RESUMO
This study sought to explore the relationship between the change in ventricular electrical remodeling caused by mechano-electrical feedback and the expression of L-type Ca2+ -channel and/or sarcoplasmic reticulum Ca2+ -ATPase in the rabbits with congestive heart failure (CHF). 138 rabbits were divided into two groups (CHF and control). We measured the ventricular monophasic action potential duration (MAPD) and ventricular effective refractory period (VERP) during ventricular pacing at the stimulus frequency of 220/240/260 bpm in these rabbits. Rapid atrial pacing (260/min) was given for 30 minutes. The MAPD and VERP were measured again. Then ventricular fibrillation was induced by S1S2S3 program stimulation. We extracted the total RNA from the myocardium respectively and detected L-type Ca2+ -channel mRNA and sarcoplasmic reticulum Ca2+ -ATPase mRNA by use of Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR). In group CHF, with the increasing of preload/afterload, L-type Ca2+ -channel mRNA was up regulated after rapid atrial pacing when compared with that in control groups (P < 0.05). There was no significant change in sarcoplasmic reticulum Ca2+ -ATPase mRNA after rapid atrial pacing when compared with controls (P > or = 0.05). The changes in MAPD90 and VERP were related with the extent of L-type Ca2+ -channel mRNA up regulation. But the changes in MAPD90 and VERP were not significantly related with the extent of sarcoplasmic reticulum Ca2+ -ATPase mRNA up regulation. These findings suggest that Mechano-Electrical Feedback could increase the regional changes of ventricular electrical remodeling in rabbits with CHF and so to predispose them to ventricular arrhythmia. The changes may be related with the up regulation of L-type Ca2+ -channel mRNA, but not with sarcoplasmic reticulum Ca2+ -ATPase mRNA.