Changes of Renal Blood Flow Following Various Renal Denervation Procedures in Intact Kidneys of Rabbits Using Colored Microspheres

We investigated effects of acute renal denervation procedures on renal hemodynamics in intact kidneys of rabbits. Fifty-one Japanese white male rabbits were used. Renal blood flow (RBF) was measured by colored microspheres. In basic studies, first, colored microspheres 15 μm in diameter were histologically trapped within glomerular capillaries, indicating measurement of glomerular blood flow. Secondly, we used right kidney as control and left kidney as experimental side in each rabbit because there was no bilateral difference in normal RBF (n=15). Renal ischemia (n=8) was produced by clamping left renal artery for 10 min. Renal denervation procedures were produced by end-to-end anastomoses of renal artery (n =10), those of renal vein (n =10), and renal sympathectomy (n=8) by stripping the adventitia of left renal artery. Following reperfusion, bilateral RBF was measured by colored microspheres. At 5 min after reperfusion, RBF of renal ischemia increased to 146.2± 9.4 % of normal RBF(p=0.0018). At 5 min, RBF of end-to-end anastomoses of renal artery and renal sympathectomy decreased to 53.6 ± 6.7 % (p < 0.0001) and 64.7 ± 12.5 % (p =0.0258) of normal RBF, respectively. At 35 min, RBF of renal ischemia, end-to-end anastomoses of renal artery, and renal sympathectomy all recovered to normal RBF. Section of renal vein did not affect RBF responses. In summary, RBF is transiently decreased due to section of renal artery and renal sympathectomy, and acute renal denervation and/or vascular spasm may influence RBF. RBF in intact denervated kidneys all recovers to normal RBF at 35 min. These findings indicate that the renal sympathetic regulation of RBF is overruled by renal autoregulatory mechanism in initial renal hemodynamics after acute renal denervation.