Summary
The ADP-induced aggregation of human platelets is markedly increased after preincubation
with lithiumchloride, whereas lithium has the opposite effect on rabbit platelets.
Since this phenomenon might be related to cAMP metabolism, the influence of lithium
on total cAMP content and adenylate cyclase activity was investigated. Lithium does
not significantly change the total cAMP content of human platelets neither during
incubation nor during ADP-induced aggregation. Basal adenylate cyclase activity, however,
was slightly inhibited by lithium in human platelets. The inhibition of adenylate
cyclase by ADP appeared to be enhanced by lithium. Prostacyclin induced stimulation
of adenylate cyclase is counteracted by this ion.
In rabbit platelets the prostacyclin stimulated adenylate cyclase activity is not
affected by lithium.
These data suggest that a correlation exists between the influence of lithium on the
aggregation of human and rabbit platelets and the sensitivity of their adenylate cyclase
for this ion.
Keywords
Platelets - Lithium - Adenylate cyclase - Aggregation
