Time Course Of Rat Gastrocnemius HSP70 Expression Under Differential Recovery Environment Following Acute Normobaric Hypoxic Treadmill

1 PurposeTime course of rat gastrocnemius HSP70 expression and indexes of free radicals metabolism under normoxia,normobaric hypoxia(oxygen concentration is 12.7%) recovery environment following one single bout of acute normobaric hypoxic treadmill exercise.2 Materials and methodsAdult Male Sprague-Dawley rats were randomly divided into eight groups(n=6) according to the following independent variables:normoxia control(C);immediately after one single bout of acute normobaric hypoxic treadmill exercise(HE);1 day(N1),2 days(N2),7days(N7) recovery from normoxia;and 1 day(H1),2 days(H2),7days(H7) recovery from normobaric hypoxia.All rats were killed by pentobarbital sodium through intraperitoneal injection immediately after exercise,the gastrocnemius muscle were quickly removed.Gastrocnemius HSP70 gene and protein expression were detected by real-time fluorescent quantitative RT-PCR and western blot analysis respectively.Muscle free radicals MDA,GSH-PX,T-SOD,CAT,and T-AOC were detected by kits.3 Results3.1 Exercise and hypoxia induced a significant(P＜0.05) increase in HSP70 gene expression immediately after exercise.Under normoxia recovery conditions,at 1 day HSP70 gene expression was decreased significant (P＜0.05) compared with HE;at 2days and 7 days,HSP70 gene expression were elevated gradually.Under normobaric hypoxia recovery conditions, at 1 day and 2 days HSP70 gene expression were increased gradually;at 7 days,HSP70 gene expression was decreased significant(P＜0.05) compared with H2.3.2 HSP70 protein expression tendency were different from gene expression. Immediately after exercise,HSP70 protein expression were elevated. Under normoxia recovery conditions,at 1 day HSP70 protein expression was significant(P＜0.05) increased compared with C;at 2 days the HSP70 protein expression was decresed,and at 7 days the HSP70 protein expression was elevated again.Under normobaric hypoxia recovery conditions,at 1 day HSP70 protein expression was elevated;at 2 days and 7 days,the HSP70 protein expression were fall-off.3.3 All gastrocnemius muscle indexes of free radicals metabolism were decreased immediately after exercise.Under normoxia recovery conditions,at 1 day,2 days and 7 days MDA concentration were elevated gradually;at 1 day the T-SOD(P＜0.05),CAT (P＜0.05) activities were elevated at the same time;at 2 days,T-SOD and CAT activities were decreased,and T-AOC antioxidant capacity was elevated;at 7 days,T-SOD and CAT activities were increased again,and T-AOC was elevated gradually,GSH-PX activity was significant(P＜0.05) decreased at 7 days postexercise.Under normobaric hypoxic recovery conditions,at 1 day,MDA concentration (P＜0.05),T-SOD(P＜0.05),CAT(P＜0.05),T-AOC(P＜0.05) activities were significant increased;at 2 days and 7 days,MDA concentration,T-SOD and CAT activities were decreased;T-AOC antioxidant capacity was increased at 2 days and decreased at 7 days.GSH-PX activity had no change postexercise.4 Conclusions4.1 One single bout of acute treadmill exercise under normobaric hypoxic could induce HSP70 gene and protein expression.4.2 HSP70 gene and protein expression at high level recovery under normobaric hypoxic longer than recovery under normoxia conditions postexercise.4.3 Time course of HSP70 protein expression and variance of indexes of free radicals metabolism were similarly.