Stimulation of Ca2+ influx in αT3–1 gonadotrophs via the cAMP/PKA signaling system

1997 ◽  
Vol 273 (5) ◽  
pp. E850-E858 ◽  
Author(s):  
Marjan Hezareh ◽  
Werner Schlegel ◽  
Stephen R. Rawlings
Keyword(s):  
Adenylate Cyclase ◽  
Calcium Concentration ◽  
Cytosolic Calcium ◽  
Camp Signaling ◽  
Signaling System ◽  
Cyclic Monophosphate ◽  
Pituitary Adenylate Cyclase ◽  
Inositol 1,4,5 Trisphosphate ◽  
Made In ◽  
Stimulation Of

To investigate the regulation of free cytosolic calcium concentration ([Ca2+]i) by the adenosine 3′,5′-cyclic monophosphate (cAMP) signaling system in clonal gonadotrophs, microfluorimetric recordings were made in single indo 1-loaded αT3–1 cells. Forskolin, 8-bromoadenosine 3′,5′-cyclic monophosphate, or a low concentration (100 pM) of the hypothalamic factor pituitary adenylate cyclase-activating polypeptide (PACAP) stimulated Ca2+ step responses or repetitive Ca2+ transients, which were blocked by the removal of extracellular Ca2+ by the dihydropyridine (DHP) (+)PN 200–110 or by preincubation with the protein kinase A (PKA) antagonist H-89 (10 μM). Thus activation of the cAMP/PKA system in αT3–1 gonadotrophs stimulates Ca2+ influx through DHP-sensitive (L-type) Ca2+ channels. In contrast, high PACAP concentrations (100 nM) stimulated biphasic Ca2+ spike-plateau responses. The Ca2+ spike was independent of extracellular Ca2+, and similar responses were observed by microperfusion of individual cells withd- myo-inositol 1,4,5-trisphosphate, suggesting the involvement of the phospholipase C (PLC) signaling pathway. The Ca2+plateau depended on Ca2+ influx, was blocked by (+)PN 200–110, but was only partially blocked by H-89 pretreatment. In conclusion, PACAP stimulates [Ca2+]iincreases in αT3–1 gonadotrophs through both the PLC and adenylate cyclase signaling pathways. Furthermore, this is the first clear demonstration that the cAMP/PKA system can mediate changes in [Ca2+]iin gonadotroph-like cells.

scholarly journals Stimulation of Cyclic AMP Formation by Pituitary Adenylate Cyclase-Activating Polypeptide Is Attenuated by Glutamate in Rat Brain Slices

1995 ◽  
Vol 67 (4) ◽  
pp. 399-402
Author(s):  
Kaoru Kondo ◽  
Hitoshi Hashimoto ◽  
Kazuko Sakata ◽  
Hiroshi Saga ◽  
Jun-ichi Kitanaka ◽  
...  
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Rat Brain ◽  
Brain Slices ◽  
Pituitary Adenylate Cyclase ◽  
Stimulation Of

Changes in cytosolic cGMP and calcium in airway smooth muscle relaxed by 3-morpholinosydnonimine

1994 ◽  
Vol 266 (1) ◽  
pp. L9-L16 ◽  
Author(s):  
K. A. Jones ◽  
R. R. Lorenz ◽  
D. O. Warner ◽  
Z. S. Katusic ◽  
G. C. Sieck
Keyword(s):  
Methylene Blue ◽  
Smooth Muscle ◽  
Airway Smooth Muscle ◽  
Calcium Concentration ◽  
Cytosolic Calcium ◽  
Tracheal Smooth Muscle ◽  
Relative Importance ◽  
Cytosolic Calcium Concentration ◽  
Fura 2 ◽  
Cyclic Monophosphate

Nitrovasodilators relax airway smooth muscle by both guanosine 3',5'-cyclic monophosphate (cGMP)-dependent and cGMP-independent mechanisms and by mechanisms that reduce cytosolic calcium concentration ([Ca2+]i). This study was conducted to determine the relative importance of these mechanisms in relaxation of canine tracheal smooth muscle (CTSM) induced by 3-morpholinosydnonimine (SIN-1). We measured 1) the effect of SIN-1 on force, [cGMP]i, and [Ca2+]i, and 2) the ability of methylene blue (MB) to antagonize SIN-1-induced relaxation and cGMP accumulation. The ratio of fura 2 emission fluorescence intensities due to excitation at 340- and 380-nm wavelengths (F340/F380) was used as an index of [Ca2+]i. In strips contracted with 0.3 microM acetylcholine (ACh, n = 8) or 24 mM KCl (n = 8), SIN-1 (1-100 microM) caused a concentration-dependent decrease in force which was correlated with a concentration-dependent increase in [cGMP]i. MB (10 microM) proportionally attenuated both relaxation and cGMP accumulation. In fura 2-loaded strips contracted with 0.3 microM ACh (n = 7) or 30 mM KCl (n = 7), reductions in force induced by SIN-1 (1-100 microM) were accompanied by decreases in F340/F380. These findings suggest that in CTSM contracted with ACh or KCl, SIN-1 causes relaxation which appears to be mediated by cGMP-dependent mechanisms that reduce [Ca2+]i.

Effects of barbiturates on human platelet aggregation differ depending on their chemical structures

2003 ◽  
Vol 81 (8) ◽  
pp. 806-814 ◽  
Author(s):  
Masami Sato ◽  
Hideo Hirakata ◽  
Masahiro Ikeda ◽  
Kazuhiko Fukuda
Keyword(s):  
Platelet Aggregation ◽  
Calcium Concentration ◽  
Light Transmission ◽  
Human Platelet ◽  
Clinical Importance ◽  
Cytosolic Calcium ◽  
Free Calcium ◽  
Chemical Structures ◽  
Human Platelet Aggregation ◽  
Inositol 1,4,5 Trisphosphate

The effects of barbiturates on human platelet function are not fully understood. Since we have already revealed the effects and mechanisms of thiopental, thiamylal, and pentobarbital in platelets, the present study attempted to elucidate (i) the effects of other barbiturates on human platelet aggregation, (ii) the underlying mechanisms, and (iii) the structure–function relationship of barbiturates in platelets. Barbiturates, including amobarbital, butalbital, secobarbital, barbital, phenobarbital, metharbital, and primidone, were examined. Human platelet aggregation induced by adenosine diphosphate (ADP), epinephrine, and (+)-9,11-epithia-11,12-methano-thromboxane A2 (STA2), a thromboxane A2 analog, was measured using an 8-channel light-transmission aggregometer. The cytosolic free calcium concentration ([Ca2+]i) was measured by fluorometer using fura-2 loaded platelets. Inositol 1,4,5-trisphosphate (IP3) formation induced by STA2 was determined by a commercially available IP3 assay kit. Amobarbital, butalbital, and secobarbital suppressed ADP-, epinephrine- and STA2-induced platelet aggregation and the STA2-induced [Ca2+]i increase, even when Ca2+ influx was blocked by Ni2+. However, they did not affect STA2-induced IP3 formation. Barbital, phenobarbital, metharbital, and primidone (up to 1 mM) had no effect on ADP- and epinephrine-induced platelet aggregation. Thus, we conclude that amobarbital, butalbital, and secobarbital inhibit platelet aggregation by suppressing [Ca2+]i increase without affecting IP3 formation. However, these antiaggregatory effects may not have clinical importance, since the barbiturate concentrations used were higher than clinically relevant ones. The other tested barbiturates had no effects on platelet aggregation. The data indicate that the effects of barbiturates on platelet aggregation differ depending on their chemical structures.Key words: platelet aggregation, barbiturates, cytosolic calcium concentration, inositol 1,4,5-trisphosphate.

scholarly journals Propofol Affects Neurodegeneration and Neurogenesis by Regulation of Autophagy via Effects on Intracellular Calcium Homeostasis

2017 ◽  
Vol 127 (3) ◽  
pp. 490-501 ◽  
Author(s):  
Hui Qiao ◽  
Yun Li ◽  
Zhendong Xu ◽  
Wenxian Li ◽  
Zhijian Fu ◽  
...  
Keyword(s):  
Cell Survival ◽  
Progenitor Cells ◽  
Cell Fate ◽  
Calcium Concentration ◽  
Neural Progenitor Cells ◽  
Cytosolic Calcium ◽  
Neural Progenitor ◽  
Mediated Effects ◽  
Proliferation And Differentiation ◽  
Inositol 1,4,5 Trisphosphate

Abstract Background In human cortical neural progenitor cells, we investigated the effects of propofol on calcium homeostasis in both the ryanodine and inositol 1,4,5-trisphosphate calcium release channels. We also studied propofol-mediated effects on autophagy, cell survival, and neuro- and gliogenesis. Methods The dose–response relationship between propofol concentration and duration was studied in neural progenitor cells. Cell viability was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and lactate dehydrogenase release assays. The effects of propofol on cytosolic calcium concentration were evaluated using Fura-2, and autophagy activity was determined by LC3II expression levels with Western blot. Proliferation and differentiation were evaluated by bromodeoxyuridine incorporation and immunostaining with neuronal and glial markers. Results Propofol dose- and time-dependently induced cell damage and elevated LC3II expression, most robustly at 200 µM for 24 h (67 ± 11% of control, n = 12 to 19) and 6 h (2.4 ± 0.5 compared with 0.6 ± 0.1 of control, n = 7), respectively. Treatment with 200 μM propofol also increased cytosolic calcium concentration (346 ± 71% of control, n = 22 to 34). Propofol at 10 µM stimulated neural progenitor cell proliferation and promoted neuronal cell fate, whereas propofol at 200 µM impaired neuronal proliferation and promoted glial cell fate (n = 12 to 20). Cotreatment with ryanodine and inositol 1,4,5-trisphosphate receptor antagonists and inhibitors, cytosolic Ca2+ chelators, or autophagy inhibitors mostly mitigated the propofol-mediated effects on survival, proliferation, and differentiation. Conclusions These results suggest that propofol-mediated cell survival or neurogenesis is closely associated with propofol’s effects on autophagy by activation of ryanodine and inositol 1,4,5-trisphosphate receptors.

scholarly journals Pituitary adenylate cyclase-activating polypeptide acts synergistically with relaxin in modulating ovarian cell function in rats

2000 ◽  
Vol 167 (1) ◽  
pp. 61-69 ◽  
Author(s):  
CH Teng ◽  
FC Ke ◽  
MT Lee ◽  
SW Lin ◽  
L Chen ◽  
...  
Keyword(s):  
Adenylate Cyclase ◽  
Signaling Pathway ◽  
Granulosa Cells ◽  
Gelatin Zymography ◽  
Interstitial Cells ◽  
Camp Signaling ◽  
Matrix Metalloproteinase 2 ◽  
Ovarian Cells ◽  
Camp Signaling Pathway ◽  
Pituitary Adenylate Cyclase

The interactive effects of pituitary adenylate cyclase-activating polypeptide (PACAP) and relaxin on the secretion of gelatinases, involved in matrix remodeling, in ovarian theca-interstitial cells and granulosa cells, were investigated in gonadotropin-primed immature rats. The gelatinases secreted from cultured cells were analyzed using gelatin zymography and scanning densitometry. We have previously shown that relaxin stimulated the secretion of a 71 kDa gelatinase, identified as a type IV collagenase (matrix metalloproteinase 2), in rat theca-interstitial cells. This study has demonstrated that PACAP27 and PACAP38, with similar potency, dose-dependently enhanced relaxin-induced secretion of 71 kDa gelatinase, whereas PACAP alone had no effect. In rat granulosa cells, both PACAP27 and PACAP38 alone dose-dependently increased the secretion of a 63 kDa gelatinase. In addition, this study has shown that cAMP signaling pathway mediators act similarly to that of PACAP on gelatinase secretion in rat ovarian cells. Cholera toxin, forskolin and 8-bromoadenosine cAMP augmented relaxin-induced secretion of 71 kDa gelatinase in theca-interstitial cells, and alone they had no effect. These mediators also increased the secretion of 63 kDa gelatinase in granulosa cells. It is well known that the increase in cellular cAMP level is associated with the morphological rounding-up phenomenon in granulosa cells. This study has shown that PACAP and cAMP pathway mediators, but not relaxin, could cause such changes in cell shape in granulosa cells as well as in theca-interstitial cells. In conclusion, this study provides original findings that PACAP acts synergistically with relaxin in stimulating the secretion of gelatinases in rat ovarian theca-interstitial cells and granulosa cells. This supports the idea that relaxin and PACAP may serve as ovarian physiological mediators of gonadotropin function in facilitating the ovulatory process. In addition, PACAP appears to act through the cAMP signaling pathway to affect biological functions in ovarian cells, whereas relaxin does not.

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