Role of the native kidney in experimental post-transplantation hypertension

In experimental renal transplantation studies using several animal models of primary hypertension, including stroke-prone spontaneously hypertensive rats (SHRSP) and their normotensive Wistar-Kyoto controls (WKY), single transplanted kidneys from genetically hypertensive but not normotensive donors elicited post-transplantation hypertension in bilaterally nephrectomized genetically normotensive recipients. The underlying mechanisms are presently unclear. The present study was designed to investigate the effects of a remaining native kidney on post-transplantation blood pressure, plasma renin activity and plasma angiotensin II concentration in (WKYxSHRSP) F1 hybrid recipients of a WKY or SHRSP kidney. The presence of a native kidney markedly reduced, but did not prevent, post-transplantation hypertension in recipients of an SHRSP kidney. WKY kidney grafts did not significantly alter blood pressure in bilaterally or unilaterally nephrectomized recipients. Plasma renin activity was lower in bilaterally than in unilaterally nephrectomized recipients, regardless of the source of the graft. The plasma angiotensin II concentration was similar in all groups. Renal graft function as assessed by 99mtechnetium-mercaptoacetyltriglycine scintigraphy was well preserved. These data suggest that post-transplantation hypertension in recipients of an SHRSP kidney may be partly due to the failure of the graft to eliminate a hypertensinogenic substance or to produce a blood pressure lowering agent.