Circulatory response to atropine in sheep fetus.

Atropine was given to the semichronic sheep fetus intravenously. Fetal heart rate, fetal perfusion pressure, and carotid blood flow increased. Cerebral blood flow was measured with the radioactive microsphere technique. Atropine was capable of increasing the cerebral blood flow. Elevation of carbon dioxide also caused an increase in cerebral blood flow, adding to the effect of atropine.