Modification of Platelet Sulfhydryl Groups

Summary

Sulfhydryl (SH) reagents are known to inhibit platelet aggregation but their effect on the release reaction has not been systematically studied. To delineate the functional effect of penetrating versus nonpenetrating SH inhibitors, we studied primary and secondary aggregation, the collagen and thrombin induced release reaction and clot retraction. Washed human platelets were used to avoid exposing plasma proteins and added reagents to SH inhibitors. We found that 5,5´ dithiobis (2 nitrobenzoic acid) interacted only with superficially-located SH groups which were not essential for either aggregation, the release reaction, clot retraction, or membrane stability. N-ethylmaleimide at low concentrations was found to interact in rapid succession with SH groups essential for aggregation, clot retraction, and the release reaction. Finally, at very much larger concentration, it may have interacted with a structural SH group. P-hydroxymercuriphenyl sulfonate presented a very complex pattern. At low concentrations it appeared to interfere with the free access to the platelet surface of externally-added agents. At higher concentrations, it interacted first with SH groups associated with aggregation, and then with SH groups associated with clot retraction. Finally, it appeared to interfere with structural SH groups, producing a membrane leak of proteins and nucleotides. The release reaction was never specifically inhibited.

• References

• 1 Aledort L. M, Troup S. B, Weed R. I. Inhibition of sulfhydryldependent platelet functions by penetrating and nonpenetrating analogues of parachloro mercuri- benzine. Blood 1968; 31: 471
• 2 Al-Mondhiry H, Spaet T. H. Inhibition of platelet adhesion to collagenby sulfhydryl inhibitors. Proceedings of the Society for Experimental Biology andMedicine 1970; 135: 878
• 3 Ball G, Fulwood M, Ireland D. M, Yates P. Effect of some inhibitorsof platelet aggregation on platelet nucleotides. Biochemical Journal 1969; 114: 669
• 4 Born G. V. R, Gellson R. E. Studies on the uptake of 5-hydroxytryptamine by blood platelets. Journal of Physiology 1959; 146: 472
• 5 Brinson K. Effect of sulfhydryl inhibitors and membrane-active drugs on platelet reactions. Atherosclerosis 1973; 17: 139
• 6 Davey M. G, Lüscher E. F. Release reactions of human platelet induced by thrombin and other agents. Biochimica et Biophysica Acta 1968; 165: 490
• 7 Day H. J, Holmsen H. Concepts of the blood platelet release reaction. Series Haematologica 1971; IV: 3
• 8 Ellman G. L. Tissue sulfhydryl groups. Archives of Biochemistry and Biophysics 1959; 82: 70
• 9 Fantl P. Thiol groups of blood platelets in relation to clot retraction. Nature 1963; 198: 85
• 10 Godin D. V, Schrier S. L. Modification of the erythrocyte membrane by sulfhydryl group reagents. Journal of Membrane Biology 1972; 7: 285
• 11 Harbury C. B, Hershgold J. E, Schrier S. L. Requirements for aggregation of washed human platelets suspended in buffered salt solutions. Thrombosis et Diathesis Haemorrhagica 1972; 28: 2
• 12 Harrison M. J. G, Emmons P. R, Mitchell J. R. A. The effect of sulfhydryl and enzyme inhibitors on platelet aggregation in vitro. Thrombosis et Diathesis Haemorrhagica 1966; 16: 122
• 13 Holmsen H, Day H. J, Stormorken H. The blood platelet release reaction. Scandinavian Journal of Haematology Supplement 1969; 8: 1
• 14 Jacob H. S, Jandl J. H. Effects of sulfhydryl inhibition on red cells, I. Mechanism of hemolysis. Journal of Clinical Investigation 1962; a 41: 779
• 15 Jacob H. S, Jandl J. H. Effects of sulfhydryl inhibition on red cells, II. Studies in vivo. Journal of Clinical Investigation 1962; b 41: 779
• 16 Koppel J. L, Novak L. V, Olwin J. H. Relation between platelet integrityand sulfhydryl groups. Proceedings of the Society for Experimental Biology and Medicine 1959; 100: 227
• 17 Loftfield R. B, Eigner E. A. Molecular order of participation of inhibitors in biological systems. Science 1969; 164: 305
• 18 Massini P, Lüscher E. F. The induction of the release reaction in human blood platelets by close cell contact. Thrombosis et Diathesis Haemorrhagica 1971; 25: 13
• 19 Murer E.H, Holme R. A study of the release of calcium from human blood platelets and its inhibition by metabolic inhibitors, N-ethyl maleimide and aspirin. Biochimica et Biophysica Acta 1970; 222: 197
• 20 Pletscher A. Metabolism, transfer and storage of 5-hydroxytryptamine in blood platelets. British Journal of Pharmacology 1968; 32: 1
• 21 Robinson Jr. D. W, Mason R. G, Wagner R. H. Effect of sulfhydryl inhibitors on platelet agglutinability. Proceedings of the Society for Experimental Biology and Medicine 1963; 113: 857
• 22 Robinson Jr. C. W, Kress S. C, Wagner R. H, Brinkhous K. M. Platelet agglutination and deagglutionation with a sulfhydryl inhibitor methyl mercuric nitrate: Relationship to platelet ATPase. Experimental and Molecular Pathology 1965; 4: 457
• 23 Sano I, Kakimoto Y, Taniguchi K. Binding and transport of serotonin in rabbit blood platelets and action of reserpine. American Journal of Physiology 1958; 195: 495
• 24 Skalhegg B. A, Hellem A. J, Odegaard A. E. Investigations on adenosine diphosphate induced platelet adhesiveness in vitro. Thrombosis et Diathesis Haemorrhagica 1964; 11: 305