Radioisotope studies in isolated perfused baboon kidneys

Radioisotopic studies were performed on baboon kidneys during isolated bloodless perfusion. The perfusion was equilibrated with either 100% oxygen or 100% helium gas. The clearance of 133Xe was found to be a very sensitive method in assessing renal circulation. Oxygen had a vasoconstrictive effect on the cortical vessels resulting in a decreased renal cortical perfusion flow. The distribution of labeled carbon microspheres did not reflect a difference in cortical flow during oxygen and helium exposure. Particles of the size employed did not remain fixed in the vascular tree. In some instances free or unbound isotope was detected. 203Hg chlormerodrin was poorly concentrated both during oxygen and helium exposure, presumably as a result of the absence of plasma proteins in the perfusate. Helium-exposed kidneys showed a more normal distribution and excretion of 131I hippuran than oxygen-exposed kidneys.