[Effect of N-acetyl-L-cysteine on vascular heterogeneity of microcirculation in endotoxemia rabbits and its mechanism].

Objective To study the effect of N-acetyl-L-cysteine (NAC) on vascular heterogeneity in microcirculation dysfunction caused by endotoxemia and its mechanism. Methods Eighteen Japanese big ear rabbits were divided into three groups: Control group, Lipopolysaccharides (LPS) group and LPS+ NAC group.A dose of 2 mg/kg LPS was injected to set up endotoxemia rabbit models.Rabbits in the LPS+ NAC group were infused with NAC at a dose of 350 mg/kg, and the same amount of normal saline were infected intravenously to the rabbits in the Control and LPS group.Macrocirculation parameters (central venous pressure, mean arterial pressure and cardiac output) and microcirculation parameters (microvascular flow index and flow heterogeneity index) in all the groups were recorded at 0 and 2 h. Artery and vein S-nitrosohemoglobin were detected at 2 h. Variables were compared by one-way analysis of variance.Dunnett-t3 was used for comparisons between two groups. Results Microvascular flow index in Control group and LPS+ NAC group at 2 h were much higher than that in LPS group (2.82±0.09 vs 1.11±0.16, P<0.001; 1.60±0.17 vs 1.11±0.16, P<0.001), and flow heterogeneity index in Control group and LPS+ NAC group at 2 h were significantly lower than that in LPS group (0.16±0.06 vs 1.16±0.33, P<0.001; 0.80±0.12 vs 1.16±0.33, P=0.035). The arterial-venous difference of S-nitrosohemoglobin content in Control group and LPS+ NAC group were higher than LPS group [(41±6) vs (27±5) nmol/L, P=0.002; (36±5) vs (27±5) nmol/L, P=0.010]. Conclusions In endotoxemia rabbits, NAC can improve the microcirculation dysfunction, especially vascular heterogeneity. It indicated that NAC could improve the ability of S-nitrosohemoglobin-mediated nitric oxide release from red blood cells. Key words: Endotoxemia; N-acetyl-L-cysteine; Microcirculation; Vascular heterogeneity