The synthesis of prostaglandins by bovine cerebral microvessels

Bovine cerebral microvessels (arterioles and capillaries) synthesize prostacyclin (PGI₂, measured as 6-keto PGF_1α), PGF_2α, PGE₂ and thromboxane A₂ (measured as TXB₂) when incubated in glucose-bicarbonate buffer for 30 minutes. Rapid freezing and thawing decreased the subsequent synthesis of 6-keto PGF_1α by cerebral microvessels and raised the basal levels of this metabolite within the incubation medium. At low concentrations, the addition of arachidonic acid (0.16 μM) did not stimulate prostacyclin or prostaglandin production; at higher concentrations (16 μM), the synthesis of PGI₂ and PGF_2α was inhibited. Activation of lipase by the peptide melittin stimulated the synthesis of all arachidonic acid metabolites to the same extent. Thus cerebral microvessels deacylate cellular lipids and metabolize endogenous arachidonic acid to form prostaglandins, prostacyclin and related compounds as previously demonstrated in larger blood vessels. The synthesis and release of these molecules may be important for modulating the tone and reactivity of small blood vessels within the brain.