PT  - JOURNAL ARTICLE
AU  - Asma Yaghi
AU  - Christopher D. Webb
AU  - Jeremy A. Scott
AU  - Sanjay Mehta
AU  - John R. Bend
AU  - David G. McCormack
TI  - Cytochrome P450 Metabolites of Arachidonic Acid but Not Cyclooxygenase-2 Metabolites Contribute to the Pulmonary Vascular Hyporeactivity in Rats with Acute <em>Pseudomonas</em> Pneumonia
DP  - 2001 May 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 479--488
VI  - 297
IP  - 2
4099  - http://jpet.aspetjournals.org/content/297/2/479.short
4100  - http://jpet.aspetjournals.org/content/297/2/479.full
SO  - J Pharmacol Exp Ther2001 May 01; 297
AB  - We have previously demonstrated depressed vascular contractility in intralobar pulmonary artery (PA) rings isolated from rats with acutePseudomonas pneumonia. Here we describe the role of arachidonic acid (AA) metabolites in the regulation of pulmonary vascular tone in inflammation. Pneumonia was induced by intratracheal injection of P. aeruginosa organisms. Rats were sacrificed 44 h later. EETs and 20-HETE were formed at significantly lower rates in pneumonia compared with control lung microsomes. Vasoactive effects of CYP metabolites (5,6-EET, 8,9-EET, 11,12-EET, 14,15-EET, and 20-HETE) on small PA rings from control or pneumonia rats were assessed in vitro. All four EETs and 20-HETE were more potent PA vasoconstrictors than KCl or phenylephrine (PE). However, this potency was attenuated in PA rings from pneumonia lungs compared with control. In contrast, pneumonia had no effect on COX activity [total pulmonary prostaglandin (PG), PGE2, and 6-keto-PGF1α]. In vitro vascular contractility to KCl, PE, or PGF2α was assessed in small PA rings from control and pneumonia rats in the presence and absence of the COX-2 inhibitor NS-398 (10 μM). NS-398 did not reverse the attenuated contractile responses to KCl, PE, or PGF2α in pneumonia rats. Nitrite/nitrate levels, inducible nitric-oxide synthase and heme oxygenase activities were all significantly elevated in pneumonia lungs. In conclusion, vasodilator PGs produced by COX-2 do not contribute to the depressed PA contractility in this model of pneumonia. Depressed pulmonary production and vasoconstrictor effects of CYP metabolites of AA (possibly due to increased NO and/or carbon monoxide) indicate a potential role for these vasoactive metabolites in this model of acute pneumonia. The American Society for Pharmacology and Experimental Therapeutics