CHANGES IN REGIONAL RENAL BLOOD-FLOW AFTER UNILATERAL NEPHRECTOMY USING THE TECHNIQUES OF AUTORADIOGRAPHY AND MICROAUTORADIOGRAPHY

Purpose: To determine alterations in regional renal blood flow followi ng unilateral nephrectomy using an autoradiographic technique. The rol e of prostaglandins and the sympathetic nervous system in the mediatio n of these changes was assessed. Materials and Methods: C-14 iodoantip yrine was used as a tracer to measure intrarenal blood flow in anaesth etised rats at multiple time points following nephrectomy. Autoradiogr aphs were produced from tissue sections. C-14 concentrations were meas ured from standards thus allowing blood flow values to be calculated. Results: Base line values for cortical and medullary blood flow were 8 06 +/- 63 and 373 +/- 39 ml./100 gm./min. (mean +/- SEM) respectively. At 2 hours post nephrectomy blood flow to both the cortex and medulla increased significantly (1152 +/- 54 and 594 +/- 37; p <0.05). Blood flow had returned to control levels by 24 hours and was maintained at 5 days post-nephrectomy. Multiple discrete regions of high blood flow within the cortex were observed. Microautoradiography defined the morp hological location of these discrete regions of higher blood flow as p eriglomerular vasculature. Diclofenac administration did not inhibit t he augmentation in cortical blood flow post-nephrectomy, while medulla ry blood flow fell below base line values at both 30 minutes and 2 hou rs following nephrectomy. Sympathetic denervation did not affect the c hanges in cortical blood flow seen following nephrectomy, but did amel iorate the changes in medullary blood flow. Conclusions: Significant, transient changes in regional renal blood flow occur in the residual k idney following unilateral nephrectomy. The interaction between vasoac tive mediators and the autonomic nervous system which produces changes in cortical blood flow is complex. It is evident, however, that medul lary blood flow is dependent on local prostaglandin production and is also influenced by sympathetic nervous supply.