Plasmin: A possible physiological modulator of the human platelet adenylate cyclase system

1987 ◽  
Vol 72 (4) ◽  
pp. 467-473 ◽  
Author(s):  
Serge Adnot ◽  
Nicolas Ferry ◽  
Jacques Hanoune ◽  
Marie-Use Lacombe
Keyword(s):  
Platelet Aggregation ◽  
Adenylate Cyclase ◽  
Human Platelet ◽  
Inhibitory Effect ◽  
Human Platelets ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Adenylate Cyclase System ◽  
Inhibition Of Platelet Aggregation ◽  
Increased Activity

1. Plasmin was recently reported to inhibit platelet aggregation [1]. We report here on the interaction of plasmin with the adenylate cyclase system of human platelets. Human plasmin caused a dose-and time-dependent increase in adenylate cyclase activity when added to a crude platelet membrane preparation. Both basal and prostaglandin E1-stimulated adenylate cyclase activity doubled in presence of plasmin. This stimulatory activity was shared by papain and α-chymotrypsin, but not by thrombin which displayed a slightly inhibitory effect. 2. Plasmin not only stimulated platelet adenylate cyclase activity, but also suppressed the GTP-dependent α2-adrenergic inhibition, thereby producing a five- to six-fold increased activity measured in the presence of adrenaline and GTP. 3. These effects of plasmin on the adenylate cyclase system were suppressed by the addition of the protease inhibitor leupeptin, and of soybean trypsin inhibitor, indicating that proteolysis mediated these effects. 4. We also examined the adenylate cyclase activity in membranes prepared from intact platelets incubated with increasing doses of plasmin. Incubation of platelets with plasmin concentrations as low as 0.25 mg/ml resulted in an irreversible increase in membrane adenylate cyclase activity and suppression of the adrenaline-mediated inhibition of enzyme activity. 5. These results suggest that the proteolytic stimulating effect of plasmin on the platelet adenylate cyclase system may account for the inhibition of platelet aggregation.

EVIDENCE FOR A SEPARATE ADENYLATE CYCLASE SYSTEM RESPONSIVE TO BETA-ADRENERGIC STIMULATION IN THE RENAL CORTEX OF THE RAT

1974 ◽  
Vol 77 (3) ◽  
pp. 604-611 ◽  
Author(s):  
Norman H. Bell ◽  
John Fleming ◽  
Joanne Benedict ◽  
Lisa Pantzer
Keyword(s):  
Parathyroid Hormone ◽  
Adenylate Cyclase ◽  
Renal Cortex ◽  
Blocking Agent ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Adenylate Cyclase System ◽  
Adrenergic Stimulation ◽  
Beta Adrenergic ◽  
Increased Activity

ABSTRACT Previous studies in other laboratories had indicated that some of the effects of parathyroid hormone on skeletal tissue and the renal tubule to influence ion metabolism can be produced by beta-adrenergic stimulation. Studies were carried out to determine whether the same adenylate cyclase system in rat renal cortex is activated by parathyroid hormone and isoproterenol. At maximal effective concentration of dose response, parathyroid hormone (2 × −5 m) increased adenylate cyclase activity by some 415 per cent, isoproterenol (10−6 m) increased activity by some 40 to 50 per cent, vasopressin (10−5 m) increased activity by some 96 per cent and porcine calcitonin (10−5 m) increased activity by some 92 per cent. Dl-propranolol (10−5 m), a beta-adrenergic receptor blocking agent, prevented the increase in enzyme activity produced by isoproterenol (10−6 m), did not diminish the increase in activity produced by parathyroid hormone (10−6 m) and did not influence basal adenylate cyclase activity by itself. The combined maximal concentrations of isoproterenol together with either parathyroid hormone, vasopressin or porcine calcitonin were additive. These results indicate that there is an adenylate cyclase system in rat renal cortex which can be activated by beta-adrenergic stimulation with isoproterenol, and is separate from the systems responsive to parathyroid hormone, vasopressin or calcitonin.

Inhibitory effect of ristocetin and factor VIII/von Willebrand factor protein on human platelet adenylate cyclase activity

1983 ◽  
Vol 30 (3) ◽  
pp. 301-308 ◽  
Author(s):  
Kuo-Jang Kao ◽  
Bie-Shung Tsai ◽  
Patrick A. McKee ◽  
Robert J. Lefkowitz ◽  
Salvatore V. Pizzo
Keyword(s):  
Adenylate Cyclase ◽  
Factor Viii ◽  
Von Willebrand Factor ◽  
Human Platelet ◽  
Inhibitory Effect ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Von Willebrand ◽  
Willebrand Factor

Effects of benzyl alcohol on PTH receptor-adenylate cyclase system of canine kidney

1985 ◽  
Vol 248 (1) ◽  
pp. E31-E35
Author(s):  
K. J. Martin ◽  
C. L. McConkey ◽  
T. J. Stokes
Keyword(s):  
Enzyme Activity ◽  
Adenylate Cyclase ◽  
Benzyl Alcohol ◽  
Membrane Fluidity ◽  
Phospholipid Composition ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Adenylate Cyclase System ◽  
Hormone Sensitive ◽  
Canine Kidney

In many systems, perturbations of membrane architecture by changes of lipid and phospholipid composition have been shown to alter the activity of membrane-bound enzymes. The present studies examined the effect of benzyl alcohol, an agent that has been shown to increase membrane fluidity, on the parathyroid hormone (PTH)-sensitive adenylate cyclase system of canine kidney. Benzyl alcohol progressively increased basal adenylate cyclase activity up to fourfold and maximal enzyme activity in the presence of PTH, GTP, guanylimidodiphosphate, and sodium fluoride by four- to sixfold. In the presence of 20 mM Mn2+ (no Mg2+), conditions under which enzyme activity is devoid of influence of guanine nucleotides or hormones, benzyl alcohol was without effect. PTH binding was increased by 25% in the presence of benzyl alcohol without a change in binding affinity. Fluorescent polarization studies using diphenylhexatriene showed a decrease in fluorescence anisotropy in the presence of benzyl alcohol. The results suggest that benzyl alcohol facilitates the interaction of the components of the adenylate cyclase system, presumably by increasing membrane fluidity. Alterations of membrane fluidity may be a potent means of regulating hormone sensitive adenylate cyclase activity.

scholarly journals Evidence for regulation of human platelet adenylate cyclase by phosphorylation. Inhibition by ATP and guanosine 5′-[β-thio]diphosphate occur by distinct mechanisms

1991 ◽  
Vol 276 (3) ◽  
pp. 621-630 ◽  
Author(s):  
I A Wadman ◽  
R W Farndale ◽  
B R Martin
Keyword(s):  
Creatine Kinase ◽  
Adenylate Cyclase ◽  
Human Platelet ◽  
Binding Protein ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Phosphoryl Transfer ◽  
Activation Process ◽  
Gtp Binding Protein ◽  
Gtp Binding

1. Incubation of human platelet membranes with guanosine 5′-[beta gamma-imido]triphosphate (p[NH]ppG) causes a time-dependent increase in the activation of adenylate cyclase due to Gs (the stimulatory GTP-binding protein). Forskolin enhances adenylate cyclase activity but does not interfere with the process of activation. The activation follows first-order kinetics in both the presence and the absence of the assay components. 2. ATP in the presence or the absence of an ATP-regenerating system of phosphocreatine and creatine kinase inhibits activation. 3. Hydrolysis of ATP to ADP does not lead to receptor-mediated inhibition of adenylate cyclase acting via Gi (the inhibitory GTP-binding protein). The ADP analogue adenosine 5′-[beta-thio]diphosphate (ADP[S]) does not inhibit the activation process. 4. Phosphocreatine alone inhibits adenylate cyclase activation at concentrations above 1 mM. 5. Inhibition by phosphocreatine is not due to the chelation of free Mg2+ ions. 6. Inhibition by ATP and the other assay components occurs throughout the activation process, decreasing both the rate of activation and the maximum activity obtained. 7. Maximal activation of adenylate cyclase after prolonged incubation with p[NH]ppG slowly reverses in the presence of the assay components. 8. A 10-fold excess of the GDP analogue guanosine 5′-[beta-thio]diphosphate (GDP[S]) over p[NH]ppG inhibits the activation process completely, at all stages of the time course. 9. Preincubations in the presence and absence of ATP, cyclic AMP, phosphocreatine and creatine kinase show equal sensitivity to increasing GDP[S] concentration. These data show that the inhibition observed in the presence of ATP is not due to endogenous or contaminating guanine nucleotides, and suggest that phosphoryl transfer may regulate adenylate cyclase activity.

Calmodulin regulation of adenylate cyclase activity in human platelet membranes

Cell Calcium ◽  
1986 ◽  
Vol 7 (4) ◽  
pp. 261-273 ◽  
Author(s):  
George Y. Grigorian ◽  
Therese J. Resink ◽  
Susanne Stucki ◽  
Fritz R. Bühler
Keyword(s):  
Adenylate Cyclase ◽  
Human Platelet ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Platelet Membranes

Temporal effects of cytokines on neonatal cardiac myocyte Ca2+ transients and adenylate cyclase activity

1997 ◽  
Vol 272 (4) ◽  
pp. H1937-H1944 ◽  
Author(s):  
R. J. Bick ◽  
J. P. Liao ◽  
T. W. King ◽  
A. LeMaistre ◽  
J. B. McMillin ◽  
...  
Keyword(s):  
Adenylate Cyclase ◽  
Cardiac Myocyte ◽  
Prolonged Exposure ◽  
Neonatal Rat ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Short Exposure ◽  
Adenylate Cyclase System ◽  
Long Term Treatment

This study investigates the hypothesis that inflammatory cytokines, interleukin (IL)-1alpha IL-1beta, and tumor necrosis factor (TNF), influence cardiac function by affecting calcium homeostasis and that this effect is mediated by the beta-adrenergic-adenylate cyclase system. After 4 days in culture, neonatal rat ventricular myocytes were treated with cytokines (10 ng/ml) for short (2 h) or longer (18 h) times. Myocyte calcium, contractility, and adenylate cyclase were measured under each condition. Anticipated stepwise increases in adenylate cyclase and intracellular calcium were found in controls (non-cytokine-treated) with 10(-7) M isoproterenol, 10(-7) M isoproterenol + 0.1 mM guanosine triphosphate, and 10(-9) M forskolin. Cells in the presence of cytokine for 2 h show increased basal calcium levels but no changes in adenylate cyclase activities, and isoproterenol fails to elevate adenylate cyclase levels or affect contractile shortening. After long-term treatment with IL-1beta or TNF, but not IL-1alpha, the significantly elevated levels of basal systolic calcium remain, and isoproterenol increases adenylate cyclase activity, unlike after short exposure. Forskolin maximally activates adenylate cyclase following both short- and long-term incubation, but the stepwise increase in activity is blunted following prolonged exposure. Thus short-term cytokine treatment blocks the adrenergic receptor-mediated increases in adenosine 3',5'-cyclic monophosphate, dissociating adenylate cyclase activation from cytokine-mediated increases in cell calcium, whereas longer treatment apparently produces direct affects on adenylate cyclase. Time-dependent differences in contractile response were found with IL-1alpha at 2 h and TNF at 18 h, implying that myofibrillar responsiveness to increased cytoplasmic calcium is dependent on both cytokine species and exposure time.

Dipyridamole (D) Reduces the Effectiveness of Prostaglandin (PG) I2. PGD2 and PGE1 as Inhibitors of Platelet Aggregation in Human Platelet-Rich Plasma (PRP)

1979 ◽  
Author(s):  
Di G. Minno ◽  
de G. Gaetano ◽  
M.J. Silver
Keyword(s):  
Platelet Aggregation ◽  
Inhibitory Concentration ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Inhibitory Effect ◽  
Mechanisms Of Action ◽  
Phosphodiesterase Activity ◽  
Inhibition Of Platelet Aggregation ◽  
Normal Humans ◽  
The Mean

The effectiveness and the mechanism of action of D as an anti-thrombotic agent has been controversial. It has been proposed that D works by potentiating the inhibitory activity of "circulating" PGE2 on platelet aggregation by inhibiting platelet phosphodiesterase activity. To determine whether such potentiation exists in normal humans we studied inhibition of aggregation by the PGs in PRP before and 90 mln after the ingestion of D (100 mg). As expected, we found that the threshold aggregating concentrations of ADP, collagen and arachidonic acid (AA) were unchanged after the ingestion of D. Unexpectedly, the threshold inhibitory concentration of each PG was greater after ingestion of D than before. The mean elevations for PGI2 were 8.8 nM (p<0.05) vs ADP; 9.1 nM(p<0 01) ys collagen; 9.2 nM (p<0.001) vs AA; for FCD2 14.5 nM (p<0.05) vs AA; for PGE, 69 0 nM (p<0.05) vs collagen and 25.9 nM (p<0.05) vs AA. The elevations for PGD2 vs ADP and collagen and for PGE1 vs ADP were not significant. These data do not support the hypothesis that D aces as an anti-thrombotic agent by potentiating the inhibition of platelet aggregation by “circulating” PGIZ. The findings show that ingestion of D Interferes with the inhibitory effect of the PGs and suggest that other mechanisms of action ot D should be investigated.(Supported by the Italian CNR and NIH).

Increased phosphatidic acid and decreased lysophosphatidic acid in response to thrombin is associated with inhibition of platelet aggregation

1993 ◽  
Vol 71 (9-10) ◽  
pp. 432-439 ◽  
Author(s):  
Jon M. Gerrard ◽  
Pauline Robinson ◽  
Michael Narvey ◽  
Archibald McNicol
Keyword(s):  
Platelet Aggregation ◽  
Phosphatidic Acid ◽  
Lysophosphatidic Acid ◽  
Human Platelet ◽  
Inhibitory Effect ◽  
Phospholipase A ◽  
Direct Role ◽  
Inhibition Of Platelet Aggregation ◽  
Phosphatidate Phosphohydrolase ◽  
Rule Out

Thromboxane A2, produced from the arachidonic acid released from platelet phospholipids by phospholipase A2, stimulates platelet aggregation. It remains unresolved whether additional products of platelet phospholipase A2 might promote aggregation. To address this question, we have used aspirin-treated platelets to block thromboxane A2 formation and studied the influence of the phospholipase A2 inhibitor U10029A on platelet aggregation and secretion in response to thrombin. U10029A at 100 μM markedly inhibited platelet aggregation, but had no effect on platelet secretion. Since this concentration of U10029A effectively blocked lysophosphatidic acid (LPA) formation, LPA was added and found to substantially reverse the inhibitory effect of U10029A in these platelets. Furthermore, the action of U10029A was not due to inhibition of phosphatidate phosphohydrolase because U10029A, unlike propranolol, did not inhibit this enzyme. Although it is not possible to conclusively rule out an effect of U10029A in addition to its inhibition of phospholipase A2, our results reveal that a product of phospholipase A2 other than thromboxane A2 is important for platelet aggregation, but not for secretion in response to thrombin. Our data suggest that this product is LPA. Since the amount of phosphatidic acid (PA) increased dramatically concurrent with inhibition of platelet aggregation, it is safe to conclude that PA has no direct role to promote platelet aggregation in response to thrombin.Key words: lysophosphatidic acid, phosphatidic acid, phospholipase A2, human platelet.

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