Activation of adenylate cyclase in cultured fibroblasts by trypsin.

Many studies previously have shown that the B-adrenergic agonist isoproterenol and the a-adrenergic agonist norepinephrine will stimulate secretion by the adult rat submandibular (SMG) and parotid glands. Recent data from several laboratories indicates that adrenergic agonists bind to specific receptors on the secretory cell surface and stimulate membrane associated adenylate cyclase activity which generates cyclic AMP. The production of cyclic AMP apparently initiates a cascade of events which culminates in exocytosis. During recent studies in our laboratory it was observed that the adenylate cyclase activity in plasma membrane fractions derived from the prenatal and early neonatal rat submandibular gland was retractile to stimulation by isoproterenol but was stimulated by norepinephrine. In addition, in vitro secretion studies indicated that these prenatal and neonatal glands would not secrete peroxidase in response to isoproterenol but would secrete in response to norepinephrine. In contrast to these in vitro observations, it has been shown that the injection of isoproterenol into the living newborn rat results in secretion of peroxidase by the SMG (1).

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Intralysosomal Accumulation of Colloidal Gold-Low Density Lipoprotein Conjugates in Chloroquine-Treated Fibroblasts

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010011951x ◽

1985 ◽

Vol 43 ◽

pp. 546-547 ◽

Cited By ~ 1

Author(s):

Dean A. Handley ◽

Cynthia M. Arbeeny ◽

Larry D. Witte

Keyword(s):

Colloidal Gold ◽

Cultured Cells ◽

Low Density Lipoprotein ◽

Density Lipoprotein ◽

Coated Vesicle ◽

Low Density ◽

Cholesterol Esters ◽

Cultured Fibroblasts ◽

Surface Receptors ◽

Ldl Particles

Low density lipoproteins (LDL) are the major cholesterol carrying particles in the blood. Using cultured cells, it has been shown that LDL particles interact with specific surface receptors and are internalized via a coated pit-coated vesicle pathway for lysosomal catabolism. This (Pathway has been visualized using LDL labeled to ferritin or colloidal gold. It is now recognized that certain lysomotropic agents, such as chloroquine, inhibit lysosomal enzymes that degrade protein and cholesterol esters. By interrupting cholesterol ester hydrolysis, chloroquine treatment results in lysosomal accumulation of cholesterol esters from internalized LDL. Using LDL conjugated to colloidal gold, we have examined the ultrastructural effects of chloroquine on lipoprotein uptake by normal cultured fibroblasts.

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Enhancement of matrix metalloproteinase (MMP)‐2 activity in gingival tissue and cultured fibroblasts from Down's syndrome patients

Oral Diseases ◽

10.1034/j.1601-0825.2001.0070110.x ◽

2001 ◽

Vol 7 (1) ◽

pp. 47-55 ◽

Cited By ~ 1

Author(s):

T Komatsu ◽

E Kubota ◽

N Sakai

Keyword(s):

Matrix Metalloproteinase ◽

Down's Syndrome ◽

Down’S Syndrome ◽

Gingival Tissue ◽

Cultured Fibroblasts

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Opiate-Inhibited Adenylate Cyclase in Mammalian Brain Membranes

PsycEXTRA Dataset ◽

10.1037/e496832006-005 ◽

1986 ◽

Cited By ~ 1

Author(s):

Steven R. Childers ◽

Peter Nijssen ◽

Pauline Nadeau ◽

Page Buckhannan ◽

Phi-Van Le ◽

...

Keyword(s):

Adenylate Cyclase ◽

Mammalian Brain ◽

Brain Membranes

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Anti-viral protection conferred by recombinant adenylate cyclase toxins from Bordetella pertussis carrying a CD8+ T cell epitope from LCMV

Immunology Letters ◽

10.1016/s0165-2478(97)88019-4 ◽

1997 ◽

Vol 56 (1-3) ◽

pp. 293

Author(s):

M Saron

Keyword(s):

T Cell ◽

Adenylate Cyclase ◽

Bordetella Pertussis ◽

Cell Epitope ◽

Cd8 T Cell ◽

T Cell Epitope

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Ticlopidine and Clopidogrel (SR 25990C) Selectively Neutralize ADP Inhibition of PGE1-Activated Platelet Adenylate Cyclase in Rats and Rabbits

Thrombosis and Haemostasis ◽

10.1055/s-0038-1647481 ◽

1991 ◽

Vol 65 (02) ◽

pp. 186-190 ◽

Cited By ~ 61

Author(s):

G Defreyn ◽

C Gachet ◽

P Savi ◽

F Driot ◽

J P Cazenave ◽

...

Keyword(s):

Platelet Aggregation ◽

Adenylate Cyclase ◽

Direct Effect ◽

Cyclic Nucleotide ◽

Camp Accumulation ◽

Rabbit Platelets ◽

Camp Levels ◽

Kinetics Of ◽

Camp Elevation ◽

Rat Platelets

SummaryTiclopidine and its potent analogue, clopidogrel, are powerful inhibitors of ADP-induced platelet aggregation. In order to improve the understanding of this ADP-selectivity, we studied the effect of these compounds on PGE1-stimulated adenylate cyclase and on the inhibition of this enzyme by ADP, epinephrine and thrombin. Neither drug changed the basal cAMP levels nor the kinetics of cAMP accumulation upon PGEj-stimulation in rat or rabbit platelets, which excludes any direct effect on adenylate cyclase or on cyclic nucleotide phosphodiesterase. However, the drop in cAMP levels observed after addition of ADP to PGEr stimulated control platelets was inhibited in platelets from treated animals. In contrast, the drop in cAMP levels produced by epinephrine was not prevented by either drug in rabbit platelets. In rat platelets, thrombin inhibited the PGEX-induced cAMP elevation but this effect seems to be entirely mediated by the released ADP. Under these conditions, it was not surprising to find that clopidogrel also potently inhibited that effect of thrombin on platelet adenylate cyclase. In conclusion, ticlopidine and clopidogrel selectively neutralize the ADP inhibition of PGEr activated platelet adenylate cyclase in rats and rabbits.

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The Increased Sensitivity of Platelets to Prostacyclin in Marathon Runners

Thrombosis and Haemostasis ◽

10.1055/s-0038-1661107 ◽

1984 ◽

Vol 51 (03) ◽

pp. 385-387 ◽

Cited By ~ 8

Author(s):

Clive J Dix ◽

David G Hassall ◽

K Richard Bruckdorfer

Keyword(s):

Cardiovascular Disease ◽

Endothelial Cells ◽

Platelet Aggregation ◽

Cyclic Amp ◽

Adenylate Cyclase ◽

Platelet Rich Plasma ◽

Marathon Runners ◽

Inhibition Of Platelet Aggregation ◽

Increased Sensitivity ◽

Membrane Bound

SummaryPlatelet-rich plasma was obtained 24 hr after the race ended from athletes who ran in the London marathon. The platelets were only marginally less sensitive to adrenaline than were those of non-runners using conventional aggregation tests. However, the runners’ platelets were much more sensitive to inhibition by prostacyclin, a prostaglandin synthesized by endothelial cells. It appeared that this effect was due to a greater activity in the platelets of the membrane-bound adenylate cyclase enzyme which generates intracellular cyclic AMP. Cyclic AMP production is known to be stimulated by prostacyclin and to cause the inhibition of platelet aggregation. The results indicate another possible protective effect of exercise against cardiovascular disease which is independent of the known changes in lipoprotein concentrations previously observed in athletes.

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Epinephrine Induces von Willebrand Factor Release from Cultured Endothelial Cells: Involvement of Cyclic AMP-dependent Signalling in Exocytosis

Thrombosis and Haemostasis ◽

10.1055/s-0038-1656135 ◽

1997 ◽

Vol 77 (06) ◽

pp. 1182-1188 ◽

Cited By ~ 74

Author(s):

Ulrich M Vischer ◽

Claes B Wollheinn

Keyword(s):

Endothelial Cells ◽

Adenylate Cyclase ◽

Von Willebrand Factor ◽

Umbilical Vein ◽

Free Calcium ◽

Camp Content ◽

Von Willebrand ◽

Willebrand Factor

Summaryvon Willebrand factor (vWf) is released from endothelial cell storage granules after stimulation with thrombin, histamine and several other agents that induce an increase in cytosolic free calcium ([Ca2+]i). In vivo, epinephrine and the vasopressin analog DDAVP increase vWf plasma levels, although they are thought not to induce vWf release from endothelial cells in vitro. Since these agents act via a cAMP-dependent pathway in responsive cells, we examined the role of cAMP in vWf secretion from cultured human umbilical vein endothelial cells. vWf release increased by 50% in response to forskolin, which activates adenylate cyclase. The response to forskolin was much stronger when cAMP degradation was blocked with IBMX, an inhibitor of phosphodiesterases (+200%), whereas IBMX alone had no effect. vWf release could also be induced by the cAMP analogs dibutyryl-cAMP (+40%) and 8-bromo-cAMP (+25%); although their effect was weak, they clearly potentiated the response to thrombin. Epinephrine (together with IBMX) caused a small, dose-dependent increase in vWf release, maximal at 10-6 M (+50%), and also potentiated the response to thrombin. This effect is mediated by adenylate cyclase-coupled β-adrenergic receptors, since it is inhibited by propranolol and mimicked by isoproterenol. In contrast to thrombin, neither forskolin nor epinephrine caused an increase in [Ca2+]j as measured by fura-2 fluorescence. In addition, the effects of forskolin and thrombin were additive, suggesting that they act through distinct signaling pathways. We found a close correlation between cellular cAMP content and vWf release after stimulation with epinephrine and forskolin. These results demonstrate that cAMP-dependent signaling events are involved in the control of exocytosis from endothelial cells (an effect not mediated by an increase in [Ca2+]i) and provide an explanation for epinephrine-induced vWf release.

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