Increased steroidogenesis by rat zona glomerulosa cells with increased cell concentration in vitro: evidence for a novel aldosterone-stimulating factor and implications regarding aldosterone biosynthesis

1982 ◽  
Vol 94 (2) ◽  
pp. 225-241 ◽  
Author(s):  
D. J. Campbell
Keyword(s):  
Incubation Medium ◽  
Cell Concentration ◽  
Zona Glomerulosa ◽  
Bicarbonate Buffer ◽  
Fourfold Increase ◽  
Aldosterone Production ◽  
Glomerulosa Cells ◽  
Stimulating Factor ◽  
Zona Glomerulosa Cells

A fourfold increase in the concentration of rat zona glomerulosa cells incubated in Krebs–Ringer bicarbonate buffer (KRBGA) increased aldosterone production per cell twofold. This cell concentration associated (CCA) increase in aldosterone production showed a dose–response relationship with the number of cells per incubation and was further increased in modified Medium 199, compared with KRBGA. The combination of a fourfold increase in cell concentration with each of maximally steroidogenic concentrations of K+, angiotensin II, ACTH, 5-hydroxytryptamine or cyclic AMP produced an increase in aldosterone production greater than that predicted from the algebraic sum of the steroidogenic effects of the factors acting separately. The CCA increase in basal aldosterone production was maximal during the first 30 min of incubation, could not be accounted for by accumulation of corticosterone in the incubation medium and was largely or completely abolished by the addition of pregnenolone, progesterone, deoxycorticosterone or corticosterone to the incubation medium. Together, these data support the proposal that the CCA effect was due to a novel aldosterone-stimulating factor which increased aldosterone production by stimulating pregnenolone formation. The aldosterone and corticosterone responses to exogenous pregnenolone, progesterone, deoxycorticosterone and corticosterone demonstrated that aldosterone and corticosterone production by zona glomerulosa cells in vitro may represent separate biosynthetic pathways. Furthermore, these studies provided evidence for a mechanism by which increased levels of exogenous pregnenolone, progesterone and deoxycorticosterone were able to increase their per cent conversion to aldosterone, but not to corticosterone.

Effect of composition of incubation medium on aldosterone and corticosterone production by isolated rat zona glomerulosa cells

1982 ◽  
Vol 94 (2) ◽  
pp. 211-224 ◽  
Author(s):  
D. J. Campbell
Keyword(s):  
Angiotensin Ii ◽  
Cyclic Amp ◽  
Incubation Medium ◽  
Zona Glomerulosa ◽  
Bicarbonate Buffer ◽  
Angiotensin Ii Antagonist ◽  
Aldosterone Production ◽  
Glomerulosa Cells ◽  
Zona Glomerulosa Cells

The role of the composition of the incubation medium in determining the steroidogenic responsiveness of collagenase-dispersed rat zona glomerulosa cells was examined by studying the effect on production of aldosterone and corticosterone of (1) changes in the bovine serum albumin (BSA) concentration in Krebs–Ringer bicarbonate buffer (KRBGA), (2) dialysis of the BSA and (3) comparison of KRBGA with 'modified' Medium 199. Medium 199 was modified so that its electrolytic content was identical to that of KRBGA. Compared with 0·1–0·2% BSA in KRBGA, BSA concentrations of 0·5 and 4% caused inhibition of both basal and K+-stimulated, but not angiotensin II-stimulated steroidogenesis. This inhibitory property of BSA was not removed by dialysis. The BSA did, however, contain a dialysable factor which increased both basal steroidogenesis and the steroidogenic response to maximal K+ and angiotensin II stimulation. Both incubation media contained 0·2% BSA for the comparison of KRBGA with modified Medium 199. Modified Medium 199 increased both basal steroidogenesis and the aldosterone response to K+ stimulation (per cent increase above basal) by two- to threefold compared with KRBGA, with smaller increases in the response to ACTH and 5-hydroxytryptamine (5-HT) and a decrease in the response to cyclic AMP. In contrast, modified Medium 199 increased the aldosterone response to angiotensin II by sevenfold, from 60% (in KRBGA) to 420%. In KRBGA, angiotensin II inhibited K+-stimulated aldosterone production. This effect was produced by concentrations of angiotensin II below the threshold for steroidogenesis and could be reproduced with the angiotensin II antagonist [Sar1, Ileu8]-angiotensin II. Angiotensin II did not inhibit K+-stimulated aldosterone production in modified Medium 199. These data emphasize the importance of the composition of the incubation medium in determining the steroidogenic responsiveness of rat zona glomerulosa cells in vitro. Furthermore, these data indicate that the steroidogenic response to angiotensin II, compared with K+, ACTH, 5-HT and cyclic AMP, is more readily influenced by other, as yet unidentified, factors in the incubation medium, and are consistent with recent evidence that angiotensin II and K+ do not share a common mode of action on steroidogenesis by these cells.

Inhibition of aldosterone release by hypoxia in vitro: interaction with carbon monoxide

1994 ◽  
Vol 76 (2) ◽  
pp. 689-693 ◽  
Author(s):  
H. Raff ◽  
B. Jankowski
Keyword(s):  
Carbon Monoxide ◽  
Angiotensin Ii ◽  
Zona Glomerulosa ◽  
Michaelis Constant ◽  
Aldosterone Synthase ◽  
Aldosterone Production ◽  
Glomerulosa Cells ◽  
In Vitro Interaction ◽  
Zona Glomerulosa Cells

We have demonstrated that the aldosteronogenic pathway of the zona glomerulosa is unusually sensitive to modest changes in PO2 (Michaelis constant for O2 approximately 95 Torr). The current study evaluated the interaction of CO (the classic ligand for P-450 enzymes) and the decreases in O2 on aldosteronogenesis in vitro. Bovine adrenocortical zona glomerulosa cells were incubated for 2 h and stimulated with either adenosine 3′,5′-cyclic monophosphate (cAMP) or angiotensin II. Ten and 20% CO led to significant decreases in cAMP- and angiotensin II-stimulated aldosteronogenesis. The combination of 20% CO and moderate decreases in PO2 (from approximately 140 to approximately 100 Torr) led to an interactive decrease in aldosterone production. The conversion of corticosterone to aldosterone catalyzed by aldosterone synthase, which is the site of O2 sensitivity, was not significantly inhibited by CO. We conclude that the aldosterone pathway is not exceptionally sensitive to CO compared with other steroidogenic pathways. This observation suggests that the unique O2-sensitive properties of the aldosterone pathway located primarily within aldosterone synthase may not reside in its CO binding site (i.e., heme).

Effect of exposure to hypoxia from birth on aldosterone in rabbits: role of unesterified fatty acids

1997 ◽  
Vol 272 (4) ◽  
pp. R1084-R1087 ◽  
Author(s):  
H. Raff ◽  
B. M. Jankowski ◽  
T. L. Goodfriend ◽  
J. E. Baker ◽  
P. E. Papanek
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Zona Glomerulosa ◽  
Hypoxic Hypoxia ◽  
Adrenocortical Function ◽  
Total Serum ◽  
Aldosterone Production ◽  
Glomerulosa Cells ◽  
Zona Glomerulosa Cells

Hypoxia and fluid and electrolyte disturbances are serious risks to normal postnatal development. Because a decrease in inspired O2 (hypoxic hypoxia) inhibits aldosterone synthesis in the adult and aldosterone controls water and electrolyte balance, we studied adrenocortical function in rabbits exposed to normobaric normoxia or hypoxic hypoxia (fraction of inspired O2 0.09) from birth. At 21 days of age, rabbits were anesthetized, the adrenals were rapidly removed, and the adrenal capsules containing mostly zona glomerulosa cells were separated. Cells were dispersed with collagenase and studied in vitro. Hypoxia in vivo resulted in a 73% decrease in basal aldosterone release and a 86% decrease in adenosine 3',5'-cyclic monophosphate-stimulated aldosterone release in vitro. We hypothesized that increased unesterified fatty acids could be partly responsible for inhibition of aldosterone synthesis. Total serum unesterified fatty acids in hypoxic kits were significantly increased (298 +/- 14 micromol/l) compared with normoxic kits (184 +/- 31 micromol/l). When cells from hypoxic rabbits were washed with fatty acid-free albumin and studied under conditions devoid of fatty acids, aldosterone production was partially restored. Corticosterone production was not affected by washing. Washing had no effect on aldosterone synthesis by cells from normoxic rats. Finally, exposing washed zona glomerulosa cells to oleic acid (10-50 microM) inhibited aldosteronogenesis. We conclude that exposure to hypoxia from birth attenuates aldosterone production in part due to an increase in levels of unesterified fatty acid levels.

Biosynthetic and morphological evidence for inhibition of aldosterone production following administration of ACTH to sheep

1980 ◽  
Vol 94 (4) ◽  
pp. 559-570 ◽  
Author(s):  
John G. McDougal ◽  
Aldona Butkus ◽  
John P. Coghlan ◽  
Derek A. Denton ◽  
Jürg Müller ◽  
...  
Keyword(s):  
Time Course ◽  
Cell Number ◽  
Zona Glomerulosa ◽  
Morphological Evidence ◽  
Zona Fasciculata ◽  
Aldosterone Production ◽  
Glomerulosa Cells ◽  
17 Hydroxyprogesterone ◽  
Zona Glomerulosa Cells

Abstract. The effect of ACTH administration for 1—5 days on the morphology and steroidogenic capability of sheep adrenal tissue has been examined. During this period of treatment there was a gradual decline in the in vitro conversion of 3H-labelled precursors to products of solely zona glomerulosa origin (aldosterone and 18-hydroxycorticosterone) while conversion to products of zona fasciculata origin (17-hydroxyprogesterone, 11-deoxycortisol and cortisol) was stimulated throughout. Conversion to DOC, 18-hydroxydeoxycorticosterone and corticosterone (steroids produced by both the zona glomerulosa and the zona fasciculata) declined after initial stimulation. Within 2—3 days of the commencement of treatment, the zona glomerulosa showed a progressive decrease in cell number associated with disruption of cords and cell separation. Ultrastructurally, it was found that typical zona glomerulosa cells had almost disappeared. The majority of residual cells in this area had a structure intermediate between zona glomerulosa and zona fasciculata cells. The similarity in time-course of the alterations in both the morphological and biosynthetic characteristics suggests that the decline in aldosterone output caused by ACTH administration to sheep results from the loss of adrenal zona glomerulosa cells, predominantly due to selective cellular degeneration.

effects of insulin on aldosterone production in rat zona glomerulosa cells

Life Sciences ◽  
1992 ◽  
Vol 50 (23) ◽  
pp. 1781-1787 ◽  
Author(s):  
Dan Petrasek ◽  
Gerard Jensen ◽  
Michael Tuck ◽  
Naftali Stern
Keyword(s):  
Zona Glomerulosa ◽  
Aldosterone Production ◽  
Glomerulosa Cells ◽  
Zona Glomerulosa Cells
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