The properties of the inward-rectifying potassium current (IK1) were studied in the single myocytes isolated from adult mouse ventricles by the whole-cell patch-damp technique for the first time. Most of the propertie...The properties of the inward-rectifying potassium current (IK1) were studied in the single myocytes isolated from adult mouse ventricles by the whole-cell patch-damp technique for the first time. Most of the properties of IK1 including channel conductances, activation, inactivation, rectification and external K+ sensitivity in mouse ventricular myocyte were similar to those in other species, but the current-voltage (1-V) curve of mouse ventricular myocyte showed no negative slope, i.e the slope in the range of membrane potential 50 mV positive to the reversal potential (VRev) was virtually flat and remained at a low current level ((59±39) pA). Under the superfusion of Tyrode's solution with 3mmol/L K+ and 3mmol/L Cs+, IK1 in the above region nearly decreased to zero, and then the early after-depolarization (EAD) occurred. The results suggest that this distinctive characteristic of IK1 in mouse ventricular myocyte may relate to the high susceptibility to EA0 in mouse myocardium. The inhibition of IK1 seems to be a prerequisite for the occurrence of EAD in this experiment.展开更多
BACKGROUND Ventricular arrhythmia is a common type of arrhythmia observed in clinical practice.It is primarily characterized by premature ventricular contractions,ventricular tachycardia,and ventricular fibrillation.A...BACKGROUND Ventricular arrhythmia is a common type of arrhythmia observed in clinical practice.It is primarily characterized by premature ventricular contractions,ventricular tachycardia,and ventricular fibrillation.Abnormal formation or transmission of cardiac electrical impulses in patients affects cardiac ejection function.It may present with symptoms such as palpitations,dyspnea,chest discomfort,and reduced exercise tolerance.In severe cases,ventricular arrhy-thmia can even lead to death.Therefore,prompt treatment is very much essential upon diagnosis.The symptoms did not improve after previous conventional drugs and electrical defibrillation treatment,but the ventricular arrhythmia was prevented after the addition of nicorandil.CASE SUMMARY A 75-year-old female patient was admitted to the hospital because of intermittent chest tightness,shortness of breath for 10 days,and fainting once for 7 days.Combined with laboratory tests and auxiliary examination,the patient was tentatively diagnosed with coronary heart disease or arrhythmia-atrial fibrillation.After admission,the patient had intermittent ventricular arrhythmia,which was uncontrolled with lidocaine,defibrillation,and amiodarone.However,when she was treated with nicorandil,the ventricular arrhythmia stopped.Nicorandil mitigates the action potential duration by facilitating the opening of potassium ion channels,thereby regulating the likelihood of premature and delayed depolar-ization in two distinct phases and subsequently averting the onset of malignant ventricular arrhythmia.Nicorandil may inhibit ventricular arrhythmia by dilating coronary arteries,improving coronary microcirculation and reducing myocardial fibrosis.CONCLUSION option for inhibiting ventricular arrhythmias.展开更多
文摘The properties of the inward-rectifying potassium current (IK1) were studied in the single myocytes isolated from adult mouse ventricles by the whole-cell patch-damp technique for the first time. Most of the properties of IK1 including channel conductances, activation, inactivation, rectification and external K+ sensitivity in mouse ventricular myocyte were similar to those in other species, but the current-voltage (1-V) curve of mouse ventricular myocyte showed no negative slope, i.e the slope in the range of membrane potential 50 mV positive to the reversal potential (VRev) was virtually flat and remained at a low current level ((59±39) pA). Under the superfusion of Tyrode's solution with 3mmol/L K+ and 3mmol/L Cs+, IK1 in the above region nearly decreased to zero, and then the early after-depolarization (EAD) occurred. The results suggest that this distinctive characteristic of IK1 in mouse ventricular myocyte may relate to the high susceptibility to EA0 in mouse myocardium. The inhibition of IK1 seems to be a prerequisite for the occurrence of EAD in this experiment.
文摘BACKGROUND Ventricular arrhythmia is a common type of arrhythmia observed in clinical practice.It is primarily characterized by premature ventricular contractions,ventricular tachycardia,and ventricular fibrillation.Abnormal formation or transmission of cardiac electrical impulses in patients affects cardiac ejection function.It may present with symptoms such as palpitations,dyspnea,chest discomfort,and reduced exercise tolerance.In severe cases,ventricular arrhy-thmia can even lead to death.Therefore,prompt treatment is very much essential upon diagnosis.The symptoms did not improve after previous conventional drugs and electrical defibrillation treatment,but the ventricular arrhythmia was prevented after the addition of nicorandil.CASE SUMMARY A 75-year-old female patient was admitted to the hospital because of intermittent chest tightness,shortness of breath for 10 days,and fainting once for 7 days.Combined with laboratory tests and auxiliary examination,the patient was tentatively diagnosed with coronary heart disease or arrhythmia-atrial fibrillation.After admission,the patient had intermittent ventricular arrhythmia,which was uncontrolled with lidocaine,defibrillation,and amiodarone.However,when she was treated with nicorandil,the ventricular arrhythmia stopped.Nicorandil mitigates the action potential duration by facilitating the opening of potassium ion channels,thereby regulating the likelihood of premature and delayed depolar-ization in two distinct phases and subsequently averting the onset of malignant ventricular arrhythmia.Nicorandil may inhibit ventricular arrhythmia by dilating coronary arteries,improving coronary microcirculation and reducing myocardial fibrosis.CONCLUSION option for inhibiting ventricular arrhythmias.
