Thromb Haemost 1998; 80(02): 321-325
DOI: 10.1055/s-0037-1615195
Rapid Communication
Schattauer GmbH

Evidence that Adenosine Diphosphate Can Activate Adenylate Cyclase via Conversion to Adenosine in Platelet-rich Plasma Containing Magnesium

J. R. Glenn
1   From Cardiovascular Medicine, University of Nottingham, UK
,
S. Heptinstall
1   From Cardiovascular Medicine, University of Nottingham, UK
› Author Affiliations
Further Information

Publication History

Received 19 September 1997

Accepted after resubmission 09 April 1998

Publication Date:
08 December 2017 (online)

Summary

When adenosine diphosphate (ADP) is added to hirudinized platelet-rich plasma (PRP) in which the level of platelet cAMP has been pharmacologically elevated, there is an initial rapid fall in the level of cAMP brought about by inhibition of adenylate cyclase. This may be followed by a subsequent activation of adenylate cyclase that does not occur when citrated PRP is used in place of hirudinized PRP, and is more pronounced in the presence of added Mg2+. Here we provide evidence that a) the Mg2+-dependent activation of adenylate cyclase seen in hirudinized PRP is mediated by adenosine, b) the adenosine produced synergizes with forskolin and with DN9693 to raise the level of cAMP in platelets, but not with iloprost, c) Mg2+ does not influence directly the rate or extent of cAMP production and so is more likely to influence the rate of adenosine production, and d) activation of adenylate cyclase by adenosine can lead to inhibition of platelet aggregation. ARL 66096, a P2T purinoceptor antagonist which inhibits ADP-induced platelet aggregation, prevented inhibition of adenylate cyclase by ADP. Conversely, ARL 66096 did not appear to inhibit conversion of ADP to adenosine and subsequent activation of adenylate cyclase.

 
  • References

  • 1 Cole B, Robison GA, Hartmann RC. Studies on the role of cyclic AMP in platelet function. Ann N Y Acad Sci 1971; 185: 477-87.
  • 2 Haslam RJ. Interactions of the pharmacological receptors of blood platelets with adenylate cyclase. Ser Haematol 1975; VI: 333-50.
  • 3 Hardy E, Glenn J, Heptinstall S, Rubin PC, Horn EH. Magnesium modifies the responses of platelets to inhibitory agents which act via cAMP. Thromb Haemost 1995; 74: 1132-7.
  • 4 Humphries RG, Tomlinson W, Ingall AH, Cage PA, Leff P. FPL 66096: a novel, highly potent and selective antagonist at human platelet P2T-purinoceptors. Br J Pharmacol 1994; 113: 1057-63.
  • 5 Haslam RJ, McClenaghan MD. Measurement of circulating prostacyclin. Nature 1981; 292: 364-6.
  • 6 Horn EH, Cooper J, Hardy E, Heptinstall S, Rubin PC. A cross-sectional study of platelet cyclic AMP in healthy and hypertensive pregnant women. Clin Sci 1991; 80: 549-58.
  • 7 Argawal KC, Zielinski BA, Maitra RS. Significance of plasma adenosine in the antiplatelet activity of forskolin: potentiation by dipyridamole and dilazep. Thromb Haemost 1989; 61: 106-10.
  • 8 Agarwal KC, Buckley RS, Parks Jr RE. Role of plasma adenosine in the antiplatelet action of HL 725, a potent inhibitor of cAMP phosphodiesterase: species differences. Thromb Res 1987; 47: 191-200.
  • 9 Siegel AM, Daly JW, Smith JB. Inhibition of aggregation and stimulation of cyclic AMP generation in intact human platelets by the diterpene forskolin. Mol Pharmacol 1982; 21: 680-7.
  • 10 Mokhtari A, Do Khac L, Harbon S. Forskolin alters sensitivity of the cAMP-generating system to stimulatory as well as to inhibitory agonists. A study with intact human platelets and guinea pig myometrium. Eur J Biochem 1988; 176: 131-7.
  • 11 Sutkowski EM, Tang WJ, Broome CW, Robbins JD, Seamon KB. Regulation of forskolin interactions with Type I, II, V and VI adenylyl cyclases by G . Biochemistry 1994; 33: 12852-9.
  • 12 DeLapp NW, Eckols K. Forskolin stimulation of cyclic AMP accumulation in rat brain cortex slices is markedly enhanced by endogenous adenosine. J Neurochem 1992; 58: 237-42.
  • 13 Cartmell J, Kemp JA, Alexander SPH, Kendall DA. Endogenous adenosine regulates the apparent efficacy of 1-aminocyclopentyl-1S, 3R-dicarboxylate inhibition of forskolin-stimulated cyclic AMP accumulation in rat cerebral cortical slices. J Neurochem 1993; 60: 790-2.