Summary
The effect of angiotensin II infusion on plasma pregnenolone, progesterone, corticosterone
and aldosterone was investigated in 4 cases of established hypoaldosteronism, in 4
elderly controls in the same age range and in 6 young normals. In young and old normals,
angiotensin II induced the expected dose response increase in aldosterone while corticosterone
usually decreased progressively during the infusion. Progesterone levels were not
significantly different in young and old subjects and no change was observed during
angiotensin II infusion. Baseline pregnenolone levels were significantly lower in
elderly controls and angiogensin II elicited a slight decrease in pregnenolone in
the two control groups. In selective hypoaldosteronism, baseline plasma aldosterone
concentrations were very low and the aldosterone response to angiotensin II was blunted.
Plasma corticosterone and progesterone levels were in a comparable range to normals
throughout the study. Contrary to control subjects, a dose dependant increase in pregnenolone
was observed during angiotensin II infusion in the patient group. These results suggest
that the anomalies of steroid biosynthesis found in selective hypoaldosteronism could
be contributing factors to the hypoaldosteronism in some patients.
Key-Words:
Hypoaldosteronism
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Angiotensin II
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Aldosterone
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Corticosterone
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Pregnenolone
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Progesterone
