Effects of various cyclooxygenase and lipoxygenase metabolites on guinea-pig cerebral arteries.

1. The effects of some prostanoids, leukotrienes, lipoxins and lipoxin precursors (15-HETE, 15-HPETE) were examined in guinea-pig isolated basilar arteries. 2. The potency order among the prostanoids to elicit contraction was U44069 greater than prostaglandin B2 greater than prostaglandin F2 alpha greater than prostaglandin E2. Leukotriene C4 and D4 were approximately equipotent with prostaglandin B2. 3. Lipoxin A4 and B4 elicited small contractions (4% of the contractile response to 124 mM K+ at 3 x 10(-6) M), which were significantly (P less than 0.02) enhanced by indomethacin. The contractile responses to 15-HETE and 15-HPETE varied considerably (2-102% and 2-56% at 3 x 10(-6) M, respectively) between different vascular segments. 4. Among the leukotrienes, lipoxins and lipoxin precursors, only lipoxin A4 elicited a relaxation, albeit small and transient. 5. In summary, all examined eicosanoids contracted the guinea-pig basilar artery, although the responses to the lipoxins were small but significantly enhanced by cyclooxygenase inhibition.