Abstract:Objective Calcium plays an important role in the impairment of heart function and arrhythmia under the condition of chronic hypoxia.This study is aimed to investigate the expression of calmodulin (CaM) and calcicum/calmodulin dependent protein kinase II (CaMKII) that regulate the calcium activity in myocardial cells through an animal model of chronic hypoxia .
Methods The expression of mRNA and protein of CaM and CaMKIIγ/and CaMKIIδ in myocardial cells were measured by RT-PCR and Western Blot in normal rats and hypoxia rats one and three weeks after exposure.The cardiac cells from the control group and the 3-week hypoxia group were cultured.the intracellular calcium activity was detected using laser confocal equipment.The effect of CaMKII on the calcium activity was evaluated by the application of KN-62 (CaMKII specific inhibitor).
Results The expression of CaM and CaMKII mRNA increased in hypoxia rats compared with that in control(P <0.01).The CaM and CaMKIIδmRNA expression was different between 1 week and the 3 week hypoxia groups (P < 0.01).The laser confocal demonstrated that the amplitude of calcium wave in hypoxic cells was not diferent from that in control, but the duration of calcium wave in hypoxic cells was longer than that in control(P < 0.01).After KN-62 used,the amplitude of calcium wave decreased and the duration of calcium wave prolonged significantly.
Conclusions The contents of CaM and CaMKII in myocardial cells increased under condition of chronic hypoxia as a compensation to keep calcium homeostasis in a certain time.