Microsphere Measurement of Intrarenal Circulation of the Dog

Distribution of cortical blood flow was measured in the dog by a technique based on radionuclide-labeled microspheres. Initially it was necessary to test possible pitfalls of this technique. Completeness of trapping in the kidney, the effect on renal function, and the notion that microsphere distribution reflects blood flow distribution in the kidney cortex were studied. Renal vein blood contained less than 0.2 % of the microspheres (16.8^t diameter) found in the renal artery after an aortic injection. No impairment of CrAH (control 167 ± 4; postinjection 179 ± 31 ml/min), CIn (control 39.3 ± 6; postinjection 37.6 ± 2 ml/min), and Tm glucose (control 90.8 ± 13; postinjection 102 ± 24) was found using doses adequate to measure renal blood flow (5 mg/injection X 4 injections). After 4 injections of 50 mg each significant impairment of renal function was observed. Intrarenal blood flow distribution was determined during hemorrhagic hypotension. 3(li)Yb-labeled microspheres were injected into the root of the aorta before, and 85Sr-labeled microspheres after, acut