Coulter Counter and light transmission studies of platelets exposed to low temperature, ADP, EDTA, and storage at 22 degrees
Holme, S.; Murphy, S.
Journal of Laboratory and Clinical Medicine 96(3): 480-493
1980
ISSN/ISBN: 0022-2143 PMID: 6772721 Document Number: 168339
Changes in apparent platelet mean volume (V) as determined by Coulter Counter were compared with changes in light transmission properties of platelets in plasma when the platelets were exposed to low temperature, ADP, EDTA or storage for transfusion at 22.degree. C. Two light transmission parameters were determined. One was recently described; it measures the shape change of the platelets. The other was quantitated as the average extinction (optical density) per platelet (e). With fresh PRP from 29 normal donors a strong positive correlation (r = 0.90) was found between e and V; thus e appears to reflect the volume of the platelets. When varying degrees of shape change were produced by exposure of citrated PRP to low temperatures or ADP, there was a linear correlation between percent shape change and the percent increase in V and e. A complete shape change as produced by 10 .mu.M ADP increased e and V 19 and 24%, respectively. Spherical platelets obtained from blood anticoagulated with EDTA showed an increase in V that exceeded what could be produced by shape change alone and an associated decrease in e when compared with platelets in citrated plasma. This change progressed as hours passed after blood collection. Light-scattering theory would predict this if cellular swelling occurs. The extinction measurements were then applied, complemented with Coulter volume determinations, to the study of platelet morphology during storage for transfusion at 22.degree. C. Platelet concentrates with high platelet counts stored in containers constructed of polyvinylchloride are exposed to hypoxic conditions which lead to accelerated glycolysis, pH fall and platelet shape change. As the platelet concentrate pH fell below 6.7, there was a progressive increase in V beyond what could be accounted for by shape change and a proportionate decrease in e. This swelling may reflect the inability of the platelets to maintain normal intracellular volume under hypoxic stress. There 3 measurements are objective, quantitative and complementary; they reflect platelet morphology and can be used in the study of in vitro platelet behavior.