Effetti vascolari e respiratori della NG-Nitro-L-arginina metil estere (L-NAME), inibitore della NO sintasi

To evaluate if circulatory and respiratory effects due to Platelet Activating Factor (PAF) administration are modulated by releasing of endogenous nitric oxide (NO), in six anesthetized, paralyzed and mechanically ventilated Large White pigs L-NAME (10 mg/kg iv), an inhibitor of NO synthase, was used. PAF (50 ng/kg iv) in control conditions caused bronchoconstriction, evidenced by an increase in resistances and elastances of the respiratory system, pulmonary hypertension and a transient systemic hypotension. L-NAME, administered in control conditions, caused an increase in systemic and pulmonary arterial pressure and a modest increase in resistances and elastances of the respiratory system. After PAF, L-NAME caused strengthened bronchoconstriction and pulmonary hypertension, without modifying systemic hypotension. These results show that endogenous NO counterbalances respiratory and pulmonary vascular effects of PAF, while it is not involved in the systemic hypotension PAF-dependent.