Effect of isoproterenol on uterine blood flow and cardiac output distribution in pregnant guinea pigs.
The effects of isoproterenol, 0.05 micrograms X min-1 X kg-1 infused intravenously for 2 hours, on cardiac output distribution and uteroplacental blood flow were studied in six chronically catheterized guinea pigs between 60 and 68 days of pregnancy. Isoproterenol caused marked cardiac stimulation: Cardiac output was increased by 41%, of which 70% was distributed to the carcass and gastrointestinal tract. Absolute placental blood flow remained essentially unchanged, but the placental fraction of cardiac output decreased from 16% to 11%. Myometrial blood flow increased by 72%. Uteroplacental vascular resistance did not change significantly. In the guinea pig in late pregnancy beta-adrenergic receptors are present in the myoendometrial vessels but could not be demonstrated in the maternal vessels supplying the placenta.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects*; D005260:Female; D006168:Guinea Pigs; D006339:Heart Rate / Q000187:drug effects; D007545:Isoproterenol / Q000494:pharmacology*; D008863:Microspheres; D011247:Pregnancy; D011270:Pregnancy, Animal; D012039:Regional Blood Flow / Q000187:drug effects; D013318:Stroke Volume / Q000187:drug effects; D014599:Uterus / Q000098:blood supply*
D007545:Isoproterenol