Optimal Efficiency of Human Platelet Shape Changes

Abstract

The light scattering extinction coefficients and kinetic rate constant(s) for the disc to sphere and the sphere to (smaller) ‘spiny sphere’ shape changes induced in platelets by saturating amounts of ADP are compared at 31, 37 and 41 °C. Platelets exhibit optimum efficiency at 37 °C, as judged by not only the rates of the shape changes but also by alterations in the overall sizes and shapes of the three platelet forms. Unstimulated (discoid) platelets appear to be flatter at 37 °C, the disc to sphere reaction appears to be impaired at other than 37 °C, and the pseudopodia which characterize the final spiny sphere may be more prominent at 41 °C.

Platelet activation in normo- and hyperlipoproteinemias

“…Recently, it could be demonstrated by stopped-flow laser turbidimetry, that the first morphological event upon stimulation of platelets is a swelling to form spherical cells (56,61). These spherical cells are intermediates with a half lifetime of 5-6 sec and convert to spiny spheres, which form long pseudopodia.…”