2}-Adrenoceptor density was increased twofold at midpregnancy (31 days) and thereafter fell sharply by up to 90% toward term (67 {plus minus} 2 days). When uterine growth is accounted for and data are expressed in terms of total myometrial population, {alpha}{sub 2}-adrenoceptor number was eightfold (midpregnancy) and fourfold (term) greater than the nonpregnant value of 804 {plus minus} 322.4 fmol/uterus. {alpha}{sub 2}-Adrenoceptors were also found to bind dopamine with high affinity. These observations could indicate a pregnancy-related change in uterine sympathetic autoinhibitory capacity and, since {alpha}{sub 2}-adrenoceptors appear also to be located postjunctionally, explain in part reports of altered myometrial responsiveness to norepinephrine infusion and also the uterotonic actions of dopamine.

• OSTI ID: 7191887
• Journal Information: American Journal of Physiology; (USA), Vol. 255:3; ISSN 0002-9513
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
ANTIHYPERTENSIVE AGENTS
RADIORECEPTOR ASSAY
PREGNANCY
PHYSIOLOGY
UTERUS
ALKALOIDS
BIOCHEMICAL REACTION KINETICS
DOPAMINE
GUINEA PIGS
LIGANDS
RECEPTORS
SYMPATHOMIMETICS
TRITIUM COMPOUNDS
AMINES
ANIMALS
AROMATICS
AUTONOMIC NERVOUS SYSTEM AGENTS
BODY
CARDIOTONICS
CARDIOVASCULAR AGENTS
DRUGS
FEMALE GENITALS
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
ISOTOPE APPLICATIONS
KINETICS
MAMMALS
MEMBRANE PROTEINS
NEUROREGULATORS
ORGANIC COMPOUNDS
ORGANS
PHENOLS
POLYPHENOLS
PROTEINS
REACTION KINETICS
RODENTS
TRACER TECHNIQUES
VERTEBRATES
551001* - Physiological Systems- Tracer Techniques