Effects of rapid atrial pacing on L-type calcium channel subunits and potassium channel Kv4.3 expressions in rabbits / 中华心血管病杂志

ABSTRACT

<p><b>OBJECTIVE</b>To investigate rapid atrial pacing (RAP) induced atrial ultrastructural changes and mRNA and protein expression changes of L-type calcium channel subunits and potassium channel Kv4.3 in a rabbit model.</p><p><b>METHODS</b>Thirty-six rabbits were electrically paced at a frequency of 600 beats/min for durations ranging from 0 - 48 h via bipolar endocardial leads through surgical techniques. Ultrastructural changes of the atrium were observed through a transmission electron microscope (TEM), L-type calcium channel subunits and potassium channel Kv4.3 expressions at mRNA and protein levels were analyzed by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot.</p><p><b>RESULTS</b>Atrial ultrastructure changes characterized by mitochondrial vacuolization, myofilament lysis, and glycogen accumulation were detected obvious at 3 h post pacing. Down-regulated mRNA expression of Ca(2+) channel beta1 and alpha1 subunits was observed 6 h post pacing, Kv4.3 mRNA down-regulation occurred 24 h post pacing, auxiliary subunit alpha2 was not affected by pacing. Protein expression of alpha1c subunit and potassium channel Kv4.3 paralleled their mRNA expression changes.</p><p><b>CONCLUSION</b>RAP induced ultrastructural changes of the atrium and down-regulated mRNA and protein expressions of L-type calcium channel subunits and potassium channel Kv4.3 occurred thereafter in response to intracellular calcium overload induced by RAP.</p>