Hyperpolarization activated cation current (If) in cardiac myocytes from pulmonary vein sleeves in the canine with atrial fibrillation

Objective To investigate the characteristics of ectopic automaticity and cation current (If) of cardiac myocytes from pulmonary vein sleeves (PVs) in canines with atrial fibrillation. Methods The canines (8–10 years old) were subjected to long-term, rapid atrial pacing (RAP) for 10 weeks, which induced the atrial fibrillation model. Disassociation of PVs of canines yielded single cardiac myocytes from a Landengorff column. Action potential, If and hyperpolarisation activated cyclic nucleotide-gated (HCN) currents were measured with the patch-clamp technique. Results Compared with the control group, cardiac myocytes from the RAP canine PVs had spontaneous diastolic depolarization, shorter action potential duration, and larger If densities. In the group of RAP cells, the half maximal activation potential (V1/2) was found to be less negative (��105.5 ±5.2 mV) compared to control cells (��87.3 ±4.9 mV). Current densities of If were increased significantly by β-adrenergic receptor stimulation with isoproterenol and caused an acceleration of current activation. In contrast, If currents in the RAP were reduced by carvedilol, a selective beta-adrenergic receptor. Another important finding is that HCN4-based channels may make a significant contribution to If in PVs cells, but not HCN2. Meanwhile, HCN4 current significantly increases in canine PVs cardiac myocytes with RAP. Conclusions The spontaneous action potential and larger If currentwere observed in the PVs cardiac myocytes using RAP, whichmay contribute tomore ectopic activity events to trigger and maintain atrial fibrillation.

A survey of impulse control disorders in Parkinson’s disease patients in Shanghai area and literature review

Background:Levodopa and dopamine agonists are the main treatments for Parkinson’s disease(PD)in recent years.Increased drug dosages are linked to some severe side effects,one of which is impulse control disorders(ICD).Many studies have reported the related risk factors of ICDs,such as dopamine agonist,male sex,younger age,earlier age of onset and so on.This study aims to investigate the incidence of ICD in Chinese PD patients from Shanghai area,explore the association of ICD with dopamine replacement therapy(DRT).Methods:Two hundred seventeen PD patients were consecutively recruited from the Movement Disorder Clinic of Ruijin Hospital from March to October 2013.Minnesota Impulsive Disorders Interview was used to assess the PD patients.PD patients with possible ICD would undergo a further interview by a movement disorder specialist to confirm the diagnosis.Clinical information was also collected.Results:Nine PD patients(4.15%)showed ICD behaviors as follows:hypersexuality(4,1.84%),pathological gambling(3,1.38%),binge eating(1,0.46%),compulsive shopping(1,0.46%).Compared with the non-ICD PD group,ICD PD group took more dopamine agonists(LED 119.4±86.4 mg/d vs 60.5±80.5 mg/d,P=0.019),had higher total levodopa equivalent dosage(TLED 912.81±878.73 mg/d vs 503.78±359.14 mg/d,P=0.031),and had higher H&Y stage(2.33±0.87 vs 1.41±0.52,p=0.013).However,logistic regression analysis didn’t reveal the above factors as independent risk factors of ICD behaviors in our study.Conclusion:The incidence of ICDs behaviors in PD patients in our study is much lower than in western countries.ICD-PD group took higher dopamine agonists and higher total levodopa equivalent dosage,even though logistic regression analysis didn’t reveal them as independent risk factors.