Inhibition of rat platelet aggregation by a Prudhoe Bay crude oil and its aliphatic, aromatic, and heterocyclic fractions.

Washed platelets isolated from rats 24 hr after oral treatment with a Prudhoe Bay crude oil (PBCO) showed a substantial inhibition of aggregation induced by ADP, arachidonic acid, or epinephrine. In vitro addition of a dimethyl sulfoxide extract of PBCO or its aliphatic, aromatic, or heterocyclic fractions to washed platelets also resulted in an inhibition of aggregation. ADP release was inhibited in platelets to which an extract of PBCO or its fractions were added in vitro or in platelets isolated from rats treated in vivo with PBCO. Thromboxane B2 release was increased in platelets isolated from rats intubated with PBCO or in platelets to which a dimethyl sulfoxide extract of the aromatic or heterocyclic fraction was added. However, thromboxane B2 release was inhibited in platelets to which PBCO or the aliphatic fraction extracts were added. The results indicate that PBCO inhibits platelet aggregation presumably by bringing about alterations in the platelet plasma membrane. Inhibition of ADP release could contribute to the inhibition of aggregation but thromboxane B2 is believed not to play a significant role.