MUSIC 1A03 Lecture Notes - Lecture 7: Endoplasmic Reticulum, Inositol Trisphosphate, Gq Alpha Subunit
Document Summary
Any agent that stimulates the uterus to contract. Used for the induction or augmentation of labour and to control postpartum hemorrhage. Any agent that inhibits uterine contractions (induces relaxation of the uterine muscles) labour. Almost nothing will prevent an irritable uterus from contracting or going into: we can only slow it down. Requires the release of ca2+ from the sarcoplasmic reticulum in smooth muscle cells. Less camp, less phosphorylation of ca2+ sequestering proteins. Ip3 binds to the sarcoplasmic reticulum and stimulates ca2+ release. Increases frequency and force of uterine contractions. Iv administration: uterine response occurs almost immediately and subsides within one hour (induction & augmentation) Im injection: uterine response occurs within 3 to 5 minutes and persists for. No biological effect until oxytocin receptors are present in the myometrium. Oxytocin receptors do not appear until the 2nd half of gestation. Don"t want oxytocin to get stimulated early in pregnancy.
