Molecular mechanisms of early atrial remodeling by rapid atrial pacing in rabbits

摘要

Objective: To establish a rabbit atrial fibrillation model with rapid atrial pacing (RAP) and investigate its ultrastructural changes and expressions of L-type calcium channel subunits and potassium channel Kv4. 3. Methods: Thirty-six rabbits were performed electrical stimulation through bipolar endo-cardial led by surgical technique, 600 beat per min from 0 to 48 h. Atrial ultrastructure was observed by transmission electron microscope (TEM) after different pacing times. mRNA were measured by reverse transcription-polymerase chain reaction (RT-PCR). Results: Atrial ultrastructure had alteration after 3 hours' pacing, such as mitochondria vacuolization, myofilament lysis and glucogen aggregation. The mRNA of the Ca~(2+) channel β_1 and α_1 subunits began to decrease after pacing of 6 h, which were paralleled with the change of Kv4. 3 mRNA. But the auxiliary subunit α_2 were not affected. Conclusion: Ultrastructural changes and mRNA levels of L-type calcium channel subunits and potassium channel Kv4. 3 are decreased after RAP, with a mechanism of transcriptional down-regulation of underlying ion channels due to calcium overloading after RAP.