Effects of adiponectin on genioglossus contractile properties in chronic intermittent hypoxia rats

Objective To investigate the effects of adiponectin (Ad) on genioglossus contractile properties in rats with chronic intermittent hypoxia (CIH).Methods Thirty-nine healthy male Wistar rats were randomly divided into 3 groups,normal control (NC) group,CIH group and CIH+Ad group with 13 rats in each.Rats in NC group were kept breathing normal air,while rats in both CIH and CIH+Ad groups experienced the same CIH environment (CIH 8 h/d for successive 35 days).Rats in CIH+Ad group were given intravenous Ad supplement at the dosage of 10 μg twice a week for successive 5 weeks.Rats in the NC and CIH groups were injected with normal saline as a control.After CIH exposure,the levels of serum Ad and genioglossus contractile properties were compared among different groups.Results ①Serum Ad level was significantly lower in CIH group than that in NC group [(1 210.32±84.20) μg/L,(2 236.43±117.72) μg/L,P ＜0.01].Serum Ad level in CIH+Ad group [(1 843.80±91.11) μg/L]was significantly higher than that in CIH group but lower than that in NC group (all P ＜0.01).②Twitch tension,time to peak tension,half relaxation time and tetanic tension were significantly lower in CIH group than those in NC group (P ＜0.01).Those contractile properties were improved in CIH+ Ad group (P ＜0.05).③Tetanic fatigue indexes of three groups were decreased more rapidly in the first 20 seconds than those in the following 100 seconds.Tetanic fatigue indexes in NC and CIH+Ad groups were significantly higher than that in CIH group.Conclusions CIH could lead to hypoadiponectinemia,impaired genioglossus contractile properties and decreased fatigue resistence in rats.Such changes could be partially improved by supplement of adiponectin. Key words: Adiponectin;  Hypoxia ; Genioglossus;  Contraction