SELECTIVE PULMONARY VASODILATION BY INTRAVENOUS-INFUSION OF AN ULTRASHORT HALF-LIFE NUCLEOPHILE NITRIC-OXIDE ADDUCT

Background: PROLI/NO (C5H7/N3O4Na2 . CH3OH) is an ultrashort-acting nu cleophile/NO adduct that generates NO (half-life 2 s at 37 degrees C a nd pH 7.4). Because of its short half-life, the authors hypothesized t hat intravenons administration of this compound would selectively dila te the pulmonary vasculature but cause little or no systemic hypotensi on, Methods; in eight awake healthy sheep with pulmonary Hypertension induced by 9,11-dideoxy-9 alpha,11 alpha-methanoepoxy prostaglandin F- 2 alpha, the authors compared PROLI/NO with two reference drugs-inhale d NO, a well-studied selective pulmonary vasodilator, and intravenous sodium nitroprusside (SNP), a nonselective vasodilator. Sheep inhaled 10, 20, 40, and 80 parts per million NO or received intravenous infusi ons of 0.25, 0.5, 1, 2, and 4 mu g.kg(-1).min(-1) of SNP or 0.75, 1.5, 3, 6, and 12 mu g.kg(-1).min(-1) of PROLI/NB. The order of administra tion of the vasoactive drugs (NO, SNP, PROLI/NO) and their doses were randomized. Results: Inhaled NO selectively dilated the pulmonary vasc ulature. Intravenous SNP induced nonselective vasodilation of the syst emic and pulmonary circulation. Intravenous PROLI/NO selectively vasod ilated the pulmonary circulation at doses up to 6 mu g.kg(-1).min(-1), which decreased pulmonary vascular resistance by 63% (P < 0.01) from pulmonary hypertensive baseline values without changing systemic vascu lar resistance. At 12 mu g.kg(-1).min(-1), PROLI/NO decreased systemic and pulmonary vascular resistance and pressure. Exhaled NO concentrat ions were higher during PROLI/NO infusion than during SNP infusion (P < 0.01 with all data pooled), Conclusions: The results suggest that PR OLI/NO could be a useful intravenous drug to vasodilate the pulmonary circulation selectively.