Regional Cerebral Blood Flow in Dogs Using a Particle-Distribution Method ∗

Abstract

Summary

In this study a known activity of microspheres labeled with ¹⁶⁹Yb was injected into the left heart of lightly anesthetized dogs. Prior to injection of microspheres, cardiac output was determined by the isotope dilution technique using ⁴²K or ⁸⁶Rb. Blood flow to the cerebral cortex, white matter, thalamus, cerebellum, and caudate nucleus was determined in ml/min·g from fractional distribution of particles in tissue samples. Total brain blood flow in ml/min·g was estimated from the radioactivity observed in the remaining brain tissue. Comparison of dogs breathing air with dogs breathing 5% CO₂ showed that flow values were significantly increased (p<.05) with 5% CO₂ for all areas except white matter. Old dogs tended to show higher flow values than young dogs. Flow values obtained in this study were compared with values reported by others using different methods. The distribution of the particles in the brain was checked by autoradiography.