scholarly journals The role of calcium influx pathways in phospholipase D activation in bovine adrenal glomerulosa cells

2009 ◽  
Vol 202 (1) ◽  
pp. 77-86 ◽  
Author(s):  
Haixia Qin ◽  
Patricia Kent ◽  
Carlos M Isales ◽  
Peter M Parker ◽  
Mariya V Wilson ◽  
...  
Keyword(s):  
Phospholipase D ◽  
Calcium Influx ◽  
Cell Model ◽  
Primary Cultures ◽  
Extracellular Potassium ◽  
Voltage Dependent ◽  
H295r Cells ◽  
Glomerulosa Cells ◽  
Influx Pathways

The steroid hormone aldosterone maintains sodium homeostasis and is therefore important in the control of blood volume and pressure. Angiotensin II (AngII) and elevated extracellular potassium concentrations ([K+]e), the prime physiologic regulators of aldosterone secretion from adrenal glomerulosa cells, activate phospholipase D (PLD) in these cells. The role of Ca2+ in the activation by these agents is unknown, although nitrendipine, a voltage-dependent Ca2+ channel antagonist, does not inhibit AngII-elicited PLD activation, despite the fact that this compound blocked elevated [K+]e-stimulated PLD activity. PLD activation triggered by AngII was also unaffected by the T-type calcium channel inhibitor nickel. Nevertheless, Ca2+ influx was required for AngII-induced PLD activation in both primary cultures of bovine adrenal glomerulosa cells and a glomerulosa cell model, the NCI H295R adrenocortical carcinoma cell line. The involvement of store-operated Ca2+ (SOC) influx and Ca2+ release-activated Ca2+ (CRAC) influx pathways in PLD activation was investigated using thapsigargin, an endoplasmic reticulum Ca2+ pump inhibitor that empties the store to induce SOC influx, and the SOC inhibitor YM-58483 (BTP2), as well as a CRAC inhibitor, tyrphostin A9. In bovine glomerulosa cells, tyrphostin A9 inhibited AngII-induced PLD activation without affecting elevated [K+]e-stimulated enzyme activity. On the other hand, differences were observed between the bovine adrenal glomerulosa and H295R cells in the involvement of Ca2+ influx pathways in PLD activation, with the involvement of the SOC pathway suggested in the H295R cells. In summary, our results indicate that Ca2+ entry only through certain Ca2+ influx pathways is linked to PLD activation.

Resting calcium influx in airway smooth muscle

2005 ◽  
Vol 83 (8-9) ◽  
pp. 717-723 ◽  
Author(s):  
Luis M Montaño ◽  
Blanca Bazán-Perkins
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Airway Smooth Muscle ◽  
Calcium Influx ◽  
Physiological Role ◽  
Resting Membrane Potential ◽  
Voltage Dependent ◽  
Intracellular Ca ◽  
Influx Pathways

Plasma membrane Ca2+ leak remains the most uncertain of the cellular Ca2+ regulation pathways. During passive Ca2+ influx in non-stimulated smooth muscle cells, basal activity of constitutive Ca2+ channels seems to be involved. In vascular smooth muscle, the 3 following Ca2+ entry pathways contribute to this phenomenon: (i) via voltage-dependent Ca2+ channels, (ii) receptor gated Ca2+ channels, and (iii) store operated Ca2+ channels, although, in airway smooth muscle it seems only 2 passive Ca2+ influx pathways are implicated, one sensitive to SKF 96365 (receptor gated Ca2+ channels) and the other to Ni2+ (store operated Ca2+ channels). Resting Ca2+ entry could provide a sufficient amount of Ca2+ and contribute to resting intracellular Ca2+ concentration ([Ca2+]i), maintenance of the resting membrane potential, myogenic tone, and sarcoplasmic reticulum-Ca2+ refilling. However, further research, especially in airway smooth muscle, is required to better explore the physiological role of this passive Ca2+ influx pathway as it could be involved in airway hyperresponsiveness.Key words: basal Ca2+ entry, constitutive Ca2+ channels, airway and vascular smooth muscle, SKF 96365, Ni2+.

The role of voltage-dependent calcium channels in angiotensin-stmulated glomerulosa cells

1996 ◽  
Vol 22 (4) ◽  
pp. 569-576 ◽  
Author(s):  
A. Spät ◽  
T. Rohács ◽  
A. Horváth ◽  
G Y. Szabadkai ◽  
P. Enyedi
Keyword(s):  
Calcium Channels ◽  
Voltage Dependent ◽  
Voltage Dependent Calcium Channels ◽  
Glomerulosa Cells

scholarly journals Phospholipase D2 Mediates Acute Aldosterone Secretion in Response to Angiotensin II in Adrenal Glomerulosa Cells

Endocrinology ◽  
2010 ◽  
Vol 151 (5) ◽  
pp. 2162-2170 ◽  
Author(s):  
Haixia Qin ◽  
Michael A. Frohman ◽  
Wendy B. Bollag
Keyword(s):  
Plasma Membrane ◽  
Angiotensin Ii ◽  
Cell Surface ◽  
Phosphatidic Acid ◽  
Phospholipase D ◽  
Cell Interior ◽  
Aldosterone Secretion ◽  
Phospholipase D2 ◽  
Glomerulosa Cells

In primary bovine adrenal glomerulosa cells, the signaling enzyme phospholipase D (PLD) is suggested to mediate priming, the enhancement of aldosterone secretion after pretreatment with and removal of angiotensin II (AngII), via the formation of persistently elevated diacylglycerol (DAG). To further explore PLD’s role in priming, glomerulosa cells were pretreated with an exogenous bacterial PLD. Using this approach, phosphatidic acid (PA) is generated on the outer, rather than the inner, leaflet of the plasma membrane. Although PA is not readily internalized, the PA is nonetheless rapidly hydrolyzed by cell-surface PA phosphatases to DAG, which efficiently flips to the inner leaflet and accesses the cell interior. Pretreatment with bacterial PLD resulted in priming upon subsequent AngII exposure, supporting a role of DAG in this process, because the increase in DAG persisted after exogenous PLD removal. To determine the PLD isoform mediating aldosterone secretion, and presumably priming, primary glomerulosa cells were infected with adenoviruses expressing GFP, PLD1, PLD2, or lipase-inactive mutants. Overexpressed PLD2 increased aldosterone secretion by approximately 3-fold over the GFP-infected control under basal conditions, with a significant enhancement to about 16-fold over the basal value upon AngII stimulation. PLD activity was also increased basally and upon stimulation with AngII. In contrast, PLD1 overexpression had little effect on aldosterone secretion, despite the fact that PLD activity was enhanced. In both cases, the lipase-inactive PLD mutants showed essentially no effect on PLD activity or aldosterone secretion. Our results suggest that PLD2 is the isoform that mediates aldosterone secretion and likely priming.

scholarly journals Phospholipase D Activity Underlies Very-Low-Density Lipoprotein (VLDL)-induced Aldosterone Production in Adrenal Glomerulosa Cells

Endocrinology ◽  
2014 ◽  
Vol 155 (9) ◽  
pp. 3550-3560 ◽  
Author(s):  
Ying-Ying Tsai ◽  
William E. Rainey ◽  
Zhi-qiang Pan ◽  
Michael A. Frohman ◽  
Vivek Choudhary ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Phospholipase D ◽  
Low Density Lipoprotein ◽  
Primary Cultures ◽  
Density Lipoprotein ◽  
Very Low Density Lipoprotein ◽  
Low Density ◽  
Peripheral Tissues ◽  
Aldosterone Production ◽  
Glomerulosa Cells

Abstract Aldosterone is the mineralocorticoid responsible for sodium retention, thus increased blood volume and pressure. Excessive production of aldosterone results in high blood pressure as well as renal disease, stroke, and visual loss via both direct effects and effects on blood pressure. Weight gain is often associated with increased blood pressure, but it remains unclear how obesity increases blood pressure. Obese patients typically have higher lipoprotein levels; moreover, some studies have suggested that aldosterone levels are also elevated and represent a link between obesity and hypertension. Very-low-density lipoprotein (VLDL) functions to transport triglycerides from the liver to peripheral tissues. Although previous studies have demonstrated that VLDL can stimulate aldosterone production, the mechanisms underlying this effect are largely unclear. Here we show for the first time that phospholipase D (PLD) is involved in VLDL-induced aldosterone production in both a human adrenocortical cell line (HAC15) and primary cultures of bovine zona glomerulosa cells. Our data also reveal that PLD mediates steroidogenic acute regulatory (StAR) protein and aldosterone synthase (CYP11B2) expression via increasing the phosphorylation (activation) of their regulatory transcription factors. Finally, by using selective PLD inhibitors, our studies suggest that both PLD1 and PLD2 isoforms play an important role in VLDL-induced aldosterone production.

Effect of osmolality on cytosolic free calcium and aldosterone secretion

1992 ◽  
Vol 262 (1) ◽  
pp. E68-E75 ◽  
Author(s):  
W. Wang ◽  
N. Hayama ◽  
T. V. Robinson ◽  
R. E. Kramer ◽  
E. G. Schneider
Keyword(s):  
Calcium Influx ◽  
Potassium Concentration ◽  
Sodium Concentration ◽  
Cytosolic Calcium ◽  
Extracellular Calcium ◽  
Free Calcium ◽  
Aldosterone Secretion ◽  
Voltage Dependent ◽  
Glomerulosa Cells ◽  
Dose Dependent

Alterations in extracellular osmolality have powerful inverse effects on basal and potassium- and angiotensin-stimulated aldosterone secretion. With the use of bovine glomerulosa cells grown in primary culture, the effects of alterations in osmolality on cytosolic calcium concentration ([Ca2+]c), efflux and uptake of 45Ca2+, and aldosterone secretion were determined. Alterations in osmolality, independent of sodium concentration, have inverse effects on aldosterone secretion, which are correlated with simultaneous changes in [Ca2+]c measured using fura-2. Reductions in osmolality cause dose-dependent biphasic increases in [Ca2+]c different from the monophasic increases in [Ca2+]c produced by increases in potassium concentration. Like potassium- and angiotensin-stimulated increases in [Ca2+]c, hypotonically induced increases in [Ca2+]c are associated with an increase in 45Ca2+ efflux. Reductions in osmolality also increased the uptake of 45Ca2+, an effect apparent at 2 min and persistent for at least 30 min. In the absence of extracellular calcium, reductions in osmolality, as increases in potassium concentration but not angiotensin, fail to increase [Ca2+]c, efflux of 45Ca2+, or aldosterone secretion. In conclusion, osmolality-induced alterations in aldosterone secretion are associated with parallel changes in [Ca2+]c, effects caused by alteration in the influx of extracellular calcium. On the basis of these and previous studies, we hypothesize that osmolality affects calcium influx by activating voltage-dependent or stretch-activated calcium channels.

Calcium signaling pathways utilized by P2X receptors in freshly isolated preglomerular MVSMC

2001 ◽  
Vol 280 (6) ◽  
pp. F1054-F1061 ◽  
Author(s):  
Steven M. White ◽  
John D. Imig ◽  
Thu-Thuy Kim ◽  
Benjamin C. Hauschild ◽  
Edward W. Inscho
Keyword(s):  
Calcium Influx ◽  
Receptor Activation ◽  
P2x Receptors ◽  
Transient Increase ◽  
P2x Receptor ◽  
The Novel ◽  
Peak Response ◽  
Voltage Dependent ◽  
Intracellular Ca ◽  
Influx Pathways

This study tested the hypothesis that P2X receptor activation increases intracellular Ca2+concentration ([Ca2+]i) in preglomerular microvascular smooth muscle cells (MVSMC) by evoking voltage-dependent calcium influx. MVSMC were obtained and loaded with the calcium-sensitive dye fura 2 and studied by using single-cell fluorescence microscopy. The effect of P2X receptor activation on [Ca2+]i was assessed by using the P2X receptor-selective agonist α,β-methylene-ATP and was compared with responses elicited by the endogenous P2 receptor agonist ATP. α,β-Methylene-ATP increased [Ca2+]i dose dependently. Peak increases in [Ca2+]iaveraged 37 ± 11, 73 ± 15, and 103 ± 21 nM at agonist concentrations of 0.1, 1, and 10 μM, respectively. The average peak response elicited by 10 μM α,β-methylene-ATP was ∼34% of the response obtained with 10 μM ATP. α,β-Methylene-ATP induced a transient increase in [Ca2+]i before [Ca2+]i returned to baseline, whereas ATP induced a biphasic response including a peak response followed by a sustained plateau. In Ca2+-free medium, ATP induced a sharp transient increase in [Ca2+]i, whereas the response to α,β-methylene-ATP was abolished. Ca2+channel blockade with 10 μM diltiazem or nifedipine attenuated the response to α,β-methylene-ATP, whereas nonspecific blockade of Ca2+ influx pathways with 5 mM Ni2+ abolished the response. Blockade of P2X receptors with the novel P2X receptor antagonist NF-279 completely but reversibly abolished the response to α,β-methylene-ATP. These results indicate that P2X receptor activation by α,β-methylene-ATP increases [Ca2+]i in preglomerular MVSMC, in part, by stimulating voltage-dependent Ca2+ influx through L-type Ca2+ channels.

scholarly journals Autocrine role of adrenomedullin in the human adrenal cortex

2001 ◽  
Vol 170 (1) ◽  
pp. 259-265 ◽  
Author(s):  
LM Thomson ◽  
S Kapas ◽  
M Carroll ◽  
JP Hinson
Keyword(s):  
Cell Line ◽  
Second Messenger ◽  
Cell Types ◽  
Zona Glomerulosa ◽  
Adrenocortical Cell ◽  
Gene Encoding ◽  
Calcitonin Gene ◽  
H295r Cells ◽  
Glomerulosa Cells

Previous studies from our laboratory have reported that adrenomedullin is synthesised in rat zona glomerulosa cells. In the present studies, it was found that the human adrenocortical cell line H295R expresses the gene encoding adrenomedullin, and that immunoreactive adrenomedullin is released into the culture medium. Furthermore, it was found that secretion of adrenomedullin is regulated by angiotensin II and forskolin. Studies on the actions of adrenomedullin and calcitonin gene-related peptide (CGRP) revealed a stimulatory effect of adrenomedullin, but not of CGRP, on aldosterone and cortisol secretion. These data suggest that adrenomedullin is not acting by a CGRP receptor-mediated mechanism in the H295R cell line. Adrenomedullin was also found to increase cAMP production, suggesting that in the adrenal, as in other cell types, cAMP is a second messenger for adrenomedullin action. However, the effects of adrenomedullin were not fully mimicked by forskolin, possibly suggesting a role for an additional second messenger. The presence of mRNA encoding both the putative adrenomedullin receptors, L1 and calcitonin receptorlike receptor/receptor-associated modulatory protein 2 (CRLR/RAMP-2), was demonstrated in H295R cells, but RAMP-1 was not detected, suggesting that these cells do not express the CGRPI receptor CRLR/RAMP-1. Taken together, these data have demonstrated that adrenomedullin is synthesised and secreted by H295R cells. The observed rate of adrenomedullin synthesis suggests that this peptide exerts a paracrine/autocrine effect in this adrenocortical cell line, probably acting through a specific adrenomedullin receptor, to stimulate steroidogenesis and increase aldosterone synthase expression.

Duality of the voltage-dependent calcium influx in adrenal glomerulosa cells

1998 ◽  
Vol 24 (3-4) ◽  
pp. 443-447 ◽  
Author(s):  
M. F. Rossier ◽  
M. M. Burnay ◽  
A. Maturana ◽  
A. M. Capponi
Keyword(s):  
Calcium Influx ◽  
Voltage Dependent ◽  
Glomerulosa Cells

scholarly journals The Slack Sodium-Activated Potassium Channel Provides a Major Outward Current in Olfactory Neurons of Kv1.3−/− Super-Smeller Mice

2010 ◽  
Vol 103 (6) ◽  
pp. 3311-3319 ◽  
Author(s):  
Songqing Lu ◽  
Paromita Das ◽  
Debra A. Fadool ◽  
Leonard K. Kaczmarek
Keyword(s):  
Potassium Channel ◽  
Primary Cultures ◽  
Outward Current ◽  
Mitral Cells ◽  
Olfactory Neurons ◽  
Outward Currents ◽  
Voltage Dependent ◽  
Enhanced Expression ◽  
H Channels

The Kv1.3 voltage-dependent potassium channel is expressed at high levels in mitral cells of the olfactory bulb (OB). Deletion of the Kv1.3 potassium channel gene (Kv1.3−/−) in mice lowers the threshold for detection of odors, increases the ability to discriminate between odors, and alters the firing pattern of mitral cells. We have now found that loss of Kv1.3 produces a compensatory increase in Na+-activated K+ currents (KNa) in mitral cells. Levels of the KNa channel subunit Slack-B determined by Western blotting are substantially increased in the OB from Kv1.3−/− animals compared with those of wildtype animals. In voltage-clamp recordings of OB slices, elevation of intracellular sodium from 0 to 60 mM increased mean outward currents by 15% in mitral cells from wildtype animals and by 40% in cells from Kv1.3−/− animals. In Kv1.3−/− cells, KNa current could even be detected with 0 mM Na+ internal solutions, provided extracellular Na+ was present, and this current could be abolished by TTX and ZD7288, blockers of Na+ influx through voltage-dependent Na+ channels and H-channels, respectively. The role of enhanced expression of Slack subunits in the increase of KNa current in Kv1.3−/− cells was also confirmed using an RNA interference (RNAi) approach to suppress Slack expression in primary cultures of olfactory neurons. In Kv1.3−/− neurons, treatment with Slack-specific RNAi inhibited approximately 75% of the net outward current, whereas in wildtype cells, the same treatment suppressed only about 25% of the total current. Scrambled and mismatched RNAi oligonucleotides failed to suppress currents. Our findings raise the possibility that the olfactory phenotype of Kv1.3−/− animals results in part from an enhancement of KNa currents.

INVESTIGATIONS INTO THE ROLE OF CALCIUM IONS IN THE CONTROL OF STEROID PRODUCTION BY ISOLATED ADRENAL ZONA GLOMERULOSA CELLS OF THE RAT

1978 ◽  
Vol 77 (1) ◽  
pp. 119-127 ◽  
Author(s):  
CAROLINE MACKIE ◽  
R. L. WARREN ◽  
E. R. SIMPSON
Keyword(s):  
Calcium Content ◽  
Zona Glomerulosa ◽  
Extracellular Potassium ◽  
Total Calcium ◽  
Calcium Efflux ◽  
Delayed Effect ◽  
Steroid Production ◽  
Glomerulosa Cells ◽  
Zona Glomerulosa Cells

An increase in the concentration of extracellular potassium from 3·6 to 8·4 mmol/l had only a small delayed effect on the uptake of radioactive calcium by isolated adrenal glomerulosa cells. However, the same stimulus had a rapid and highly significant effect on the efflux of radioactive calcium from glomerulosa cells preloaded with 45Ca2+. Cells incubated in medium containing 8·4 mmol potassium/l had retained approximately 15% more radioactivity than control cells after 2·5 min and this difference was maintained for up to 90 min. There was an increase in the production of steroids by the glomerulosa cells in the presence of 8·4 mm-potassium. No effect on calcium efflux was observed in similar experiments with isolated fasciculata cells; it has been established that this concentration of potassium does not affect steroidogenesis in fasciculata cells, indicating that the effect on glomerulosa cells may be causally linked to steroidogenesis. There was no significant change in the total calcium content of glomerulosa cells in the presence of 8·4 mm-potassium. Exchangeable calcium in these cells was found to be 60% of the total calcium content.

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