Summary
The role of dietary copper deficiency in platelet-to-endothelial cell adhesion and
in platelet-to-platelet aggregation was studied in vitro. Platelets were obtained
from male, weanling Sprague-Dawley rats fed purified diets which were either copper-adequate
(CuA, 6.3 μg copper/g of diet) or copper-deficient (CuD, 0.3 μg copper/g of diet)
for 4 weeks. The platelet adhesion study was performed by adding CuA or CuD platelets
either suspended in homologous plasma or in Tyrode buffer salt solution (TBSS) to
cultured rat endothelial cells. After a one hour incubation at 37° C non-adhered platelets
were removed and counted in a microcytometer. Platelet aggregation in platelet rich
plasma (PRP) samples was induced by adding ADP (2 × 10−4 M) and measured in a turbidometric platelet aggregometer. The content of von Willebrand
factor (vWF) in platelets and in plasma and the content of fibrinogen in platelets
was determined. Platelet adhesion to rat endothelial cells was significantly lower
for platelets from CuD rats than for platelets from CuA rats. ADP induced platelet
aggregation from CuD rats was significantly higher than platelet aggregation from
CuA rats. The content of vWF in platelets and in plasma from CuD rats was significantly
lower than in platelets and plasma from CuA rats. However, the amount of fibrinogen
in platelets from CuD rats was about 4-fold higher than that in platelets from CuA
rats while the plasma fibrinogen was lower in CuD rats than in CuA rats. These studies
illustrate that copper deficiency diminishes platelet adhesion to endothelial cells
but increases platelet aggregability. The results suggest that these physiological
alterations may be the result of decreased platelet vWF and increased platelet fibrinogen
during dietary copper deficiency.
