Effects of inhaled nitric oxide on airway resistance in guinea pigs

AIM: To observe the effect of continuous inhaled nitric oxide (NO) on airway resistance in guinea pigs. METHODS: 36 healthy male guinea pigs were divided into control group, isoproterenol group and two inhaled NO (20×10 -6 and 60×10 -6 ) groups. Respiratory resistance (R_E) and dynamic compliance(C_ dyn )were recorded before and after evoked by histamine at different doses. RESULTS: After injections of intravenous histamine at 80,120 and 160 μg/kg, the R_E of inhaled NO groups were apparently lower than that of control group. Compared with control group, the C_ dyn of inhaled NO groups were significantly higher after administration of histamine at 80, 120 and 160 μg/kg. After given histamine at more than 80 μg/kg,the R_E of inhaled NO groups were higher and the C_ dyn lower than those of isoproterenol group. CONCLUSION: Inhalation of 20×10 -6 NO and 60×10 -6 NO can inhibit the increase in airway resistance induced by higher doses (80,120 and 160 μg/kg )of intravenous histamine, but the effect of intravenous isoproterenol seems stronger.