Nitric oxide modulation of transcellular biosynthesis of cys-leukotrienes in rabbit leukocyte-perfused heart.
1. We have studied the role of nitric oxide (NO) in the regulation of the transcellular biosynthesis of sulphidopeptide leukotrienes (cys-LT) generated upon neutrophil-vascular wall interactions and their functional consequences, in the spontaneously beating, cell-perfused, heart of the rabbit. 2. Hearts were perfused under recirculating conditions (50 ml) with 5 x 10(6) purified human neutrophils (PMNL), and challenged with 0.5 microM A-23187 for 30 min. Coronary perfusion pressure (CPP) and left-ventricular end-diastolic pressure (LVEDP) were monitored. Cys-LT formation was measured by reversed phase high performance liquid chromatography (h.p.l.c.) and u.v. spectral analysis. Myeloperoxidase (MPO) enzyme activity, assayed in aliquots of the recirculating buffer, was used as a marker of PMNL, adhesion to the coronary endothelium. 3. Basal CPP and LVEDP values averaged 45 +/- 1.4 mmHg and 5 +/- 0.1 mmHg, respectively; A-23187 triggered an increase in CPP (134 +/- 9 mmHg, at 30 min) which was significantly attenuated by pretreatment with L-arginine, 100 microM (90 +/- 3 mmHg, at 30 min). Pretreatment with NG-monomethyl-L-arginine, 10 microM (L-NMMA), induced a marked increase in CPP (290 +/- 40 mmHg, at 20 min) and in LVEDP (47 +/- 16 mmHg), so pronounced that it caused cardiac arrest in systole in 5 out of 6 hearts and these were prevented by L-arginine, 100 microM, (CPP 115 +/- 10 mmHg, LVEDP 6 +/- 1.1 mmHg, at 30 min). 4. The increase in CPP was accompanied by the release of cys-LT in the circulating buffer, which was reduced significantly by L-arginine. Pretreatment with L-NMMA, caused a marked rise in cys-LT concentrations which was prevented by L-arginine. 5. Neither L-arginine nor L-NMMA affected directly the A-23187-induced arachidonic acid (AA) metabolism in isolated PMNL alone. 6. Pretreatment with L-NMMA caused a prompt drop in myeloperoxidase (MPO), activity, suggesting rapid adhesion of PMNL to the coronary wall; this effect was significantly blunted by L-arginine. 7. This study suggests that NO provides cardioprotection in an organ model of transcellular metabolism of cys-LT by preventing PMNL adhesion to the coronary intima.
Buccellati
C
C
Center for Cardiopulmonary Pharmacology, Institute of Pharmacological Sciences, Milan, Italy.
Rossoni
G
G
Bonazzi
A
A
Berti
F
F
Maclouf
J
J
Folco
G
G
Sala
A
A
D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006321:Heart / Q000187:drug effects / Q000502:physiology*; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D015289:Leukotrienes / Q000096:biosynthesis*; D008297:Male; D017202:Myocardial Ischemia / Q000503:physiopathology; D009504:Neutrophils / Q000502:physiology*; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D010477:Perfusion; D011817:Rabbits; D019323:omega-N-Methylarginine / Q000494:pharmacology
D004791:Enzyme Inhibitors; D015289:Leukotrienes; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D000001:Calcimycin; D019001:Nitric Oxide Synthase