The importance of the kidney in primary hypertension: insights from cross-transplantation.

Experimental renal cross-transplantation studies with genetically hypertensive and normotensive rats have shown that hypertension travels with the kidney. The underlying mechanisms are currently not well understood. Genetically normotensive recipients of a kidney from spontaneously hypertensive rats show a decreased capacity to excrete sodium when challenged with a high-salt diet. Furthermore, they retain more sodium than recipients of a kidney from genetically normotensive donors immediately after transplantation and removal of the native kidneys. Sodium retention precedes hypertension and may contribute to its development. Most recently, it has been shown that bilateral nephrectomy and transplantation of a genetically normotensive kidney attenuates the development of hypertension in young transplanted spontaneously hypertensive rats. Thus, long-term blood pressure in renal transplanted rats is critically determined by the genetic background of the renal graft. Together, these data indicate that genetically determined renal mechanisms play a major role in primary hypertension.