Shear stress dependent release of nitric oxide (NO) from the endothelium into the circulation and adjacent smooth muscle cells is a well accepted phenomenon. In contrast to these clear results on a suborgan level, the role of NO with respect to renal sodium handling, intrarenal blood flow and/or blood pressure regulation remains confusing. Making the problem even more complex, in several cases the same group of researchers reported different results in (seemingly) similar experimental setups. Surprisingly, in most of the reported studies the dynamic properties of the driving blood pressure (RPP) and/or renal blood flow (RBF) have been attracted very limited attention. The goal of the present study was, therefore, to investigate to which extend NO modulates the influence of defined blood pressure oscillations (BPO) on intrarenal blood flow. RPP was reduced to 80mmHg in chronically instrumented, freely moving SD - rats (CON: N=9; "NO-block": N=7, L-NNA 11.5mg/kg bwt/day, controlled sodium and water intake). In addition, 10mmHg-BPO with distinct frequencies in the range from 0.0025Hz to 0.32Hz were superimposed on the reduced RPP. Mean RPP was identical among all protocols. At lower frequencies no major differences between the groups were observed. Faster BPO (above 0.1Hz) induced a significant increase in RBF in CON. This frequency dependent effect was abolished by L-NNA.