| Objective To observe the effects of vasoactive agents on PaO2 in acute lung injury rats induced by hydrochloric acid instillation.Methods Twenty-eight male SD rats were anesthetized with pentobarbital. The trachea was intubated and lungs mechanically ventilated with 100% of oxygen. The tidal volume was set at 10ml/kg, respiratory rate at 60 bpm, and I:E ratio of 1:2. The common carotid artery and the right internal jugular vein were cannulated for monitoring arterial pressure, gas sampling and drug administration respectively. The rats were then randomly divided into four groups with 7 each. Normal saline 0.8 ml was given intravenously before hydrochloric acid instillation (Saline Group). Esmolol 100μg/100g and nitroglycerine 10μg/100g (total volume of 0.8ml) was used to substitute the normal saline in the EN group, and esmolol 100μg/100g and phenylephrine 25μg/100g (total volume of 0.8ml) in the EP group, and Isoproterenol 0.2μg/100g (total volume 0.8ml) in the Iso group. The hydrochloric acid (0.1N, 1ml/kg) was instilled into lungs via endotracheal tube 1 minute following intravenous injecting normal saline or vasoactive agents.Results There were no statistical difference about the basic heart rates, mean arterial pressures and PaO2 among the groups. When compared with the saline group, the HR and MAP decreased in group EN (p<0.01), and the HR decreased and MAP increased in the EP (p <0.01), and HR increased and MAP decreased (p<0.01) in the Iso group. PaO2 (Arterial Oxygen Pressures) in all groups decreased significantly (p<0.01) following the hydrochloric acid instillation. However, PaO2 in the Iso group decreased less, and PaO2 in the EP group decreased more when compared with saline group and EN group (p<0.01).Conclusion Our data suggests that Isoproterenol lessens the PaO2 deterioration and the simultaneous use of esmolol and phenylephrine exacerbates the PaO2 deterioration after the pulmonary hydrochloric acid instillation. |
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