Regional and single glomerular blood flow in the rat kidney prepared for micropuncture. A methodological study

Regional renal and single glomerular blood flow was investigated in rats using 141-Ce and 85-Sr labelled microspheres. The kidneys were prepared for micropuncture and also the artery was catheterized with a steel cannula in order to make injections of 133-Xenon and vasoactive substances selectively into one kidney. The microspheres were first separated by sedimentation into a narrow fraction and then injected as a plasma suspension into the carotid arter; the two batches were infused at half an hour intervals. Single glomeruli were sampled from kidney sections with the aid of silicon rubber casts allowing the identification of the glomeruli both with respect to their localisation and their postglomerular appearance. The results showed a relatively high blood flow in the superficial and juxtamedullary glomeruli of above 100 nl/min per 100 g rat whereas in the other glomeruli the blood flow was about 70 nl/min per 100 g rat. No differences could be observed between the right untouched kidney and the left prepared for micropuncture. Futhermore no discrepancies between the results from the two injections could be found. The data on the total renal blood flow obtained by the 133-Xenon wash-out method agreed well with the microsphere method.