Kidney function is critical in determining the level of arterial pressure and in the pathogenesis of hypertension. Important evidence comes from studies in which the level of blood pressure is dictated by the donor when kidneys are transplanted between genetically hypertensive and normotensive rats. We have hypothesized that pharmacotherapy modifies specific properties of the kidney, particularly the vasculature, such that after kidney transplantation, there are persistent changes in the level of arterial pressure. Consistent with previous studies, a 2-week aggressive treatment of adult (15 weeks) spontaneously hypertensive rats with an angiotensin-converting enzyme inhibitor (enalapril) combined with a low-salt diet induced a persistent change in the kidney and a decrease in arterial pressure (18%). These persistent changes in arterial pressure could be completely transferred to untreated adult spontaneously hypertensive rats by kidney transplantation (ie, pressure in untreated rats was decreased after transplantation of a kidney donated from a previously treated rat). Further, the importance of kidney-specific changes was demonstrated by finding that the treatment-induced lowering of arterial pressure was completely reversed by transferring an untreated kidney into a previously treated rat. The specific treatment-induced changes to the kidney included a decrease in structurally based renal vascular resistance that was similar to the persistent lowering of arterial pressure. These data provide evidence for a link between the treatment-induced changes in kidney vascular structure and the persistent lowering of arterial pressure. The findings also suggest that a key pharmacotherapeutic target in hypertension should be kidney-specific changes, such as renal vascular structure.