[Do the kidneys play an important role in the pathogenesis of "essential" hypertension?]

The Prague Hypertensive Rat (PHR) is a model of genetic hypertension derived from the Wistar strain, in which a normotensive parallel, the Prague Normotensive Rat (PNR), was also bred from the same parent pair. Thus, it is possible to transfer organs between both parallels without signs of rejection and without the use of immunosuppressive drugs. Unilateral nephrectomy and transplantation of one kidney within the PHR and PNR groups did not affect the systolic blood pressure (SBP). Transplantation of one kidney from PNR to a bilateral nephrectomized (BNX) PHR normalized the high SBP; and transplantation of one kidney from PHR to BNX PNR led to an elevation of SBP: hypertension "travels" with the kidney. When the development of high SBP in PHR was prevented for 2 months after weaning by antihypertensive drugs, transplantation of one kidney from these rats to BNX PNR always induced a sustained hypertension in the recipient. If a PHR was left with one original kidney in situ after transplantation of a "normotensive" kidney, the high blood pressure persisted until the original "hypertensive" kidney was removed. These results support the view that the kidney of PHR produces a "hypertensinogenic" substance, the secretion of which is genetically determined and is not influenced by the magnitude of the SBP.