The State of Actin Polymerization in Tetracaine-Treated Platelets

Summary

Although there is considerable evidence that platelet activation is associated with polymerization of actin, it is not known whether there is some pre-existing F-actin even before activation. We have examined the state of actin polymerization in nonactivated platelets by deoxyribonuclease assay of G-actin and total actin. To fully suppress activation, platelets were prepared in the presence of tetracaine. The G-actin/total actin ratio in tetracaine-treated platelets prepared by three different methods is significantly less than one (average of all results = 0.61). We conclude that about 39% of total actin in nonactivated tetracaine-treated platelets may be present as F-actin.

Keywords

Actin polymerization - Tetracaine-treated platelets

• References

• 1 Nachmias VT. Cytoskeleton of human platelets at rest and after spreading. J Cell Biol 1980; 86: 795-802
• 2 Carlsson L, Markey F, Blikstad I, Persson T, Lindberg U. Reorganization of actin in platelets stimulated by thrombin as measured by the DNase inhibition assay. Proc Nat Acad Sci USA 1979; 76: 6376-6380
• 3 Phillips DR, Jennings LK, Edwards HH. Identification of membrane proteins mediating the interaction of human platelets. J Cell Biol 1980; 86: 77-86
• 4 Gonnella PA, Nachmias VT. Platelet activation and microfilament bundling. J Cell Biol 1981; 89: 146-151
• 5 Jennings LK, Fox JEB, Edwards HH, Phillips DR. Changes in the cytoskeletal structure of human platelets following thrombin activation. J Biol Chem 1981; 256: 6927-6932
• 6 Markey F, Persson T, Lindberg U. Characterization of platelet extracts before and after stimulation with respect to the possible role of profilactin as microfilament precursor. Cell 1981; 23: 145-153
• 7 Blikstad I, Markey F, Carlsson L, Persson T, Lindberg U. Selective assay of monomeric and filamentous actin in cell extracts, using inhibition of deoxyribonuclease I. Cell 1978; 15: 935-943
• 8 Nachmias VT, Sullender J, Asch A. Shape and cytoplasmic filaments in control and lidocaine-treated human platelets. Blood 1977; 50: 39-53
• 9 Nachmias VT, Sullender JS, Fallon JR. Effects of local anesthetics on human platelets: filopodial suppression and endogenous proteolysis. Blood 1979; 53: 63-72
• 10 Timmons S, Hawiger J. Separation of human platelets from plasma proteins including factor VIII_VWF by a combined albumin gradient-gel filtration method using Hepes buffer. Thromb Res 1978; 12: 297-306
• 11 Laemmli UK. Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature 1970; 227: 680-685
• 12 Adelstein RS, Pollard TD. Platelet contractile proteins. Prog Hemostasis Thromb 1978; 4: 37-58
• 13 Goldstein A. Biostatistics: An Introductory Text. Macmillan; New York: 184-187 1964
• 14 Pollard TD. Cytoskeletal functions of cytoplasmic contractile proteins. J Supramol Struct 1976; 5: 317-334
• 15 Oosawa F, Kasai M. Actin. In: Timasheff SM, Fasman GD. (Eds) Subunits in Biological Systems. 261-322 Dekker; New York: 1971
• 16 Wang L, Bryan J. Isolation of calcium-dependent platelet proteins that interact with actin. Cell 1981; 25: 637-649