FURTHER STUDIES ON THE STIMULATION OF RAT ADRENAL CAPSULAR CELLS: FOUR TYPES OF RESPONSE

1980 ◽  
Vol 87 (1) ◽  
pp. 11-27 ◽  
Author(s):  
J. F. TAIT ◽  
S. A. S. TAIT ◽  
J. B. G. BELL ◽  
P. J. HYATT ◽  
B. C. WILLIAMS
Keyword(s):  
Angiotensin Ii ◽  
Free Acid ◽  
Zona Glomerulosa ◽  
Maximum Response ◽  
Maximal Response ◽  
Zona Fasciculata ◽  
Similar Response ◽  
Response Characteristics ◽  
High Concentrations ◽  
Stimulation Of

Preparations of capsular rat adrenal cells consisting mainly of zona glomerulosa with less than 5% zona fasciculata contamination are described. The responses of the aldosterone and corticosterone outputs of these preparations to various stimuli were of four types. (1) Variations in K+ concentration gave a maximum aldosterone response at 5·9–8·4 mm-K+, about sixfold greater than the control output at 3·6 mmol/l. At higher K+ concentrations, such as 13 mmol/l, the response decreased. (2) Serotonin (at a concentration of about 10−4 mol/l) gave only a slightly lower maximal aldosterone response than did K+ but this did not decrease significantly at higher concentrations. Serotonin gave significant steroidogenic response at 10−8 mol/l. (3) [Asp1,Val5]-Angiotensin II (10−10 mol/l) with 3·6 mm-K+ gave a significant response and a constant maximal response at 2·5 × 10−8 mol/l. This maximum response was about half that found for both aldosterone and corticosterone when stimulated maximally by K+ or serotonin: [des-Asp1,Ile5]- and [des-Asp1,Val5]-angiotensin II (angiotensin III) gave similar response characteristics but had a lower potency in this cell preparation. The initial maximum response could be further increased at a higher concentration (from 2·5 × 10−5 mol/l) of a preparation of [Asn1,Val5]-amide angiotensin II (Hypertensin-Ciba) and might eventually be greater than with K+. This additional response was, to a major extent, due to stimulation of the contaminating zona fasciculata cells and was not seen with high concentrations of the free acid, angiotensin II. It was also not seen in two experiments with pure [Asn1]-amide angiotensin II and therefore it could have been due to some impurity in Hypertensin-Ciba. (4) Adrenocorticotrophin (Synacthen) at 3 × 10−11 mol/l gave a significant steroidogenic response. Higher concentrations (3 × 10−10 to 7·5 × 10−9 mol/l) gave no constant maximum but the response could be much greater than for other stimuli such as K+, serotonin and [Asp1]-angiotensin II. This additional response was again due to steroid precursors, e.g. deoxycorticosterone and corticosterone from contaminating zona fasciculata cells. Similar results were obtained with ACTH (ACTHAR) in three experiments. Threshold sensitivity (a significant increase in steroidogenesis) for ACTH (Synacthen) was, in two experiments, greater for zona fasciculata-reticularis cells (3 × 10−12 mol/l) than for zona glomerulosa cells (3 × 10−11 mol/l). The data show that aldosterone output was approximately a function of the square of the corresponding corticosterone value. Specific effects on this pathway can be shown by values of aldosterone/corticosterone2 greater than one. Of all stimuli used, only K+ concentrations of 5·3, 5·9 and 13 mmol/l gave such effects. However, because of several considerations, only positive results with other stimuli may be meaningful. Calculation of this parameter might be useful as a screening test in bioassays for substances with aldosterone-stimulating activity.

The properties of adrenal zona glomerulosa cells after purification by gravitational sedimentation

1974 ◽  
Vol 185 (1081) ◽  
pp. 375-407 ◽  
Keyword(s):  
Angiotensin Ii ◽  
Cyclic Amp ◽  
Microscopic Examination ◽  
Zona Glomerulosa ◽  
Maximal Response ◽  
Zona Fasciculata ◽  
Gravitational Sedimentation ◽  
Rat Adrenals ◽  
Glomerulosa Cells ◽  
Zona Glomerulosa Cells

The densities of latex spheres and biological cells can be reliably determined from their sedimentation rate in an albumin gradient under unit gravitational force. The densities of zona glomerulosa and fasciculata cells of rat adrenals were found to be 1.072 ± 0.004 and 1.040 ± 0.001 respectively. Purified zona glomerulosa cells of rat adrenals can be prepared by gravitational sedimentation of dispersed cells from capsule strippings of the gland, which originally contain 3 to10% zona fasciculata contamination. Electron and phase microscopic examination of the sedimented glomerulosa cells and their steroidogenic response to ACTH and cyclic AMP indicate that they are reasonably free of contamination from zona fasciculata cells. Electron microscopic examination of the purified glomerulosa cells indicates that most of them are reasonably normal in structure. Their basal production of corticosterone is decreased after sedimentation. However, their maximal response of corticosterone output to serotonin and potassium and their response to all potassium concentrations is not significantly altered, indicating normal function for the cells producing steroids. Their maximal responses to ACTH, valine angiotensin II and cyclic AMP are decreased, but, at the doses used, steroidogenesis by the zona fasciculata contamination in the unfractionated preparation would be stimulated by these substances. Purified zona glomerulosa cells have about the same maximal response of corticosterone output (about twofold) to potassium, valine and isoleucine angiotensin II, serotonin and ACTH. The maximal response of the purified zona glomerulosa cells to cyclic AMP is similar to that elicited by valine and isoleucine angiotensin II, potassium, serotonin or ACTH. This indicates that if these stimuli act by increasing cyclic AMP output, then the maximal response of corticosterone output (about twofold) is defined by the limited response of the biosynthetic pathways to cyclic AMP.

Effects of α-melanocyte-stimulating hormone on the cyclic AMP and phospholipid metabolism of rat adrenocortical cells

1986 ◽  
Vol 110 (3) ◽  
pp. 405-416 ◽  
Author(s):  
P. J. Hyatt ◽  
J. B. G. Bell ◽  
K. Bhatt ◽  
F. W. Chu ◽  
J. F. Tait ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Cyclic Amp ◽  
Phosphatidic Acid ◽  
Inositol Phosphates ◽  
Phospholipid Metabolism ◽  
Zona Glomerulosa ◽  
Zona Fasciculata ◽  
Additional Increase ◽  
Glomerulosa Cells ◽  
Stimulation Of

ABSTRACT Results on the effects of peptides on the phospholipid metabolism and steroid and cyclic AMP (cAMP) outputs of rat adrenal capsular cells (96% zona glomerulosa, 4% zona fasciculata) were obtained in a series of three batch experiments. Their significance was examined by analysis of variance. Incorporation of [32P] into phosphatidylcholine, phosphatidic acid and phosphatidylinositol was measured. Production of [3H]inositol-1 monophosphate, inositol-1,4 bis-phosphate and inositol-1,4,5 tris-phosphate was estimated after prelabelling with [3H]inositol followed by 1 min incubation with a steroidogenic stimulus. Angiotensin II (0·25 nmol/l to 0·25 μmol/l) highly significantly (P < 0·01) stimulated aldosterone and corticosterone outputs, [32P] incorporation into phosphatidic acid and phosphatidylinositol (but not into phosphatidylcholine) and the production of the three [3H]inositol phosphates. Aldosterone and corticosterone outputs were stimulated by α-MSH (above 0·1 nmol/l). However, incorporation of [32P] was not significantly increased until 10 μmol α-MSH/l but, unlike with angiotensin II, incorporation into phosphatidylcholine was also then stimulated. Also, the production of the inositol phosphates was not increased significantly (P > 0·05) by any dose of α-MSH (10 nmol/l, 1 μmol/l and 0·1 mmol/l) used. Therefore, it can be concluded that α-MSH does not stimulate phospholipase C in rat zona glomerulosa cells. In further experiments, it was also found that there were significant increases in cAMP as well as in steroid outputs above 1 nmol α-MSH/l (highly significant above 10 nmol α-MSH/l). There were plateaux of the outputs of both steroids and cAMP from 0·1 to 1 μmol α-MSH/l. However, there were further increases in steroid and cAMP outputs of the capsular cells at higher doses. Concomitant results on the stimulation of corticosterone output by zona fasciculata–reticularis cells indicate that this additional increase was mostly due to the stimulation of the contaminating zona fasciculata cells. It was also confirmed that α-MSH preferentially stimulates steroidogenesis by the zona glomerulosa. However, under our conditions, α-MSH highly significantly increased the output of cAMP by both zona fasciculata and glomerulosa cells. J. Endocr. (1986) 110, 405–416

Effects of angiotensin II and ACTH on normal and tumourous human adrenocortical cells

1983 ◽  
Vol 104 (1) ◽  
pp. 103-109 ◽  
Author(s):  
Wolfgang Belmega ◽  
Wolfgang Oelkers ◽  
Lutz Belkien ◽  
Monika Shirpai ◽  
Ulrich Fiedler ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Renin Angiotensin System ◽  
Zona Glomerulosa ◽  
Zona Fasciculata ◽  
Adrenocortical Adenoma ◽  
Response Curves ◽  
Adrenocortical Cells ◽  
Normal Cells ◽  
Fold Stimulation

Abstract. Isolated adrenocortical cells from 6 patients with a 'normal' zona fasciculata, 4 patients with a 'normal' zona glomerulosa, and tumour cells from 1 adrenocortical adenoma and 1 carcinoma were incubated with and without increasing concentrations of ACTH 1–24 (10−13 m to 10−9 m) or Asp1-Ile5-angiotensin II (10−11 m to 10−7 m). In 4/5 'normal' cases, cortisol was clearly stimulated by 10−13 m ACTH. The maximum of the dose-response curve (5-fold stimulation) was reached at 10−10 m ACTH. Angiotensin II (All) started to stimulate 'normal' cells at 10−11 m with a maximum (2-fold stimulation) at 10−9 m. Aldosterone production by 'normal' cells was less markedly stimulated by ACTH and All, although the threshold doses for both peptides were similar to those of the cortisol response curves. The cells of the adrenocortical adenoma from a patient with Cushing's syndrome produced large amounts of cortisol and small amounts of aldosterone, both steroids being clearly stimulated by ACTH and AII. The adrenocortical carcinoma cells produced small amounts of cortisol and no aldosterone. Cortisol production responded to ACTH, but not to AII. The results suggest that an activated renin-angiotensin system may stimulate the zona fasciculata, since 10−11 m All (= 10 pg AII/ml) is a normal plasma All concentration on an unrestricted diet. Clinical evidence supporting this thesis is reviewed. However, cortisol production itself will rarely be increased by All in vivo, since a downregulation of ACTH would occur.

Stimulation of aldosterone biosynthesis by sodium sequestration: role of angiotensin II

1982 ◽  
Vol 243 (6) ◽  
pp. E450-E457
Author(s):  
J. Muller ◽  
E. G. Lund ◽  
L. Hofstetter ◽  
D. B. Brunner ◽  
P. Haldy
Keyword(s):  
Angiotensin Ii ◽  
Enzyme Inhibitor ◽  
Zona Glomerulosa ◽  
High Dose ◽  
Converting Enzyme ◽  
Bilateral Nephrectomy ◽  
Stimulatory Action ◽  
Sodium Sequestration ◽  
Stimulation Of

The role of angiotensin II in the stimulation of aldosterone biosynthesis by sodium sequestration in potassium-deficient rats was assessed by experiments involving 1-day angiotensin II infusion, converting enzyme inhibition, and bilateral nephrectomy. In intact rats, only an extremely high dose of exogenous angiotensin II imitated the stimulatory effects of polyethylene glycol-induced edema on the conversions of deoxycorticosterone and corticosterone to 18-hydroxycorticosterone and aldosterone. Treatment with the converting enzyme inhibitor captopril as well as bilateral nephrectomy blocked the aldosterone-stimulating action of edema. This inhibition was prevented by the simultaneous infusion of angiotensin II in captopril-treated rats but not in nephrectomized animals. According to these results, angiotensin II is an essential mediator in the stimulation of aldosterone biosynthesis by sodium sequestration. However, the role of the kidneys appears to be twofold. First, they act through the secretion of renin. In addition, a second yet unknown kidney factor is necessary for a full response of the zona glomerulosa to the stimulatory action of angiotensin II.

Electrical responses in cat adrenal cortex: possible relation to aldosterone secretion.

1979 ◽  
Vol 237 (2) ◽  
pp. E158 ◽  
Author(s):  
E Natke ◽  
E Kabela
Keyword(s):  
Membrane Potential ◽  
Angiotensin Ii ◽  
Adrenal Cortex ◽  
Adrenal Glands ◽  
Membrane Depolarization ◽  
Zona Glomerulosa ◽  
Membrane Potentials ◽  
Zona Fasciculata ◽  
Aldosterone Secretion ◽  
Stimulus Secretion Coupling

The effects of secretagogues for aldosterone release were studied on the membrane potential of cells in the adrenal cortex of the cat. Adrenal glands were excised, sliced, and continuously superfused. Membrane potentials were recorded from both zona glomerulosa and zona fasciculata-reticularis. Secretagogues, angiotensin II (1 microgram/ml) and 20 mM KCl, were found to depolarize cells rapidly. Ouabain (10(-5) M) also depolarized the membrane potential although the response was sluggish. Samples of the superfusate were collected and analyzed by radioimmunoassay for their aldosterone and cortisol content. Depolarizing concentrations of angiotensin II, KCl, and ouabain seemed to increase aldosterone release. Cortisol output was more variable. Saralasin blocked the effects of angiotensin II on the membrane potential. These experiments suggest that membrane depolarization plays a role in the stimulus-secretion coupling of mineral corticoids.

Potentiation of Adrenaline-Induced Platelet Aggregation by Angiotensin II

1985 ◽  
Vol 54 (03) ◽  
pp. 717-720 ◽  
Author(s):  
Yu-An Ding ◽  
D Euan MacIntyre ◽  
Christopher J Kenyon ◽  
Peter F Semple
Keyword(s):  
Platelet Aggregation ◽  
Angiotensin Ii ◽  
Human Platelet ◽  
Inhibitory Effect ◽  
Facilitatory Effect ◽  
Ang Ii ◽  
Human Platelet Aggregation ◽  
Low Concentrations ◽  
High Concentrations ◽  
Stimulation Of

SummaryThe effects of angiotensin II (ANG II) alone and in combination with other agonists on human platelet aggregation, thromboxane B2 (TxB2) and cytosolic [Ca2+]i were investigated. ANG II (10™11 - 10™7 M) alone had no direct effect on aggregation, TxB2 production or [Ca2+]i after short- (<2 min) or longterm (30 min) incubation. In contrast, low concentrations of ANG II (10™11 M) enhanced adrenaline-induced platelet aggregation but high concentrations (10™7 M) had an inhibitory effect. Moreover, ANG II (10™11 - 10™7 M) augmented platelet responses to the TxA2 mimetic, U44069. Pretreatment of platelets with flurbiprofen abolished this facilitatory effect of ANG II on adrenaline- but not on U44069-induced platelet aggregation. These results suggest that ANG II stimulation of agonist-induced platelet activation may be due to potentiation of the effects rather than the synthesis of TxA2

Long-term effects of ACTH combined with angiotensin II on steroidogenesis and adrenal zona glomerulosa morphology in the rat

1987 ◽  
Vol 114 (1) ◽  
pp. 47-54 ◽  
Author(s):  
Anne M. Riondel ◽  
Piera Rebuffat ◽  
Giuseppina Mazzochi ◽  
Gastone G. Nussdorfer ◽  
Rolf C. Gaillard ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Morphological Changes ◽  
Zona Glomerulosa ◽  
Zona Fasciculata ◽  
Homogeneous Population ◽  
Long Term Treatment ◽  
Acth Treatment ◽  
Glomerulosa Cells ◽  
Zona Glomerulosa Cells

Abstract. To test the hypothesis that the trophic action of angiotensin II on the adrenal zona glomerulosa may allow a sustained stimulation of aldosterone by ACTH by preventing the morphological changes of the zona glomerulosa cells into zona fasciculata-like elements we investigated the effects in rats of a 6-day treatment with ACTH (100 μg/kg/day) alone or combined with angiotensin II (300 ng/kg/day) on corticosterone and aldosterone production and adrenal morphology. The responsiveness of both steroids to an acute ACTH dose was also studied on the last day of long-term treatment. Morphologic data showed that prolonged ACTH treatment stimulated the growth of zona glomerulosa cells, though it transformed the tubulo-lamellar cristae of mitochondria into a homogeneous population of vesicles. Angiotensin II furthered the trophic effects of ACTH but prevented the mitochondrial transformation. Despite its ability to conserve the well differentiated aspect of the zona glomerulosa cells, the administration of angiotensin II was unable to prevent the fall in the secretion of aldosterone caused by chronic ACTH treatment and its subsequent unresponsiveness to ACTH stimulation.

Selective Hypoaldosteronism: A Study of Steroid Biosynthetic Pathways under Adrenocorticotrophin and Angiotensin II Infusion

1976 ◽  
Vol 51 (s3) ◽  
pp. 335s-337s ◽  
Author(s):  
M. Lebel ◽  
J. H. Grose
Keyword(s):  
Angiotensin Ii ◽  
Zona Glomerulosa ◽  
Plasma Aldosterone ◽  
Zona Fasciculata ◽  
Biosynthetic Pathways ◽  
Normal Functioning ◽  
Probable Consequence ◽  
Plasma Steroids ◽  
Dose Dependent Increase ◽  
Dose Dependent

1. The functional integrity of the adrenal cortex has been tested in a case of selective hypoaldosteronism by adrenocorticotrophin (ACTH) and angiotensin II (AII) infusion. 2. During ACTH infusion a normal functioning zona fasciculata was indicated by the impressive increase of the ACTH-dependent plasma steroids; the aldosterone response was moderate. 3. During AII infusion the plasma aldosterone response was blunted with an unexpected dose-dependent increase in pregnenolone, resulting in abnormal decreasing progesterone/pregnenolone ratios during the infusion, suggesting a slow-down in the conversion of pregnenolone into progesterone. 4. This defect, a probable consequence of chronic renin deficiency on the zona glomerulosa, could be a contributing factor to the hypoaldosteronism.

Mechanisms of ET-1 potentiation of angiotensin II stimulation of aldosterone production

1993 ◽  
Vol 265 (2) ◽  
pp. E179-E183 ◽  
Author(s):  
E. N. Cozza ◽  
C. E. Gomez-Sanchez
Keyword(s):  
Angiotensin Ii ◽  
Zona Glomerulosa ◽  
Ang Ii ◽  
Aldosterone Secretion ◽  
Direct Stimulation ◽  
Potentiation Effect ◽  
Aldosterone Production ◽  
Glomerulosa Cells ◽  
Pkc Inhibitors ◽  
Stimulation Of

Endothelin-1 (ET-1) exerts the following two types of aldosterone-stimulating actions on glomerulosa cells: ET-1-mediated direct stimulation of aldosterone secretion (per se effect) and potentiation of the aldosterone secretion to angiotensin II (ANG II; potentiation effect). The role of Ca2+ and protein kinase C (PKC) systems in these two effects was investigated. Incubations of calf cultured adrenal zona glomerulosa cells in low-Ca2+ media or in the presence of the Ca2+ channel antagonist verapamil reduced the aldosterone secretion to ET-1. When cells were preincubated with ET-1 in a low-Ca2+ media or in the presence of the Ca2+ channel antagonist verapamil, washed, and incubated in media with normal Ca2+, ANG II showed potentiation of ANG II-stimulated aldosterone secretion. The PKC inhibitors H-7 and staurosporine did not decrease ET-1-stimulated aldosterone secretion, but they inhibited the potentiation effect of ET-1 on ANG II-mediated aldosterone secretion. Adrenocorticotropic hormone desensitization or prolonged phorbol ester stimulation of PKC resulting in desensitization also resulted in the abolition of the ET-1-mediated ANG II potentiation of aldosterone secretion. The PKC inhibitors did not affect ANG II-stimulated aldosterone secretion. We conclude that ET-1 exerts a direct stimulation of aldosterone secretion through a mechanism dependent on Ca2+ and potentiates ANG II-mediated aldosterone stimulation through a mechanism involving PKC.

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