In pigs, inhaled nitric oxide (NO) counterbalances PAF-induced pulmonary hypertension.
In 6 anesthetized mechanically ventilated pigs we have studied the effects of inhalation of 80 ppm of nitric oxide (NO) before and after platelet-activating factor (PAF) administration (50 ng/kg iv). Our results show that NO inhalation causes a decrease in pulmonary arterial pressure and in heart rate without affecting other circulatory parameters. PAF administration causes a pulmonary hypertension and a prompt and brief decrease in systemic pressure. Inhalation of NO reduces the pulmonary hypertension, without completely reversing PAF-dependent vasoconstriction. PAF administration to pigs pretreated with indomethacin produces a lesser increase in pulmonary vascular pressure. In this case, NO inhalation can restore to baseline values. Pretreatment of 3 of the 6 pigs with NG-nitro-L-arginine-methyl-ester did not prevent the prompt and brief PAF-induced systemic hypotension. In conclusion, our results show that NO reduces basal pulmonary vascular tone, acts as a pulmonary vasodilator on PAF-preconstricted vessels and is not involved in the brief systemic hypotension consequent to PAF administration.
Albertini
M
M
Istituto di Fisiologia Veterinaria e Biochimica, Università di Milano, Italia.
Clement
M G
MG
D000280:Administration, Inhalation; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects*; D005260:Female; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000008:administration & dosage / Q000494:pharmacology*; D010972:Platelet Activating Factor / Q000494:pharmacology*; D011651:Pulmonary Artery / Q000502:physiology*; D013552:Swine; D014661:Vasoconstriction / Q000187:drug effects
D010972:Platelet Activating Factor; D009569:Nitric Oxide; D001120:Arginine; D019331:NG-Nitroarginine Methyl Ester; D007213:Indomethacin