1. Results in 80 patients with primary aldosteronism (70 with tumour, 10 with hyperplasia) who underwent stimulation and suppression tests were analysed to assess the usefulness of several screening techniques. 2. On normal dietary sodium, normokalaemia was found in 27.5% of patients; 12.5% remained so despite 3 days of salt loading. Suppressed plasma renin activity (PRA: less than 1.43 pmol/l after stimulated conditions) gave a false-negative rate of 36%. Thus sole reliance on either hypokalaemia (serum potassium less than 3.5 mmol/l) or suppressed PRA as primary screening tests would have overlooked about a third of the patients in this series. 3. The single best diagnostic test for primary aldosteronism was the measurement of aldosterone excretion rate after 3 days of salt loading. 4. An anomalous postural fall in plasma aldosterone concentration when present, coupled with adrenal venous sampling, provided the best indicators of the presence of an aldosterone-producing adenoma.
1. To investigate the non-angiotensin effects of converting enzyme inhibition, angiotensin II was infused intravenously at 30 ng/min for 9 days in conscious rats to produce moderate blood pressure elevation. One group was given captopril (SQ 14 225) by gavage (100 mg/kg twice daily) and the other glucose. 2. After 7 days of captopril administration, enzyme blockade was confirmed by a tenfold greater depressor sensitivity to exogenous bradykinin and a markedly decreased plasma angiotensin converting enzyme activity. 3. Mean arterial pressure, heart rate and plasma renin activity were not different between captopril and glucose-treated groups in the presence of angiotensin II. Metabolic studies also revealed no long-term differences in water and food intake, weight change or sodium and potassium metabolism. 4. These findings suggest that, in the presence of angiotensin II, there is no detectable haemodynamic or metabolic effect of converting enzyme inhibition in rats and, therefore, that bradykinin plays little or no role in its long-term antihypertensive action.