Effects of Angiotensin I upon the Synthesis of Aldosterone

The effects of angiotensin I upon synthesis of aldosterone, corticosterone and cortisol were examined by incubation of beef adrenal tissue slices under the three different conditions. In the first experiment adrenal tissue slices were incubated with 2 and 10 μg/g tissue of angiotensin I. Both 2 and 10 μg/g tissue of angiotensin I stimulated the synthesis of aldosterone, corticosterone and cortisol significantly. However, during the incubation 70 to 75% of angiotensin I was converted to angiotensin II. In the second experiment 2. 6mM of EDTA and 3. 4mM of 8 hydroxyquinoline were added to prevent the conversion of angiotensin I to angiotensin II. Although the conversion was prevented, EDTA and 8 hydroxyquinoline made adrenal cells inactive to the stimulation of angiotensin I and II. In the third experiment adrenal slices were incubated with angiotensin I for 15 minutes and after then EDTA and 8 hydroxyquinoline were added. Ten μg/g tissue of angiotensin I stimulated aldosterone and corticosterone significantly. During the incubation about 25% of angiotensin II was converted to angiotensin II, but this converted amount of angiotensin II was not effective to stimulate the synthesis of aldosterone and corticosterone. From these results we can conclude that angiotensin I directly stimulates the synthesis of adrenocortical steroidogenesis as well as angiotensin II.