CHRONIC ANGIOTENSIN-CONVERTING ENZYME-INHIBITION MAY IMPROVE SODIUM-EXCRETION IN CARDIAC TRANSPLANT HYPERTENSION

Cyclosporine-associated hypertension (CAH) may be mediated in part by sodium and volume retention, To investigate this issue, we studied the effects of a calcium antagonist, nitrendipine (NIT, 10-20 mg b.i.d.), and a converting enzyme inhibitor, lisinopril (LIS, 10-20 mg o.d.), o n blood pressure (office BP, 24 hr ambulatory BP), excretion of an acu te sodium load (200 mmol/2 hr i.v.), glomerular filtration rate (inuli n clearance), cumulative dopamine excretion, plasma atrial natriuretic peptide (ANP), and endothelin excretion in 8 patients with CAH after cardiac transplantation in a double-blind, randomized, crossover trial for 6 weeks. Five patients received a diuretic during the trial at a constant dose. Office diastolic BP (DBP) decreased significantly with LIS from 97+/-6 to 87+/- 9 mmHg and with MT from 96+/-7 to 92+/-12 mmH g. Ambulatory 24 hr DBP decreased significantly from 96+/- 7 mmHg to 8 6+/-10 mmHg (LIS) and to 84+/-11 mmHg (NIT). Ambulatory DBP during the day was lowered significantly from 98+/-11 mmHg to 87+/-10 mmHg (LIS) and to 88+/-9 mmHg (MT) and during the night from 95+/-9 mmHg to 86+/ -8 mmHg (LIS) and to 79+/-7 mmHg (NIT). Cumulative sodium excretion 6 hr after an acute sodium load increased to 52+/-39 mmol (placebo), 96/-44 mmol (LIS, P<0.05 vs. placebo), and 71+/-34 mmol (NIT). Glomerula r filtration rate, cumulative dopamine excretion, ANP, and endothelin excretion did not differ between either treatment group. We conclude, that: (1) both drugs were similar in lowering office BP and during the day, but NIT tended to be more effective during the night; and (2) cu mulative sodium excretion during LIS was significantly increased compa red with placebo. There was a similar trend during NIT also. Therefore , it is possible that chronic angiotensin-converting enzyme inhibition and possibly calcium antagonists might improve the sodium-retaining s tate in CAH independent of differences in blood pressure, ANP, dopamin e, or renal function.