STUDIES ON CYCLIC NUCLEOTIDES IN THE ADRENAL GLAND

1979 ◽  
Vol 90 (1) ◽  
pp. 139-146 ◽  
Author(s):  
Sumio Shima ◽  
Yoshiko Kawashima ◽  
Masanao Hirai
Keyword(s):  
Cyclic Amp ◽  
Adrenal Cortex ◽  
Calcium Ionophore ◽  
Extracellular Calcium ◽  
Zona Fasciculata ◽  
Acth Stimulation ◽  
Steroid Production ◽  
Low Concentrations ◽  
Cyclic Amp Accumulation ◽  
High Concentrations

ABSTRACT Effects of ACTH and calcium on cyclic AMP and steroid production by the zona fasciculata-reticularis (the decapsulated fraction) from the rat adrenal cortex have been studied. Increasing concentrations of extracellular calcium enhanced the action of ACTH on cyclic AMP and steroid production. These effects of ACTH with calcium were prevented by lanthanum, but not by tetracaine or verapamil, suggesting that ACTH stimulation may be mediated by calcium through a process not involving the tetracaine- or verapamil-vulnerable step(s) of the calcium current. High concentrations of external calcium itself increased cyclic AMP accumulation without any increase in steroidogenesis. A calcium ionophore, X537A was stimulatory for steroidogenesis but inhibitory with respect to cyclic AMP accumulation. Considered together with the findings of steroidogenic stimulation by low concentrations of ACTH without cyclic AMP increase, these results suggest that ACTH primarily increases intracellular calcium mobilization thus stimulating directly the steroidogenesis, which is independent of the cyclic AMP system. Relatively high concentrations of ACTH activate the adenylate cyclase, which depends on extracellular calcium to increase cyclic AMP levels and stimulation of steroidogenesis by the decapsulated fractions of the adrenal cortex.

Hormone-stimulated glycogenolysis in isolated goldfish hepatocytes

1976 ◽  
Vol 231 (1) ◽  
pp. 191-197 ◽  
Author(s):  
MJ Birnbaum ◽  
J Schultz ◽  
JN Fain
Keyword(s):  
Cyclic Amp ◽  
Blocking Agent ◽  
Ionophore A23187 ◽  
Bacterial Collagenase ◽  
Goldfish Carassius Auratus ◽  
Low Concentrations ◽  
Cyclic Amp Accumulation ◽  
The Common ◽  
High Concentrations ◽  
Very High

Hepatocytes isolated from the liver of the common goldfish Carassius auratus L. with crude bacterial collagenase maintained ATP levels for at least 2 h. Glycogenolysis was maximally activated by 1 X 10(-6) M epinephrine and 5.8 X 10(-9) M glucagon. In liver cells incubated in calcium-free buffer containing 1 mM ethylene glycol-bis-(beta-aminoethylether)-N,N'-tetraacetic acid, basal glycogenolysis was enhanced by the addition of 1-4 mM calcium but the elevation of cyclic AMP and glycogenolysis due to epinephrine was unaffected by calcium. The divalent cation ionophore A23187 did not alter basal or hormone-stimulated glycogenolysis. Isoproterenol was approximately as potent as epinephrine but phenylephrine was glycogenolytic only at very high concentrations. l-Propranolol competitively inhibited the increased glycogenolysis due to catecholamines but phentolamine was ineffective as a blocking agent. Isoproterenol and epinephrine stimulated glycogenolysis at lower concentrations than those required to elevate cyclic AMP accumulation. Phenylephrine was without effect on cyclic AMP. Propranolol competitively inhibited both epinephrine- and isoproterenol-stimulated cyclic AMP accumulation, but phentolamine did not block either response. Catecholamine-stimulated glycogenolysis in goldfish liver is apparently a beta-adrenergic effect. However, low concentrations of epinephrine enhance glycogenolysis without affecting total cyclic AMP.

In Vitro Effects of Ethanol on Rabbit Platelet Aggregation, Secretion of Granule Contents, and Cyclic AMP Levels in the Presence of Prostacyclin

1989 ◽  
Vol 61 (02) ◽  
pp. 254-258 ◽  
Author(s):  
Margaret L Rand ◽  
Peter L Gross ◽  
Donna M Jakowec ◽  
Marian A Packham ◽  
J Fraser Mustard
Keyword(s):  
Cyclic Amp ◽  
Inhibitory Effect ◽  
Rabbit Platelet ◽  
Inhibitory Effects ◽  
Low Concentrations ◽  
Rabbit Platelets ◽  
High Concentrations ◽  
In Vitro Effects ◽  
Aggregation Of Platelets

SummaryEthanol, at physiologically tolerable concentrations, inhibits platelet responses to low concentrations of collagen or thrombin, but does not inhibit responses of washed rabbit platelets stimulated with high concentrations of ADP, collagen, or thrombin. However, when platelet responses to high concentrations of collagen or thrombin had been partially inhibited by prostacyclin (PGI2), ethanol had additional inhibitory effects on aggregation and secretion. These effects were also observed with aspirin- treated platelets stimulated with thrombin. Ethanol had no further inhibitory effect on aggregation of platelets stimulated with ADP, or the combination of ADP and epinephrine. Thus, the inhibitory effects of ethanol on platelet responses in the presence of PGI2 were very similar to its inhibitory effects in the absence of PGI2, when platelets were stimulated with lower concentrations of collagen or thrombin. Ethanol did not appear to exert its inhibitory effects by increasing cyclic AMP above basal levels and the additional inhibitory effects of ethanol in the presence of PGI2 did not appear to be brought about by further increases in platelet cyclic AMP levels.

PROPERTIES OF RAT ADRENAL ZONA RETICULARIS CELLS: PRODUCTION AND STIMULATION OF CERTAIN STEROIDS

1979 ◽  
Vol 83 (3) ◽  
pp. 435-447 ◽  
Author(s):  
J. B. G. BELL ◽  
R. P. GOULD ◽  
P. J. HYATT ◽  
J. F. TAIT ◽  
S. A. S. TAIT
Keyword(s):  
Adrenal Cortex ◽  
Significant Role ◽  
Zona Fasciculata ◽  
Cell Type ◽  
Acth Stimulation ◽  
Specific Stimulus ◽  
Zona Reticularis ◽  
Cell Pool ◽  
Stimulation Of

The outputs of corticosterone, deoxycorticosterone and androstenedione from dispersed, purified rat adrenal zona reticularis and zona fasciculata cells have been measured by radioimmunoassay. Preferential production of deoxycorticosterone by zona reticularis cells was demonstrated by their higher basal deoxycorticosterone: corticosterone ratio when compared with zona fasciculata cells. Adrenocorticotrophin (ACTH) stimulated corticosterone output by all cell pools prepared by unit gravity (1 g) sedimentation, zona fasciculata cells being stimulated 130-fold compared with 20-fold for the zona reticularis cells in relation to their basal corticosterone output. In every cell pool, ACTH stimulated the output of corticosterone more than it stimulated the output of deoxycorticosterone. In parallel cell preparations, it was shown that ACTH increased the conversion of tracer amounts of radioactive deoxycorticosterone to corticosterone and decreased the conversion of radioactive corticosterone to 11-dehydrocorticosterone. Adrenocorticotrophin did not increase the conversion of radioactive deoxycorticosterone to total 11-oxygenated steroids (corticosterone+ 11-dehydrocorticosterone). It is unlikely therefore that ACTH stimulates 11 β-hydroxylation. Data indicate that the ratio of deoxycorticosterone to total 11-oxygenated steroids (corticosterone +11-dehydrocorticosterone) is characteristic for each cell type, and that this ratio will be relatively independent of ACTH stimulation or the amount of pregnenolone substrate available. Basal androstenedione outputs were similar for both types of cell, and ACTH stimulation was very small, being slightly greater for zona fasciculata than for zona reticularis cells. The contribution of the zona reticularis cells to the basal output of any steroid by the cells of the inner two zones of the adrenal cortex of the rat was relatively small (20% for deoxycorticosterone and 10% for corticosterone) and was even less after stimulation by ACTH. Unless a specific stimulus can be found, therefore, a significant role for the zona reticularis cannot yet be established.

Experimental Mouse Muscle Damage: The Importance of External Calcium

1984 ◽  
Vol 66 (3) ◽  
pp. 317-322 ◽  
Author(s):  
D. A. Jones ◽  
M. J. Jackson ◽  
G. McPhail ◽  
R. H. T. Edwards
Keyword(s):  
Muscle Damage ◽  
Contractile Activity ◽  
Calcium Ionophore ◽  
Specific Effect ◽  
Extracellular Calcium ◽  
Enzyme Release ◽  
Mouse Muscle ◽  
Low Concentrations ◽  
Significant Release ◽  
Local Anaesthetic Action

1. The involvement of extracellular calcium in experimental muscle damage has been studied in an isolated mouse soleus muscle preparation. 2. The enzyme efflux and ultrastructural damage seen after excessive contractile activity were markedly reduced when the extracellular calcium was withdrawn. Low extracellular calcium also protected against the large enzyme efflux seen after treatment with low concentrations of detergent. 3. Treatment of the muscle with the calcium ionophore A 23187 caused significant release of enzyme from the muscle. 4. Nifedipine did not prevent the enzyme release after stimulation and although in some circumstances verapamil appeared to have some protective effect this was probably due to a local anaesthetic action on the muscle and not to any specific effect on calcium movement. 5. It is concluded that extracellular calcium is important in mediating at least the two forms of muscle damage studied here.

scholarly journals Receptor-mediated gonadotropin action in the ovary. Regulatory role of cyclic nucleotide phosphodiesterase(s) in intracellular adenosine 3′:5′-cyclic monophosphate turnover and gonadotropin-stimulated progesterone production by rat ovarian cells

1979 ◽  
Vol 180 (1) ◽  
pp. 201-211 ◽  
Author(s):  
Salman Azhar ◽  
K. M. Jairam Menon
Keyword(s):  
Cyclic Amp ◽  
Kinase Activity ◽  
Phosphodiesterase Inhibitors ◽  
Protein Kinase Activity ◽  
Dibutyryl Cyclic Amp ◽  
Steroid Production ◽  
Progesterone Production ◽  
Ovarian Cells ◽  
Cyclic Amp Accumulation

The regulatory role of cyclic nucleotide phosphodiesterase(s) and cyclic AMP metabolism in relation to progesterone production by gonadotropins has been studied in isolated rat ovarian cells. Low concentrations of choriogonadotropin (0.4–5ng/ml) increased steroid production without any detectable increase in cyclic AMP, when experiments were carried out in the absence of phosphodiesterase inhibitors. The concentration of choriogonadotropin (10ng/ml) that stimulated progesterone synthesis maximally resulted in a minimal increase in cyclic AMP accumulation and choriogonadotropin binding. Choriogonadotropin at a concentration of 10ng/ml and higher, however, significantly stimulated protein kinase activity and reached a maximum between 250 and 1000ng of hormone/ml. Higher concentrations (50–2500ng/ml) of choriogonadotropin caused an increase in endogenous cyclic AMP, and this increase preceded the increase in steroid synthesis. Analysis of dose–response relationships of gonadotropin-stimulated cyclic AMP accumulation, progesterone production and protein kinase activity revealed a correlation between these responses over a wide concentration range when experiments were performed in the presence of 3-isobutyl-1-methylxanthine. The phosphodiesterase inhibitors papaverine, theophylline and 3-isobutyl-1-methylxanthine each stimulated steroid production in a dose-dependent manner. Incubation of ovarian cells with dibutyryl cyclic AMP or 8-bromo cyclic AMP mimicked the steroidogenic action of gonadotropins and this effect was dependent on both incubation time and nucleotide concentration. Maximum stimulation was obtained with 2mm-dibutyryl cyclic AMP and 8-bromo cyclic AMP, and this increase was close to that produced by a maximally stimulating dose of choriogonadotropin. Other 8-substituted derivatives such as 8-hydroxy cyclic AMP and 8-isopropylthio cyclic AMP, which were less susceptible to phosphodiesterase action, also effectively stimulated steroidogenesis. The uptake and metabolism of cyclic [3H]AMP in ovarian cells was also studied in relation to steroidogenesis. When ovarian cells were incubated for 2h in the presence of increasing concentrations of cyclic [3H]AMP, the radioactivity associated with the cells increased almost linearly up to 250μm-cyclic [3H]AMP concentration in the incubation medium. The 3H label in the cellular extract was recovered mainly in the forms ATP, ADP, AMP, adenosine and inosine, with cyclic AMP accounting for less than 1% of the total tissue radioactivity. Incubation of cyclic AMP in vitro with ovarian cells resulted in a rapid breakdown of the nucleotide in the medium. The degradation products in the medium have been identified as AMP, adenosine and inosine. The rapid degradation of cyclic AMP by phosphodiesterase(s) makes it difficult to correlate changes in cyclic AMP concentrations with steroidogenesis. These observations thus provide an explanation for the previously observed lack of cyclic AMP accumulation under conditions in which low doses of choriogonadotropin stimulated steroidogenesis without any detectable changes in cyclic AMP accumulation.

scholarly journals Factors affecting the binding of [3H]adenosine 3′:5′-cyclic monophosphate to protein kinase from bovine adrenal cortex

1977 ◽  
Vol 161 (3) ◽  
pp. 653-665 ◽  
Author(s):  
S O Døskeland ◽  
P M Ueland ◽  
H J Haga
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Adrenal Cortex ◽  
Binding Sites ◽  
Binding Capacity ◽  
Binding Assays ◽  
Factors Affecting ◽  
Binding Characteristics ◽  
Standard Curve ◽  
Low Concentrations

Inorganic salts, several proteins and traces of protein precipitants were tested to find out by what mechanisms they modulate the binding of cyclic [3H]AMP to protein kinase (ATP-protein phosphotransferase; EC 2.7.1.37). The separation of free and bound cyclic AMP by (NH4)2SO4 precipitation was unaffected by the above agents and was more reliable than the Millipore filtration technique. Several binding sites for cyclic AMP were revealed in adrenal-cortex extract. When this extract was used as binding reagent in an assay for cyclic AMP, the standard curve was distorted in the presence of KCl because the salt affected the different binding sites to a varying extent. At high ionic strenth the protein kinase isoenzyme I dissociated and showed an extraordinarily high affinity for cyclic AMP. Trichloroacetate and perchlorate at very low concentrations were able to dissociate the protein kinase and modulate its binding characteristics as well. A progressive decrease in the cyclic AMP-binding capacity occurred on prolonged incubations. The binding protein was protected against inactivation by 2-mercaptoethanol, EDTA and several proteins. It was more resistant to denaturation when complexed to cyclic AMP. The enhancement of cyclic AMP binding by bovine serum albumin was investigated in some detail and appeared to be a pure stabilizing effect. It is proposed that the competitive-binding assays for cyclic AMP based on protein kinase be conducted at high ionic strength and in the presence of stabilizers (protein, EDTA, 2-mercaptoethanol). The interference from agents that may dissociate the protein kinase or influence its stability will thus be decreased.

scholarly journals Adenosine 3':5'-monophosphate content and actions in the division cycle of synchronized HeLa cells.

1976 ◽  
Vol 71 (2) ◽  
pp. 515-534 ◽  
Author(s):  
C E Zeilig ◽  
R A Johnson ◽  
E W Sutherland ◽  
D L Friedman
Keyword(s):  
Cell Cycle ◽  
Cyclic Amp ◽  
Hela Cells ◽  
S Phase ◽  
Intracellular Camp ◽  
Specific Effects ◽  
Low Concentrations ◽  
High Concentrations ◽  
Camp Levels ◽  
Stimulation Of

The involvement of adenosine 3':5'-monophosphate (cAMP) in the regulation of the cell cycle was studied by determining intracellular fluctuations in cAMP levels in synchronized HeLa cells and by testing the effects of experimentally altered levels on cell cycle traverse. Cyclic AMP levels were lowest during mitosis and were highest during late G-1 or early S phase. These findings were supported by results obtained when cells were accumulated at these points with Colcemid or high levels of thymidine. Additional fluctuations in cAMP levels were observed during S phase. Two specific effects of cAMP on cell cycle traverse were found. Elevation of cAMP levels in S phase or G-2 caused arrest of cells in G-2 for as long as 10 h and lengthened M. However, once cells reached metaphase, elevation of cAMP accelerated the completion of mitosis. Stimulation of mitosis was also observed after addition of CaCl2. The specificity of the effects of cAMP was verified by demonstrating that: (a) intracellular cAMP was increased after exposure to methylisobutylxanthine (MIX) before any observed effects on cycle traverse; (b) submaximal concentrations of MIX potentiated the effects of isoproterenol; and (c) effects of MIX and isoproterenol were mimicked by 8-Br-cAMP. MIX at high concentrations inhibited G-1 traverse, but this effect did not appear to be mediated by cAMP. Isoproterenol slightly stimulated G-1 traverse and partially prevented the MIX-induced delay. Moreover, low concentrations of 8-Br-cAMP (0.10-100 muM) stimulated G-1 traverse, whereas high concentrations (1 mM) inhibited. Both of these effects were also observed with the control, Br-5'-AMP, at 10-fold lower concentrations.

scholarly journals Temperature dependence of plasmin-induced activation or inhibition of human platelets

Blood ◽  
1991 ◽  
Vol 77 (5) ◽  
pp. 996-1005 ◽  
Author(s):  
H Lu ◽  
C Soria ◽  
EM Cramer ◽  
J Soria ◽  
J Maclouf ◽  
...  
Keyword(s):  
Incubation Temperature ◽  
Calcium Ionophore ◽  
Human Platelets ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Platelet Response ◽  
Induce Platelet Aggregation ◽  
Ultrastructural Studies ◽  
Low Concentrations ◽  
High Concentrations

Abstract It is known that at 37 degrees C plasmin may have two opposite effects on platelets: at high concentrations (greater than 1.5 caseinolytic units [CU]/mL), plasmin activates platelets; at lower concentrations (0.1 to 1.0 CU/mL) it inhibits platelet activation induced by thrombin, collagen, or calcium ionophore A23187. In this study, we report that when lowering the incubation temperature to 22 degrees C, plasmin at low concentrations (0.1 to 0.5 CU/mL) fully activated platelets. When platelets were treated with 0.2 CU/mL of plasmin, lowering the incubation temperature from 37 degrees C to 22 degrees C resulted in an increase in the expression of fibrinogen receptors, in platelet release and aggregation. Thromboxane A2 was not generated by plasmin treatment at either temperature. Ultrastructural studies showed that platelets responded to low-dose plasmin at 37 degrees C by forming pseudopods, centralizing granules without fibrinogen release, whereas at 22 degrees C the same dose of plasmin caused platelet degranulation with the appearance of alpha-granule fibrinogen within the lumen of the surface connected canalicular system. In addition, at 22 degrees C plasmin at doses insufficient to induce platelet aggregation potentiated platelet response to thrombin. Thus, we suggest that plasmin may initiate both activating and inhibitory processes within platelets and that the change of temperature could influence this balance. These results may be of clinical relevance, because the fibrinolytic system was found activated during cardiopulmonary bypass in which the temperature of patient's blood circulation was reduced. This temperature-dependent behavior is also an interesting model for a further study on platelet response to serine proteinases.

scholarly journals Biochemical effects of diquat and paraquat. Disturbance of the control of corticosteroid synthesis in rat adrenal and subsequent effects on the control of liver glycogen utilization

1974 ◽  
Vol 138 (3) ◽  
pp. 437-443 ◽  
Author(s):  
Michael S. Rose ◽  
Helen C. Crabtree ◽  
Kenneth Fletcher ◽  
Ian Wyatt
Keyword(s):  
Blood Glucose ◽  
Cyclic Amp ◽  
Adrenal Cortex ◽  
Normal Values ◽  
Liver Glycogen ◽  
Plasma Acth ◽  
Biochemical Effects ◽  
Glycogen Utilization ◽  
High Concentrations ◽  
Very High

1. Administration of diquat (NN′-ethylene-2,2′-bipyridilium) or paraquat (NN′-dimethyl-4,4′-bipyridilium) prevents the normal depletion of liver glycogen in starved rats. 2. There is an increase in blood glucose, which returns to normal values after approx. 7h. 3. After administration of diquat or paraquat, plasma corticosteroids increase to very high concentrations and remain high for at least 24h, but plasma ACTH (adrenocorticotrophin) is only increased for 4h. 4. Adrenal cyclic AMP is considerably increased after administration of diquat and remains significantly higher than control values for at least 24h. 5. It is suggested that diquat and paraquat increase the response of the adrenal cortex to ACTH.

scholarly journals The effects of potassium, 5-hydroxytryptamine, adrenocorticotrophin and angiotensin II on the concentration of adenosine 3′:5′-cyclic monophosphate in suspensions of dispersed rat adrenal zona glomerulosa and zona fasciculata cells

1974 ◽  
Vol 142 (2) ◽  
pp. 391-400 ◽  
Author(s):  
Janet D. M. Albano ◽  
Barry L. Brown ◽  
Roger P. Ekins ◽  
Sylvia A. S. Tait ◽  
James F. Tait
Keyword(s):  
Angiotensin Ii ◽  
Bovine Serum Albumin ◽  
Cyclic Amp ◽  
Adrenal Gland ◽  
Incubation Medium ◽  
Zona Glomerulosa ◽  
Zona Fasciculata ◽  
Adrenal Cells ◽  
Cyclic Amp Accumulation ◽  
K Concentration

Dispersed rat adrenal cells prepared from both the capsule and the decapsulated gland were used to investigate the effects on cyclic AMP accumulation of known stimuli of steroidogenesis [ACTH (adrenocorticotrophin), angiotensin II, K+ions and 5-hydroxytryptamine]. Since glomerulosa-cell preparations from capsular strippings are normally contaminated with a proportion of fasciculata cells, cells purified by fractionation on a bovine serum albumin gradient were also used. The results showed that: (1) ACTH and angiotensin II stimulated cyclic AMP accumulation in both fractionated and unfractionated zona fasciculata cells; (2) 5-hydroxytryptamine and an increased extracellular K+concentration (from 3.6 to 8.4mm) had no effect on cyclic AMP concentrations in fasciculata cell preparations; (3) the addition of ACTH, angiotensin II, 5-hydroxytryptamine or K+to the incubation medium resulted in increased cyclic AMP concentrations in unpurified zona glomerulosa cell preparations; (4) fractionation and hence the virtual elimination of fasciculata contamination, did not affect the response to 5-hydroxytryptamine and increased K+concentration. However, the responses to ACTH and angiotensin II were markedly lowered but not abolished. These results strongly suggest a link between cyclic AMP production and steroidogenesis in the zone of the adrenal gland that specifically secretes aldosterone. All four agents used stimulated both steroid output and cyclic AMP accumulation. However, at certain doses of 5-hydroxytryptamine, K+and angiotensin II the significant increases in corticosterone output were not accompanied by measurable increases in cyclic AMP accumulation.

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