Stimulation of Corticosteroid Biosynthesis by Angiotensin I, [Des-Asp1] Angiotensin I? Angiotensin II and [Des-Asp1]Angiotensin II in Bovine Adrenal Fasciculata Cells R. HEPP, C. GRILLET, A. PEYTREMANN, AND M. B. VALLOTTON Division of Endocrinology, Department of Medicine, School of Medicine, University of Geneva, Geneva, Switzerland ABSTRACT. The effect of angiotensin I (AI), angiotensin II (All), [des-asp']AI, [des-asp']AII and [desasp'-arg2]AII on corticosteroid production in isolated fasciculata cells from bovine adrenals has been studied. All and [des-asp']AII in concentrations ranging from 10~9M to 10~6M had a potent stimulatory effect on steroid biosynthesis. The dose-response curves for both peptides were identical. AI was about 3 times less potent than All and [des-asp']AII. The effect of AI was not due to its conversion to All. [Des-asp']AI was as active as AI. No significant conversion to [des-asp']AII was observed. [Des-asp1argz]AII had only a minimal effect on steroidogenesis. The structural analog [sar1,-ala8]AII in-

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INCE Blair-West et al. first demonstrated that the 2-8 heptapeptide fragment of angiotensin II (All) stimulated aldosterone secretion in the sheep (1), several investigators have confirmed that [des-asp^angiotensin II is a potent stimulus of aldosterone biosynthesis both in vitro (2— 4) and in vivo (5-7). It has been suggested that [des-asp^AII is an important agonist in its own right with specific sites of action, mainly the adrenal glomerulosa cell, where its steroidogenic activity exceeds that of All (8). This prompted us to study the effect of [des-asp^AII and related peptides on adrenal fasciculata cells and to compare it with that of All. All has been shown to stimulate cortisol synthesis in the dog (911) and in the steer (12,13) as well as in isolated bovine fasciculata cells (14), where the effect appears to be mediated by cyclic AMP. In the present study, we compared

hibited all angiotensins specifically and competitively. The affinity of the cellular binding site was higher for All and [des-asp']AII than for [sar1,ala8]AII, but lower for AI and [des-asp']AI than for the inhibitor. Combination of submaximal doses of AI and All resulted in an additive effect on steroid production. By contrast, combination of maximal doses of both peptides had the same effect as All alone. These data demonstrate a potent steroidogenic activity for All as well as AI, [desasp']AI and [des-asp^AII in bovine adrenal fasciculata cells. A common receptor site for all four peptides is suggested. (Endocrinology 101: 717, 1977)

the steroidogenic activity of All with that of its precursor, angiotensin I (AI), and that of the angiotensin analogues [des-asp'jAI, [des-aspx]AII and [des-asp1-arg2]AII on isolated fasciculata cells from bovine adrenals. Our results demonstrate that all angiotensins tested except the hexapeptide fragment [des-asp1-arg2]AII have an important stimulatory effect on steroidogenesis in these cells. Materials and Methods Materials

[Ileu 5 ]Angiotensin I was obtained from Schwarz-Mann, Orangeburg, N.Y. [Asn'-val5]angiotensin II (Hypertensin®) and synthetic 1-24 ACTH (Synacthen®) were purchased from CIBA Pharmaceutical Products, Basle, Switzerland. The 2-10 nonapeptide ([des-asp']AI), the 2-8 heptapeptide ([des-asp']AII) and the 3-8 hexapeptide ([des-asp'-arg2]AII) analogues were a generous gift of Dr. F. M. Bumpus, Cleveland, Ohio. The source of [sar',ala8]AII was Received April 20, 1976. Supported by the Swiss National Science Founda- Eaton Laboratories, Norwich, N.Y. and was obtion grant No. 3.2300.74 and No. 4.7930.72. R.H. was tained through the courtesy of Dr. H. Brunner, supported by the Deutsche Forschungsgemeinschaft Lausanne. The converting enzyme inhibitor SQ 20'881 was kindly supplied by the Squibb and the Fondation Suisse de Cardiologie. 717

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HEPP ETAL.

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TABLE 1. Cross-reactivity of antisera to AI and to All

Neubauer hemocytometer cells in 0.9 ml.

Endo • 1977 Vol 101 • No 3

yielded about 106

Antiserum anti-AI angiotensin I [des-asp']angiotensin I angiotensin II [des-asp']angiotensin II [des-asp'-arg2]angiotensin II smaller fragments

anti-AI I

100 33

0 6

Stimulation of corticosteroid biosynthesis by angiotensin I [des-asp1]angiotensin I, angiotensin II and [des-asp1]-angiotensin II in bovine adrenal fasciculata cells.

Stimulation of Corticosteroid Biosynthesis by Angiotensin I, [Des-Asp1] Angiotensin I? Angiotensin II and [Des-Asp1]Angiotensin II in Bovine Adrenal F...
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