Choroidal and cerebral blood flow in baboons measured by the external monitoring of radioactive inert gases.

Quantitative measurements of blood flow using xenon-133 to measure cerebral blood flow and krypton-85 to measure choroidal blood flow were made in 12 anesthetized baboons (Papio anubis). Analysis of the clearance curves of krypton from the eye and studies of the diffusion of krypton in the eye show that the inert gas-clearance method measures choroidal blood flow only. The mean choroidal blood flow at normocapnia in this group of baboons is 463 +/- 44 ml./100 mg./min., and the mean cerebral blood flow is 46 +/- 5 ml./100 mg./min. (mean +/- 1 S.D.).