Biological activities of lipoxin A include lung strip contraction and dilation of arterioles in vivo.
Lipoxin A ([5S,6R,15S]-5,6,15-trihydroxy-7,9,13-trans-11-cis-eicosatetraenoic acid), a recently characterized lipoxygenation product of arachidonic acid, in submicromolar concentrations elicited long-lasting contractions of the guinea-pig lung strip. The response to lipoxin A was not due to release of acetylcholine, histamine, noradrenaline or cyclo-oxygenase products. 15-hydroperoxyeicosatetraenoic acid (15-HPETE), one precursor of lipoxin A, also contracted the lung strip, but 15-HPETE was less potent on the guinea-pig trachea whereas 15-HPETE relaxed this preparation. Lipoxin A was also inactive on the guinea-pig ileum. Intravital microscopy of the hamster cheek pouch disclosed that lipoxin A, as well as 15-HPETE, induced arteriolar dilation but had no effects on microvascular permeability or leucocyte adherence to venular endothelium. Taken together, the leucocyte product lipoxin A displayed a pattern of activity in spasmogenic assays and on the microvasculature that was distinct from those known for prostaglandins, thromboxanes and leukotrienes. The findings indicate that lipoxin A is an additional arachidonic acid derived autacoid with biological actions on smooth muscle in vitro and in vivo.
D000818:Animals; D001095:Arachidonic Acids / Q000494:pharmacology; D001158:Arteries / Q000187:drug effects*; D001160:Arterioles / Q000187:drug effects*; D006224:Cricetinae; D006168:Guinea Pigs; D006801:Humans; D006893:Hydroxyeicosatetraenoic Acids / Q000494:pharmacology*; D015289:Leukotrienes; D008054:Lipid Peroxides / Q000494:pharmacology; D044045:Lipoxins; D008168:Lung / Q000187:drug effects*; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects*
D001095:Arachidonic Acids; D006893:Hydroxyeicosatetraenoic Acids; D015289:Leukotrienes; D008054:Lipid Peroxides; D044045:Lipoxins; C040527:lipoxin A4; C025086:15-hydroperoxy-5,8,11,13-eicosatetraenoic acid