Effects of isoprenaline and orciprenaline on the vascular bed of the mouse placenta.

High doses of isoprenaline or orciprenaline decreased the rate of transfer of tritium-labelled water from mother to fetus. The effect was blocked by propranolol. Maternal blood spaces of the placental labyrinth in the treated animals were congested with masses of red blood cells. These observations suggest that the placental circulation is impaired by high doses of beta-sympathomimetic drugs.