RESUMO
Autonomic nervous system activation can result in significant changes of atrial electrophysiology and facilitate induction of atrial fibrillation. By recording influence of different concentrations of acetylcholine (ACh) on atrial fibers (AF), we investigated the role of the increased vagal tone in electrical remodeling in atrial fibrillation. Parameters of action potentials and force contraction (Fc) in atrial fibers were recorded by using standard intracellular microelectrode technique and force transducer. It was found that: (1) ACh at 0.1 µmol/L had no significant influence on spontaneous action potentials (SAPs) and Fc (n=6, P>0.05); ACh at both 1.0 and 10.0 µmol/L shortened action potential duration (APD) and Fc of human AF from right atrium (n=6, P<0.05); there was no significant difference in shortening APD between 10.0 and 1.0 µmol/L of ACh; (2) ACh at 0.1 µmol/L had no significant desensitization (n=6, P>0.05), but ACh at 1.0 and 10.0 µmol/L had desensitization (n=6, P<0.05) to SAPs and Fc. The desensitization of ACh on APD in AF was concentration- and time-dependent. It was shown that APD was longer than the control along with extending time of continuous Tyrode's solution perfusion after desensitization. It is concluded that ACh changes the electrophysiological characteristics of human AF, indicating that increased vagal tone plays a role in the development of a vulnerable substrate for atrial electrical remodeling in atrial fibrillation.
Assuntos
Acetilcolina/farmacologia , Potenciais de Ação/efeitos dos fármacos , Fibrilação Atrial/fisiopatologia , Função Atrial/fisiologia , Potenciais de Ação/fisiologia , Função Atrial/efeitos dos fármacos , Átrios do Coração/inervação , Humanos , Técnicas In VitroRESUMO
Autonomic nervous system activation can result in significant changes of atrial electrophysiology and facilitate induction of atrial fibrillation.By recording influence of different concentrations of acetylcholine (ACh) on atrial fibers (AF),we investigated the role of the increased vagal tone in electrical remodeling in atrial fibrillation.Parameters of action potentials and force contraction (Fc) in atrial fibers were recorded by using standard intracellular microelectrode technique and force transducer.It was found that:(1) ACh at 0.1 μmol/L had no significant influence on spontaneous action potentials (SAPs) and Fc (n=6,P>0.05); ACh at both 1.0 and 10.0 μmol/L shortened action potential duration (APD) and Fc of human AF from right atrium (n=6,P<0.05); there was no significant difference in shortening APD between 10.0 and 1.0 μmol/L of ACh; (2) ACh at 0.1 μmol/L had no significant desensitization (n=6,P>0.05),but ACh at 1.0 and 10.0 μmol/L had desensitization (n=6,P<0.05) to SAPs and Fc.The desensitization of ACh on APD in AF was concentration- and time-dependent.It was shown that APD was longer than the control along with extending time of continuous Tyrode's solution perfusion after desensitization.It is concluded that ACh changes the electrophysiological characteristics of human AF,indicating that increased vagal tone plays a role in the development of a vulnerable substrate for atrial electrical remodeling in atrial fibrillation.