Effects of transplantation on the renin angiotensin system (RAS)

Hypertension in organ transplant recipients is associated with several functional modifications of the renin angiotensin system (RAS), which varies according to the type of transplanted organs (kidney, heart, liver or bone marrow) and the immunosuppressive regimen. Before transplantation, chronic organ failure is associated with direct and indirect stimulation of both systemic and local RASs. After transplantation, cyclosporin per se is the major determinant of hypertension. It induces stimulation of both systemic and local RAS via direct and indirect effects within the kidney and peripheral vessels. In kidney transplant recipients, ischaemia from the native kidneys and from the graft, due to acute or chronic rejection, also contributes to RAS stimulation. In cardiac transplant recipients, several haemodynamic parameters, abnormal cardiorenal neuroendocrine reflex mechanism and other hormonal systems (ANF, AVP, catecholamines) stimulate the RAS.