Objectives To evaluate the changes in atrial effective refractory period （AERP） proprieties and in ionic currents in PVs myocytes from dogs subjected to rapid atrial pacing in PVs and right atrial appendage （RAA） ...Objectives To evaluate the changes in atrial effective refractory period （AERP） proprieties and in ionic currents in PVs myocytes from dogs subjected to rapid atrial pacing in PVs and right atrial appendage （RAA） and to relate these changes to the ability to induce AF. Methods Twelve mongrel dogs in normal sinus rhythm were paced from the superior left PVs or RAA at 500 bpm for 4 hours. Electrophysiologic studies conducted to determine changes in AERP, dispersion and rhythm. Ionic currents were studies with the patch clamp technique in single PVs myocytes in sham operated dogs and compared with those from PVs pacing and RAA pacing groups. Results The presence of rapid atrial pacing was associated with a marked shortening in AERP in both PVs and RAA pacing group with a marked increase of AERP dispersion in PVs pacing. Both L-type calcium current （Ica L ） and the transient outward current （ Ito ） were reduced in both groups with an increased significance in PVs pacing group. The density of ICa-L was decreased significantly from （ - 6. 03 ± 0. 63 ） pA./pF in the control group to （ -3.21 ±0. 34） pA/pF in PVs pacing group and （ - 4. 75 ± 0. 41 ） pA./pF in RAA pacing group （ n = 6, P 〈 0. 05 ） while the density of Ito was decreased significantly from （8.45 ± 0. 71 ） pA./pF in the control group to （ 5.21 ± 0. 763 ） pA./pF in PVs pacing group and （6. 84 ±0. 69 ） pA./pF in RAA pacing group （ n = 6, P 〈 0. 05 ）. Conclusions Our findings provide likely ionic mechanisms of shortened repolarization in induced atrial tachycardia with a decrease in Ica L and /tocurrent densities which is the likely mechanism for a decrease in Action potential duration （APD） rate adaptation in the canine rapid pacing model more pronounced in PVs pacing group underlying the crucial role of PVs in initiating AF.展开更多
目的探讨阻断自主神经系统对经肺静脉快速起搏造成的急性电重构的影响。方法成年杂种犬22只,随机分为对照组、阿托品组、美托洛尔组和阿+美组。首先测量起搏周长(PCL)分别为350 m s、400 m s时心房有效不应期(AERP),以能够1∶1起搏肺静...目的探讨阻断自主神经系统对经肺静脉快速起搏造成的急性电重构的影响。方法成年杂种犬22只,随机分为对照组、阿托品组、美托洛尔组和阿+美组。首先测量起搏周长(PCL)分别为350 m s、400 m s时心房有效不应期(AERP),以能够1∶1起搏肺静脉的最快频率刺激肺静脉10 m in,在刺激中止后即刻、5、10、15、20 m in时重复测量AERP。比较各组在起搏前后AERP和AERP频率适应性的变化。结果短阵快速肺静脉刺激可引起AERP明显缩短,AERP频率适应性下降,阻断迷走神经后明显减小电重构的程度。展开更多
文摘Objectives To evaluate the changes in atrial effective refractory period （AERP） proprieties and in ionic currents in PVs myocytes from dogs subjected to rapid atrial pacing in PVs and right atrial appendage （RAA） and to relate these changes to the ability to induce AF. Methods Twelve mongrel dogs in normal sinus rhythm were paced from the superior left PVs or RAA at 500 bpm for 4 hours. Electrophysiologic studies conducted to determine changes in AERP, dispersion and rhythm. Ionic currents were studies with the patch clamp technique in single PVs myocytes in sham operated dogs and compared with those from PVs pacing and RAA pacing groups. Results The presence of rapid atrial pacing was associated with a marked shortening in AERP in both PVs and RAA pacing group with a marked increase of AERP dispersion in PVs pacing. Both L-type calcium current （Ica L ） and the transient outward current （ Ito ） were reduced in both groups with an increased significance in PVs pacing group. The density of ICa-L was decreased significantly from （ - 6. 03 ± 0. 63 ） pA./pF in the control group to （ -3.21 ±0. 34） pA/pF in PVs pacing group and （ - 4. 75 ± 0. 41 ） pA./pF in RAA pacing group （ n = 6, P 〈 0. 05 ） while the density of Ito was decreased significantly from （8.45 ± 0. 71 ） pA./pF in the control group to （ 5.21 ± 0. 763 ） pA./pF in PVs pacing group and （6. 84 ±0. 69 ） pA./pF in RAA pacing group （ n = 6, P 〈 0. 05 ）. Conclusions Our findings provide likely ionic mechanisms of shortened repolarization in induced atrial tachycardia with a decrease in Ica L and /tocurrent densities which is the likely mechanism for a decrease in Action potential duration （APD） rate adaptation in the canine rapid pacing model more pronounced in PVs pacing group underlying the crucial role of PVs in initiating AF.
文摘目的探讨阻断自主神经系统对经肺静脉快速起搏造成的急性电重构的影响。方法成年杂种犬22只,随机分为对照组、阿托品组、美托洛尔组和阿+美组。首先测量起搏周长(PCL)分别为350 m s、400 m s时心房有效不应期(AERP),以能够1∶1起搏肺静脉的最快频率刺激肺静脉10 m in,在刺激中止后即刻、5、10、15、20 m in时重复测量AERP。比较各组在起搏前后AERP和AERP频率适应性的变化。结果短阵快速肺静脉刺激可引起AERP明显缩短,AERP频率适应性下降,阻断迷走神经后明显减小电重构的程度。
