The diagnostic and therapeutic uses of saralasin in renal transplant hypertension.

Saralasin was used as a functional test of the renin-angiotensin axis in 4 renal transplant patients with hypertension. Blood pressure was recorded by an automatic recording device and plasma renin activity was measured by radioimmunoassay of angiotensin I. A positive saralasin test suggested renin-mediated hypertension despite normal peripheral renin levels in a 40-year-old man whose original kidney disease was nephrosclerosis. Since the blood pressure was refractory to intravenous sodium nitroprusside saralasin was used for 14 hours to control blood pressure before and after arteriography in the patient. Removal of the native kidneys markedly ameliorated the hypertension. A 35-year-old woman with transplant hypertension was responsive to angiotensin blockade only during a period of abrupt worsening of blood pressure associated with an acute rejection episode. Finally, 2 patients with advanced chronic rejection responded to saralasin administration. These studies confirm that 1) angiotensin blockade is a useful tool in the diagnosis of renin-dependent hypertension even when plasma renin levels are not elevated, 2) saralasin can be used to control renin-dependent forms of hypertension that are refractory to intravenous sodium nitroprusside therapy and 3) transplant hypertension associated with acute and chronic rejection appears to be renin-dependent.