Valutazione del ruolo dell’ossido d’azoto sulla fatica diaframmatica nel suino

In 12 anaesthetized and mechanically ventilated Large White pigs, divided into two grous, we analyzed the effect of nitric oxide (NO) on the diaphragmatic fatigue induced by phrenic nerve stimulation. The first group was treated with NG-nitro-L-arginine methyl ester (L-NAME, 5 mg/kg i.v.) to block endogenous NO synthesis. The second group was treated with sodium nitroprusside (SNP, 0.57 mg/kg i.v.) as NO donor. L-NAME decreased the diaphragmatic contraction during endurance test (stimulation for 30 sec at 10 Hz and 15 V)and increased mean systemic arterial pressure (PAM) and vascular resistance (RVS). SNP also caused an impairment of diaphragmatic function, but this was associated with a decrease in PAM and RVS. Also if we can not exclude a NO effect on diaphragmatic activity, probably the decreased resistance to fatigue after phrenic nerve stimulation by us observed, is due to the reduction of diaphragmatic blood flow.