1 the content of adrenaline ( ad ) , noradrenaline ( na ) and dopamine was measured in human , guinea-pig , cat , rabbit and rat blood platelets by a highly sensitive and specific radioenzymatic method.2 in all platelet specimens analyzed , the content of the three catecholamines ( ca ) was several thousand times lower than that of 5-hydroxytryptamine ( 5-ht ) .3 in basal conditions , the na concentration in platelets and plasma always exceeded that of ad and dopamine.4 in rat and rabbit platelets , ad , na and dopamine were present only in the free ( unconjugated ) form.5 platelets of rats with storage pool deficiency ( fawn-hooded ) contained much less 5-ht and ca than normal rat platelets.6 following restraint stress , platelets of fawn-hooded rats , in contrast to normal rat platelets , did not accumulate ca in spite of a dramatic rise in plasma ca.7 reserpine , a monoamine depletor , released ca as well as 5-ht from rabbit platelets in vivo.8 subcellular fractionation experiments with rabbit platelets indicate that both ca and 5-ht are most concentrated in the fraction consisting of pure 5-ht organelles.9 both in humans and rabbits the concentration gradient between platelets and plasma was much lower for ca than for 5-ht , indicating that a high affinity transport mechanism operates in vivo for 5-ht but not for ca.10 in conclusion , the present data show that both human and animal platelets contain ad , na and dopamine .
C0014563
ad
C0028351
na