Objective To investigate the effects of docosahexaenoic acid(DHA)on sodium channel current(INa)and transient outward potassium channel current(Ito)in rat ventricular myocytes and to evaluate potential anti-arrhythmic mechanisms of DHA.Methods INa and Ito of individual ventricular myocytes were recorded by patch-clamp technique in whole-cell configuration at room temperature.Effects of DHA at various concentrations(0,20,40,60,80,100 and 120 μmol/L)on INa and Ito were observed.Results (1) INa was blocked in a concentration-dependent manner by DHA,stably inactivated curves were shifted to the left,and recover time from inactivation was prolonged while stably activated curves were not affected by DHA.At-30 mV,INa was blocked to(1.51 ±1.32)%,(21.13±4.62)%,(51.61 ±5.73)%,(67.62 ±6.52)%,(73.49±7.59)%and(79.95±7.62)%in the presence of above DHA concentrations(all P<0.05,n=20),and half-effect concentration(EC50)of DHA on INa was(47.91±1.57)μmol/L(2) Ito were also blocked in a concentration-dependent manner by DHA,stably inactivated curves were shifted to the left,and recover time from inactivation was prolonged with increasing concentrations of DHA,and stably activated curves were not affected by DHA.At+70 mV,Ito was blocked to(2.61 ±0.26)%,(21.79±4.85)%,(63.11 ±6.57)%,(75.52 ±7.26)%,(81.82 ±7.63)%and(84.33±8.25)%,respectively,in the presence of above DHA concentrations(all P<0.05,n=20),and the EC50 of DHA on Ito was(49.11±2.68)μmol/1.Conclusion The blocking effects of DHA on APD and Ito may serve as one of the anti-arrhythmia mechanisms of DHA.

Objective To analyze the echocardiographic standardized myocardial segmentation features in patients with left ventricular noncompaction ( LVNC ). Methods Echocardiographic characteristics of 9 patients with LVNC were analyzed and the localization of lesions were determined according to the standardized myocardial segmentation (SMS) recommended by American Heart Association (AHA). Results Loose trabeculation in the myocardial lesions were evidenced in all LVNC patients. Communication between deep intertrabecular recess and LV cavity was evident with color flow imaging. According to SMS of AHA, noncompaction of ventricular myocardium was localized in apical segment in all 9 patients, in apical segment of the inferior wall (IW) in 9 patients, in apical segment of the lateral wall (LW) in 7 patients, in middle segment (MS) of IW in 7 patients, in MS of LW in 6 patients. One NC segment was also evidenced in apical segment and MS of septal ventricular wall, basal segment of IW and LW and right ventricular apex, respectively. NC was not found in left ventricular anterior wall. Conclusion Echocardiographic standardized myocardial segmentation is helpful to diagnose LVNC and NC was mostly localized in the apical segments of LVNC patients.

Objective To investigate the effects of docosahexaenoic acid (DHA) on large-conductance Ca2 + -activated K+ ( BKCa ) channels and voltage-dependent K+ ( Kv ) channels in rat coronary artery smooth muscle cells ( CASMCs ),and evaluate the vasorelaxation mechanisms of DHA.Methods BKCa and Kv currents in individual CASMC were recorded by patch-clamp technique in whole-cell configuration.Effects of DHA at various concentrations (0,10,20,40,60 and 80 μ mol/L) on BKCa and Kv channels were observed.Results ( 1 ) DHA enhanced IBKCa and BKCa tail currents in a concentration-dependent manner while did not affect the stably activated curves of IBKCa+ IBKCa current densities were (68.2±22.8),(72.4 ±24.5),(120.4 ±37.9),(237.5 ±53.2),(323.6 ±74.8) and (370.6 ±88.2 )pA/pF respectively (P ＜ 0.05,n =30) with the addition of 0,10,20,40,60 and 80 μmol/L DHA concentration,and half-effect concentration ( EC50 ) of DHA was (36.22 ± 2.17 ) μmol/L.(2) IKv and Kv tail currents were gradually reduced,stably activated curves of IKv were shift to the right,and stably inactivated curves were shifted to the left in the presence of DHA.IKv current densities were (43.9 ±2.3),(43.8±2.3),(42.9±2.0),(32.3±1.9),(11.7±1.5) and (9.6 ±1.2)pA/pF respectively(P＜0.05,n =30) post treatment with 0,10,20,40,60 and 80 μmol/L DHA under manding potential equal to +50 mV,and EC50 of DHA was (44.19 ±0.63) μmol/L.Conclusion DHA can activate BKCa channels and block Kv channels in rat CASMCs,the combined effects on BKCa and Kv channels lead to the vasodilation effects of DHA on vascular smooth muscle cells.