Oxytocic And Tocolytics Flashcards
As the pregnancy gets closer to parturition, what hormonal shift happens?
Shifts from progesterone > estradiol dominance to estradiol > progesterone dominance
What effect does progesterone have on the pregnancy?
Causes hyperpolarization of myometrial cells (preventing contractions); decreases adrenergic receptors, inhibits oxytocin synthesis, inhibits estrogen receptor synthesis; promotes storage of prostaglandin synthesizing enzymes
What effect does progesterone have on the adrenergic of the uterus?
Decreases adrenergic receptors
Prior to parturition, what hormone inhibits synthesis of oxytocin receptors and estrogen receptors?
Progesterone
When closer to parturition and the hormones shift to estradiol > progesterone, what effect does this have on the uterus?
Promotes uterine contractility, increases oxytocin receptors, promotes cervical ripening, increases local prostaglandins release from the placenta (which cause myometrial contractions)
What effect do local prostaglandins released from the placenta have on the uterus?
Causes myometrial contractions
What prostaglandins predominate in reproduction?
PGF2 and PGE2
What is responsible for the mild Braxton Hicks contractions during pregnancy?
PGF2 and PGE2
What produces the prostaglandins important for contractions during parturition?
The placental unit
What is the function of oxytocin?
Induces smooth muscle contraction - important for myoepithelial cells in breast and myometrium in uterus
What do tocolytics do to the pregnancy?
Maintain pregnancy
What do oxcytocics do to pregnancy?
Promote labor
Where is oxytocin synthesized?
Paraventricular and supraoptic nuclei of the hypothalamus
What is neurophysin?
Oxytocin protein carrier protein
What kind of receptors are oxytocin receptors?
Gq - coupled to PLC
How is oxytocin administered?
Parenteral, sublingual, nasal; not orally
What is the drug of choice for labor induction?
Pitocin
What is Pitocin?
Synthetic oxytocin
What are contraindications of Pitocin?
Not intended as abortifacient; large baby; hypertonic uterine contractions; previous C sections
What prostaglandin contracts the uterus and produces hyperalgesia?
PGE2
What are the effects of PGE2 in regards to pregnancy/labor?
Contracts uterus; produces hyperalgesia; promotes softening of the cervix
PGER is coupled to what?
Gi