AJP - Cell Physiology, Vol 249, Issue 3 279-C287, Copyright © 1985 by American Physiological Society
The platelet strip. I. A low-fibrin contractile model of thrombin-activated platelets
L. Salganicoff, M. H. Loughnane, R. W. Sevy and M. Russo
The ultrastructure and contractile behavior of a new preparation of
thrombin-activated human platelets is described. The preparation is
referred to as the "platelet strip" because of its similarities to
classical vascular smooth muscle strips. The platelet strip consists of a
giant platelet aggregate 10 mm long, 4 mm wide, and 200 micron thick. To
facilitate handling, the aggregate has a special high-compliance nylon mesh
embedded in its mass. Each strip contains 7.3 X 10(8) platelets. Fibrin
contamination is 150-fold lower than in platelet-rich plasma clots. Active
isometric forces of up to 100 g/cm2 and 6-10 h viability are easily and
reproducibly obtained. Platelet strips remain contracted after thrombin
activation. The contraction is tonic and partial. Further small increases
in force can be produced by depolarizing solutions or pharmacological
agents, e.g., ADP, epinephrine, and endoperoxide analogues. These small
increases are reversible on washout of the agents. Full relaxation is
induced by agents such as prostaglandin E1 or papaverine, which increase
adenosine 3',5'-cyclic monophosphate. However, after washout of these
agents, recovery of tension is variable depending on the concentration of
the drug and the degree of prestretching of the preparation.
