Istituto di Fisiologia Clinica     
Baragatti B., Brizzi F., Ackerley C., Barogi S., Ballau L. R., Coceani F. Cyclooxygenase-1 and cyclooxygenase-2 in the mouse ductus arteriosus: individual activity and functional coupling with nitric oxide synthase. In: British Journal of Pharmacology, vol. 139 (08) pp. 1505 - 1515. British Pharmalogical Society, 2003.
1. Prenatal patency of the ductus arteriosus is maintained by prostaglandin (PG) E2, conceivably in concert with nitric oxide (NO). Local PGE2 formation is sustained by cyclooxygenase-1 (COX1) and cyclooxygenase-2 (COX2), a possible exception being the mouse in which COX1, or both COXs, are reportedly absent. Here, we have examined the occurrence of functional COX isoforms in the near-term mouse ductus and the possibility of COX deletion causing NO upregulation. 2. COX1 and COX2 were detected in smooth muscle cells by immunogold electronmicroscopy, both being located primarily in the perinuclear region. Cytosolic and microsomal PGE synthases (cPGES and mPGES) were also found, but they occurred diffusely across the cytosol. COX1 and, far more frequently, COX2 were colocalised with mPGES, while neither COX appeared to be colocalized with cPGES. 3. The isolated ductus from wild-type and COX1-/- mice contracted promptly to indomethacin (2.8 muM). Conversely, the contraction of COX2-/- ductus to the same inhibitor started only after a delay and was slower. 4. NG-nitro-L-arginine methyl ester (L-NAME, 100 muM) weakly contracted the isolated wild-type ductus. Its effect, however, increased three- to four-fold after deleting either COX, hence equalling that of indomethacin. 5. In vivo, the ductus was patent in all mice foetuses, whether wild-type or COX-deleted. Likewise, no genotype-related difference was noted in its postnatal closure. 6. We conclude that the mouse ductus has a complete system for PGE2 synthesis comprising both COX1 and COX2. The two enzymes respond differently to indomethacin but, nevertheless, deletion of either one results in NO upregulation. PGE2 and NO can function synergistically in keeping the ductus patent.
URL: http://www.nature.com/bjp/journal/v139/n8/pdf/0705391a.pdf
Subject Ductus arteriosus
prostaglandin E synthase
nitric oxide synthase
nitric oxide

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