title: The effects of oxytocin on the pulmonary and systemic circulation in pregnant ewes.
abstract: The haemodynamic effects of oxytocin on the pulmonary and systemic circulation were studied in six awake, pregnant (greater than 140 days gestation) ewes. Bolus doses of oxytocin 0.2 units/kg and then 0.8 units/kg were administered. A dose of 0.2 units/kg resulted in small but significant increases in mean pulmonary artery pressure (14%, P less than 0.05) and pulmonary vascular resistance (24%, P less than 0.05. A bolus of 0.8 units/kg resulted in a significant increase in mean arterial pressure (20%, P less than 0.05) and systemic vascular resistance (33%, P less than 0.05). Acute pulmonary hypertension was then induced with glass bead microemboli (150-200 microns), with an increase in pulmonary artery pressure of 26 mmHg and pulmonary vascular resistance of 448 dyn. s. cm-5. Boluses of oxytocin 0.2 and 0.8 units/kg were then administered. There were no significant changes, except for a 30% increase in systemic vascular resistance at one minute after oxytocin, 0.8 units/kg (P less than 0.05).
authors.affiliation: Department of Anaesthesia, Monash Medical Centre, Monash University, Victoria.
authors.forename: N V
authors.initials: NV
authors.lastname: Roberts
authors.forename: P J
authors.initials: PJ
authors.lastname: Keast
authors.forename: V
authors.initials: V
authors.lastname: Brodeky
authors.forename: A
authors.initials: A
authors.lastname: Oates
authors.forename: B C
authors.initials: BC
authors.lastname: Ritchie
mesh_terms: D000818:Animals; D016280:Atrial Function, Right / Q000187:drug effects; D001775:Blood Circulation / Q000187:drug effects*; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D005260:Female; D006976:Hypertension, Pulmonary / Q000503:physiopathology*; D010121:Oxytocin / Q000008:administration & dosage / Q000494:pharmacology*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000187:drug effects*; D011312:Pressure; D011651:Pulmonary Artery / Q000187:drug effects / Q000502:physiology; D011652:Pulmonary Circulation / Q000187:drug effects*; D011669:Pulmonary Wedge Pressure / Q000187:drug effects; D012756:Sheep; D014599:Uterus / Q000187:drug effects; D014655:Vascular Resistance / Q000187:drug effects
chemical_list: D010121:Oxytocin