The effects of oxytocin on the pulmonary and systemic circulation in pregnant ewes.
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).
Roberts
N V
NV
Department of Anaesthesia, Monash Medical Centre, Monash University, Victoria.
Keast
P J
PJ
Brodeky
V
V
Oates
A
A
Ritchie
B C
BC
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
D010121:Oxytocin