ABSTRACT
Objective To explore the mechanisms of ligament of Marshall (LOM) initiat and sustain atrial fibrillation (AF).Methods The electrophysiologic properties of canine LOM were investigated using multipolar catheter mapping(normal canines,n =4,group A;AF canines,n =5,group B).The programmed stimulation were performed in the LOM,PV-left atrium(LA)junction and LA,respectively.Activations maps of LOM were analyzed from episodes of spontaneous onset of AF and initiation of induced AF by a single extrastimulus.The effectives refractory period of each part was compared and statistically analyzed among three parts in each group and between the two groups.LOM were cutted with surgical incision technology.The inducing rate of AF and the mapping rate of double potential and fragmented electrocardiogram were compared and statistically analyzed pro and post isolation of LOM.Results The incidence of abnormal potential of LOM in the two groups was significantly different(P ＜0.01),re-entry cycle(group A 25％ vs.B group 80％),tachycardia(group A 25％ vs.B 100％),double potential(group A 25％ vs.group B 80％),fragmentation potential(group A 25％ vs.group 80％).There was a significant difference in the rate of LOM tachycardia induction before and after LOM intervention in group B (P ＜ 0.05,before 100％ vs.after 20％).Conclusion There are two possible mechanisms of LOM involved in the occurrence and maintenance of AF:one is that LOM induces AF through spontaneous excitation,the other is that LOM participates in the reentry of left atrium and pulmonary vein in the form of bypass to induce and maintain AF.
ABSTRACT
<p><b>OBJECTIVE</b>To explore the effects and related mechanisms of exogenous fibroblast growth factor (FGF) 21 on atherosclerosis in apolipoprotein E deficient (apoE-/-) mice.</p><p><b>METHODS</b>Male 17-week-old C57BL/6J mice and apoE-/- mice were randomly divided into three groups (n = 12 each): blank control group (C vehicle), atherosclerosis group without FGF21 (apoE-/- vehicle) and apoE-/- plus FGF21 (100 µg × kg⁻¹ × d⁻¹ subcutaneously treatment) . All mice were fed with high-fat diet for 4 weeks. After 4 weeks treatments, atherosclerotic lesions in aortic arch and inner diameter of abdominal aorta were measured by ultrasonography. Plasma lipid profiles, CRP and TNFα were measured. The whole aorta and aortic root were prepared for HE and oil red O staining to analyze lesion areas.</p><p><b>RESULTS</b>There was no evident plaque in C vehicle group. TC/HDL-C, LDL-C/HDL-C, non-HDL-C, expression of CRP and TNFα were significantly higher in apoE-/- vehicle group than in C vehicle group (all P < 0.05). IMT of aorta [(156.4 ± 17.6)µm vs. (57.8 ± 7.4)µm] were significantly higher in apoE-/- vehicle group than in C vehicle group (all P < 0.05). While FGF21 significantly reduced the lesion area in aorta arch [(1.42 ± 0.16) mm² vs. (2.30 ± 0.10) mm², P < 0.05] and the inner diameter of abdominal aorta [(0.97 ± 0.03) mm vs. (0.75 ± 0.18) mm, P < 0.05] compared to apoE-/- vehicle group. Similarly, TC/HDL-C(5.11 ± 0.70), LDL-C/HDL-C(3.90 ± 0.76), non-HDL-C[(6.33 ± 1.22)mmol/L], plasma CRP[(4.20 ± 1.03)mmol/L] and plasma TNFα[(1.29 ± 0.47)mmol/L] were also reduced by FGF21( all P < 0.05 vs. apoE-/- vehicle). Moreover, FGF21 decreased the IMT[(107.2 ± 33.5)µm vs. (156.4 ± 17.6)µm], lesion area of aorta [(14.26 ± 3.5)%] vs. [(23.06 ± 4.16)%] and plaque size of aorta root [(21.75 ± 7.14)% vs. (38.03 ± 5.76)%] (all P < 0.05 vs. apoE-/- vehicle).</p><p><b>CONCLUSIONS</b>FGF21 can protect apoE-/- mice from atherosclerosis by modifying lipid profiles and downregulating CRP and TNFα expressions.</p>