The present studies were conducted in patients with primary aldosteronism (PA) before and during more than 3 months of spironolactone (SPL) treatment and essential hypertension (EHT) to evaluate the effects of SPL on aldosterone secretion. All patients were hospitalized and received a furosemide test and angiotensin II infusion test (Ang II test) under the sodium restricted diet.
Furosemide significantly increased both plasma renin activity (PRA) and plasma aldosterone concentration (PAC) in EHT, while neither PRA nor PAC responded to the furosemide in untreated PA. In contrast, furosemide significantly increased both PRA and PAC in PA given SPL (PAC : 345.6±55.8 to 492.7±76.8 pg/ml, p<0.05, mean±SE ; PRA : 2.60±0.80 to 7.00±2.00 ng/ml/hr, p<0.05).
On the other hand, angiotensin II (Ang II) infusion induced a dose-dependent increase in PAC and a decrease in PRA in EHT. Although PAC and PRA did not respond to Ang II in untreated PA, dose-dependent increase was observed when Ang II was administered to SPL treated PA. Thus, aldosterone secretion is dependent mainly on ACTH in untreated PA, while it is more strongly regulated by the renin-angiotensin-system than ACTH after SPL.
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