Effect of ritodrine on uteroplacental blood flow and cardiac output distribution in unanesthetized pregnant guinea pigs.
The effects of ritodrine, 15 micrograms X min-1 X kg-1 infused intravenously for 2 hours, on cardiac output distribution and uteroplacental blood flow were investigated in 10 chronically catheterized guinea pigs between 57 and 63 days of pregnancy. Ritodrine produced an average 29% increase in cardiac output, three quarters of which was distributed to the carcass and myocardium. Absolute placental blood flow decreased by 10%, and the placental fraction of cardiac output decreased by one third. Uteroplacental vascular resistance increased by 41% during ritodrine infusion. The proportional changes in placental blood flow were positively correlated and those in placental vascular resistance negatively correlated with the change in cardiac output.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D005260:Female; D006168:Guinea Pigs; D007263:Infusions, Parenteral; D008431:Maternal-Fetal Exchange / Q000187:drug effects; D010920:Placenta / Q000098:blood supply / Q000000981:diagnostic imaging / Q000187:drug effects*; D011247:Pregnancy; D011877:Radionuclide Imaging; D012039:Regional Blood Flow / Q000187:drug effects; D012312:Ritodrine / Q000494:pharmacology*; D014599:Uterus / Q000098:blood supply / Q000000981:diagnostic imaging / Q000187:drug effects*; D014655:Vascular Resistance / Q000187:drug effects
D012312:Ritodrine