Abstract: AIM: To study the effects of iptakalim, a novel ATP-sensitive potassium channel opner, against deacclimatization to high altitude. METHODS: This study was performed with a randomized, double-blind, placebo-controlled, parallel-group design. Fifty-six male soldiers were randomly divided into two groups: treatment group (39 men) and control group (17 men). The subjects were taken iptakalim tablets (5 mg/tablet, once a day) or placebo(once a day) respectively,for 7 months. The treatment was stopped at the 2 days before the subjects return to 3400 m altitude, and then returned to plain (1400 m). The questionnaire of symptoms of deacclimatization to high altitude was used on the 2nd, 4th, 6th day after the subjects returned to 1400 m altitude and the scores of deacclimatization symptoms were evaluated. RESULTS: Among the 17 men staying at 5200-5380 m high altitude for a long time, the incidences of deacclimatization to high altitude were 82.4%, 52.9% and 23.5% on the 2nd, 4th, 6th day after they returned to 1400 m altitude,respectively. After treated with iptakalim for 7 months, the incidences of deacclimatization were 43.6%, 30.8% and 38.5%,respectively. The scores of deacclimatization symptoms of placebo-control group on the 2nd and 4th,6th day after returning to 1400 m were 6.0±1.9, 4.6±1.0 and 3.8±1.5 respectively, while those in iptakalim-treated group were 4.4±2.4, 3.3±1.8 and 4.0±1.5 respectively. Compared with control, symptoms of deacclimatization to high altitude of treatment group were reduced significantly on the 2nd and 4th day after returning to 1400 m. There was no statistically significant difference in scores of deacclimatization symptoms between the two groups on the 6th day. CONCLUSION: Iptakalim can decrease the incidence of deacclimatization to high altitude, mitigate the symptoms of deacclimatization to high altitude. Iptakalim have a significant effect on prevention and treatment of deacclimatization to high altitude.

Key words: Deacclimatization to high altitude, ATP-sensitive potassium channel opner, Iptakalim