Influence of up-regulated expression of HSP70 on myocardial KCa3.1 in rabbits with atrial fibrillation caused by rapid atrial pacing / 心血管康复医学杂志

ABSTRACT

Objective:To observe influence of up‐regulated expression of myocardial heat shock protein (HSP) 70 in‐duced by heat stress on myocardial calcium‐activated potassium channel (KCa ) 3.1 expression in rabbits with atrial fibrillation (AF) caused by rapid atrial pacing (RAP) .Methods :A total of 24 New Zealand white rabbits were ran‐domly divided into sham operation group (n=8 ,only implant electrode without pacing ) ,pacing group (n=8 ,right atrium (RA) received RAP at 600 times/min for 6h) and heat stress pacing group (heat stress group ,n=8 ,received heat stress preconditioning ,then the same RAP as pacing group ) .Results:Compared with sham operation group and pacing group ,there were significant up‐regulation of HSP70 mRNA and protein expression in different sites of heart [HSP70 protein ,left atrium (LA):(39.00 ± 3.21) vs .(39.75 ± 2.82) vs .(69.75 ± 3.45) ,RA: (38.38 ± 2.92) vs .(39.50 ± 3.89) vs .(69.00 ± 2.93) ,left atrial appendage (LAA):(37.75 ± 3.28) vs .(39.00 ± 3.89) vs . (68.63 ± 3.23) ,right atrial appendage (RAA): (37.00 ± 3.85) vs .(38.38 ± 3.74) vs .(68.75 ± 2.82)] in heat stress group , P0.05 ;compared with pacing group with down‐regulation of KCa3.1 mRNA and protein expressions ,there were significant up‐regulation of KCa3.1 mRNA and protein expressions in different sites of heart [KCa3.1 protein ,LA:(21.25 ± 1.67) vs .(24.00 ± 2.62) ,RA :(21.13 ± 1.96) vs .(23.75 ± 1.83) ,LAA :(21.00 ± 2.07) vs .(23.75 ± 1.67) ,RAA:(20.88 ± 2.03) vs .(23.50 ± 2.45)] in heat stress group ,P0. 05. Conclusion:Heat stress may induce up‐regulated expression of myocardial HSP 70 of myocardium ,and HSP 70 may inhibit down‐regulation of KCa 3. 1 mR‐NA and protein expressions in rabbits with atrial fibrillation.