DUAL ATRIOVENTRICULAR NODAL PATHWAYS ASSOCIATED WITH A NODOVENTRICULAR TRACT INSERTING INTO THE LEFT VENTRICLE A CASE REPORT

A patient with recurrent paroxysmal tachycardia of right bundle branch block morphology (RBBBM) and atrioventricular (AV) dissociation is demonstrat ed by electrophysiologic study to have dual AV nodaJ pathways and a unique left sided nodoventricular (NV) tract. Dual AV nodal pathway was manifest in three ways: sudden increment in AV nodal con duction in response to premature stimulation, dou ble ventricular responses to single atrial extrastimuli and alternating fast and slow pathway conduction during right atrial (RA) programmed stimulation or RA overdrive pacing. The A-H interval of the fast pathway was 180 msec and that of the s!ow pathway was 290-330 msec. During RA stimulation, conduc. tion over the slow pathway was associated with marked prolongation of AV conduction, decrease of the H-V interval (0-30 msec) and induction of a QRS morphology similar or identical to that recorded dur ing spontaneous tachycardia. Tachycardia could be initiated by RA stimulation when impulses were conducted over the slow pathway or by right ventri cuk:r stimulation. The variation of QRS duration from 90-125 msec in RBBBM tachycardia indicated that the reentry circuit was confined to the AV node using the slow pathway as the antegrade limb and the fast pathway as the retrograde Iimb and that the anomalous tract was a NV fiber rather than a fascicaloventricular fiber.     

Radiofrequency ablation: a cure for tachyarrhythmias

Radiofrequency (RF) ablation is a new modality of pennanently curing patients with various tachycardias using radiofrequency energy, a technique evolved in the past decade. RF ablation was performed on 913 patients with different tachyarrhythmias from April, 1994 to July, 1999. There were 491 men and 422 females aged 42 +/- 34 years (range 1 to 76 years). Supraventricular tachycardia (SVT) was present in 462 patients, accessory pathway mediated atrioventricular re-entrant tachycardia (AVRT) in 355 patients (377 accessory pathways) and idiopathic ventricular tachycardia (VT) in 96 patients. Amongst the patients with SVT, 402 had atrioventricular nodal re-entrant tachycardia (AVNRT), 22 had atrial flutter, 20 had ectopic atrial tachycardia and 18 had atrial fibrillation. RF successfully abolished the tachycardia in 400/402 patients (99.5%) with AVNRT, 330/377 (87.5%) accessory pathways in patients with AVRT, 14/22 patients (63.6%) of atrial flutter, 18/20 patients (90%) of atrial tachycardia and 79/96 patients (82.3%) with idiopathicVT. Successful AV nodal ablation with pacemaker implantation was done in 10/18 patients with chronic atrial fibrillation with fast ventricular rate and tachycardia induced cardiomyopathy. AV nodal modulation for atrial fibrillation was tried in the remaining 8 patients and was successful in 4 (4/8). The overall success rate for all arrhythmias was 93.6%, and there was no mortality. At a follow-up of 6.8 +/- 5.4 months, there was a recurrence in 34/420 patients (8%), in whom successful re-ablation was performed. One patient with AVNRT and another with a parahisian pathway developed complete heart block and were given pacemakers. One patient developed inferior wall infarction on the next day post RF. There were 4 patients who had pericardial tamponade necessitating pericardiocentesis and 2 patients developed deep vein thrombosis, which was treated conservatively. Thus RF ablation is an effective, safe and curative therapy for various arrhythmias.     

Efficacy and Mechanism of Intravenous Sotalol for Termination of Paroxysmal Supraventricular Tachycardia

ＳＶＴ ,ｉｎｃｌｕｄｉｎｇＡＶＲＴａｎｄＡＶＮＲＴ ,ｉｓａｋｉｎｄｏｆａｒｒｈｙｔｈｍｉａｏｆｔｅｎｓｅｅｎｉｎｃｌｉｎｉｃａｌｐｒａｃ ｔｉｃｅ .Ｓｏｔａｌｏｌ,ａｃｌａｓｓⅢａｎｔｉ ａｒｒｈｙｔｈｍｉｃｄｒｕｇｗｉｔｈａｄｄｉｔｉｏｎａｌβ ｂｌｏｃｋｉｎｇａｇｅｎｔｐｒｏｐｅｒｔｉｅｓ ,ｈａｓｂｅｅｎｗｉｄｅｌｙｕｓｅｄｔｏｔｒｅａｔｖａｒｉｏｕｓａｒｒｈｙｔｈｍｉａ(ｓｕｐｒａ ｖｅｎｔｒｉｃｕｌａｒａｎｄｖｅｎｔｒｉｃｕｌａｒ)ｅｆｆｉｃｉｅｎｔｌｙｉｎｗｅｓｔｅｒｎｃｏｕｎｔｒｉｅｓ[1 9]…     

Efficacy and Mechanism of Intravenous Sotalol for Termination of Paroxysmal Supraventricular Tachycardia

Objectives To study the efficacy and mechanism of intravenous sotalol(Sol) for termination of paroxysmal supra-ventricular tachycardia ( SVT). Methods Sol or normal saline (NS) were administrated intravenously in patients with SVT induced by trans-esophagus left atrial stimulation. Results Conversion to sinus rhythm occurred in 65.2% (15/23) patients who received Sol (Sol group) at total dose of 1.5 mg/kg, the average conversion time being ( 10. 7 ± 11.6) min after the start of sotalol infusion. Conversion to sinus rhythm appeared in 4.8% (1/21) patients who were treated with NS (NS group). The efficacy between two groups was significantly different ( P ＜0. 01 ). The site of termination of tachycardia was predominantly at the antegrade atrioventricular node ( AV N ) in atrioventricular reentrant tachycardia ( AV RT ) (3/4) and at the retrograde fast pathway of AV N in atrioventricular nodal reentrant tachycardia ( AV N RT ) ( 4 / 6 ) . During the course of Sol infusion, both ventricular rate of SVT and systolic blood pressure ( SBP ) decreased. HR decreased from (173. 3±28. 4) min-1(before So l administration) to (159. 6-±-23. 8) and (152. 0±22. 2)min-1(3,5 minutes after the start of Sol infusion respectively, P ＜ 0. 01) and SBP from (16.31-±-2.27) kPa to (14.82±2. 61) and (14. 61-±-2. 60) kPa(P＜0. 01). Transient hypotension ( SBP ＜ 10. 7 kPa ) occurred in 2 patients during the course of Sol administration. There were no significant changes of HR and blood pressure in the NS group. Conclusion It was safe and effective for sotalo l administration on SVT.     

Clinical manifestations and prevalence of different types of supraventricular tachycardia among Chinese.

Sixty-nine cases of paroxysmal supraventricular tachycardia (PSVT) were submitted to electrophysiological studies. The prevalence of different types of PSVT is as follows: 49% of the cases had atrioventricular reentry tachycardia (AV-RT), 14.5% atrioventricular nodal reentry tachycardia (AVN-RT), 28% AV + AVN - RT, and 8.5% other types. Altogether 77% in this group had atrioventricular accessory pathway, of which half are concealed pathway. Electrocardiographic characteristics during tachycardia give hints to diagnosis: (1) AV - RT has the fastest heart rate, with 62% 200 BPM or more, and 82% more than 188 BPM; (2) retrograde P waves can be detected in 64% of cases with AV bypass; (3) 50% of AV - RT shows QRS of bundle branch block pattern. Since accessory pathways are present in the majority of PSVT patients in China, the importance of treatment is stressed.

     

房室结内折返性心动过速的射频导管消融

目的：观察我科自开展射频消融以来对引起房室结内折返性心动过速(AVNRT)的慢径路射频消融的治疗效果。方法：分析自2001-05～2004-03在我科住院行射频消融慢径路的24例AVNRT的临床电生理特征、成功率、复发率、并发症等。结果：24例AVNRT中，23例慢-快型AVNRT。1例快-慢型AVNRT，他们的电生理特性不同，但射频消融成功率达96％。有1例损伤房室结，为2：1房室传导阻滞。但很快恢复为1；1正常房室传导。到目前为止无1例复发AVNRT。结论：经导管用射频消融AVNRT病人的慢径路，成功率高，并发症少，复发率低。是目前根治AVNRT的首选方法。     

房室结慢径路消融——有效放电过程的心电监测

【目的】探讨房室结慢径路消融有效放电过程心电监测的意义。【方法】58例慢-快型房室结折返性心动过速在有效靶点以低射频能量(15～25W)放电,监测心电变化,出现①交界区心律>150min     

Comparison of properties of slow pathway potential between successful and unsuccessful radiofrequency applications in patients who underwent catheter ablation for atrioventricular nodal reentrant tachycardia

Findings concerning selective slow pathway radiofrequency ablation for atrioventricular nodal reentrant tachycardia (AVNRT) using the slow pathway potential (SPP) guided method are reported. The electrogram at the SPP recording site showed double potentials consisting of the atrial potential (A) and SPP. However, SPP is usually recorded widely in the right atrial posteroseptal region. To examine whether there was any characteristic marker in the electrogram at the SPP recording site specific to successful RF application, the properties of SPP and its anatomical locations in both successful (S) (38 sites) and unsuccessful (UN) (28 sites) application sites were analyzed in 38 patients who underwent SPP-guided ablation. The distance between the upper margin of the coronary sinus ostium (UCSO) and the ablation catheter (ABL) (DUCSO-ABL) was shorter in S than in UN (2.3 +/- 6.3 mm vs. 9.0 +/- 5.2 mm below the level of UCSO, p < 0.001). The interval between A and SPP (A-SPP) was longer in S than in UN (44.2 +/- 9.9 msec vs. 24.0 +/- 7.0 msec, p < 0.001). RF applications at the more anterior sites with longer A-SPP were more successful than at other sites. The sensitivity and specificity of A-SPP (more than 40 msec) were superior to those of DUCSO-ABL (within 5 mm) as the marker for the successful application (sensitivity; 73.7% v.s. 68.4%, specificity; 100% v.s. 82.1%, respectively). In conclusion, the sites with longer A-SPP might be specific for successful ablation.     

射频消融治疗房室结折返性心动过速三例报告

经导管射频消融术（RFCA）治疗3例房室结折返性心动过速（AVNRT）患者。用大头电极导管（Mansfeild/Webester)进行标测和消融，射频电传为4000－16000J。射频消融结果3例均获成功。     

肾脏特异表达新基因Collectrin在大鼠5/6肾切除残余肾中的表达

目的　探讨肾脏特异性表达新基因Collectrin在大鼠 5 / 6肾切除残余肾组织中的表达变化 ,为Collectrin基因功能研究提供线索。方法　建立慢性肾衰大鼠 5 / 6肾切除模型 ,分为对照组( 10只 )、手术组 ( 12只 )和依那普利治疗组 ( 12只 ) ,采用逆转录 PCR和Western蛋白印迹、免疫组织化学技术检测手术后 2、8和 16周大鼠肾组织Collectrin的表达变化。结果　在对照组中 ,随着大鼠周龄的增长大鼠CollectrinmRNA表达逐渐减少。 2 ,8,16周分别为 ,1 6 9± 0 0 9,1 38± 0 0 4,1 2 1± 0 0 9,(P <0 0 5 ) ;在术后 2 ,8,16周 ,手术组 ( 2 33± 0 0 7,1 85± 0 2 0 ,1 47± 0 17)Collectrin表达明显高于对照组 ( 1 6 9± 0 0 9,1 38± 0 0 4,1 2 1± 0 0 9,P <0 0 5 ) ;经依那普利治疗后 ,Collectrin表达明显减少 ;手术组Collectrin的表达在手术后 2周明显增加 ,随着慢性肾衰的进展Collectrin的表达逐渐减少。 2 ,8,16周分别为 2 33± 0 0 7,1 85± 0 2 0 ,1 47± 0 17(P <0 0 5 )。Collectrin蛋白的表达情况与CollectrinmRNA表达情况相一致。结论　Collectrin的表达随大鼠周龄的增长而减少 ;在 5 / 6肾切除残余肾组织中 ,Collectrin的表达与肾脏的增生、肥大的病生理变化相关。     

人胎盘微绒毛膜的制备及其转铁蛋白受体研究

Human placenta microvillous membrane (PMM) was prepared by differential centrifugation and by sucrose gradient centrifugation, and the transferrin receptor (TfR) was studied using the receptor radioassay with 125I-transferrin as a radioligand. The factors affecting ligand-receptor binding reaction and the characteristics of TfR were also studied. The result showed that there was no significant differences (P > 0.1) in specific binding rates of 125I-transferrin to its receptor between the two membrane preparations, indicating that both of them could be used for TfR analysis, but the method of differential centrifugation was more simple and less time consuming. The study of TfR in sixty cases showed that the TfR binding sites on PMM and Bmax were 3.53 +/- 1.98 x 10(12) sites/mg membrane protein and 6.33 +/- 4.21 x 10(-12) mol/mg membrane protein, respectively. The Kd was 4.95 +/- 3.39 x 10(-9) mol/L, and the highest specific binding was 26% with nonspecific binding less than 3%. The conditions for ligand-receptor binding reaction were optimized when the concentrations of membrane protein and the 125I-transferrin in each test tube were 50 micrograms and 50,000 cpm (specific radioactivity being 2109 kBq/micrograms transferrin) respectively the incubation time was 30 min, and the concentration of polyethylene glycol added for separating B/F was 12% (W/V). transferrin binding to its receptor was characterized by high affinity, high specificity and being saturated.     

干扰素α治疗慢性乙型肝炎过程中外周血树突状细胞亚群的变化及疗效关系

目的观察α干扰素(IFNα)治疗慢性乙型肝炎(CHB)过程中外周血树突状细胞(DCs)亚群的变化及其与临床疗效的关系。方法慢性乙型肝炎患者25例,应用α干扰素治疗24周,随访24周。利用流式细胞技术对患者外周血mDC和pDC的百分比和绝对数进行随访观察。结果治疗有效组13例,无效组12例。IFNα治疗CHB患者24周时HBVDNA阴转率、HBeAg阴转率、抗HBe阳转率分别为35%、40%、10%;48周时分别为40%、33.3%、20%。外周血mDC和pDC的百分比和绝对数在IFNα治疗后均呈下降趋势。其中,治疗有效组患者在治疗前,治疗后12周、24周、48周时mDC和pDC绝对数分别为(16.5±5.51)×106/L、(9.86±5.2)×106/L、(9.20±3.19)×106/L、(10.0±3.64)×106/L和(5.91±2.35)×106/L、(4.25±2.00)×106/L、(3.30±1.55)×106/L、(4.32±1.59)×106/L,分别进行多组间方差分析,均有统计学意义;无效组患者在治疗前,治疗后12周、24周、48周时mDC和pDC绝对数分别为(14.4±6.62)×106/L、(14.0±5.27)×106/L、(10.40±4.6)×106/L、(12.3±5.23)×106/L和(5.10±1.72)×106/L、(4.06±1.67)×106/L、(3.89±1.25)×106/L、(4.06±8.12)×106/L,经统计学处理,均无统计学意义。结论FNα治疗可以获得持续性病毒学及生化学应答。IFNα治疗可导致体内     

射频能量时间递增法治疗房室结折返性心动过速

目的：评估射频能量时间递增法治疗４０ 例房室结内折返性心动过速的疗效及安全性。　方法：标测到理想的慢径路靶点后,从小功率（１０～１５ Ｗ）、短时间（５～１０ ｓ）放电开始,如出现交界区早搏或交界区心律,逐渐增加放电功率（２０～２５ Ｗ）和持续时间（３０～６０ ｓ）,并密切观察房室传导阻滞的迹象和先兆。　结果：临床治愈率９７．５％ ,无一例产生严重并发症。　结论：射频能量时间递增法是一种安全、高效的治疗方法。     

Occurrence of atrioventricular block during supraventricular tachycardia: What is its possible mechanism?

A female patient was admitted to our hospital for catheter ablation arising from paroxysmal supraventricular tachycardia (PSVT). In the laboratory, PSVT (the earliest retrograde atrial activation at the coronary sinus ostium) with intermittent atrioventricular (AV) block could be induced repeatedly. The tachycardia could be terminated during ventricular pacing without retrograde conduction to the atria. Therefore, orthodromic AV reciprocating tachycardia (AVRT) and atrial tachycardia (AT) could be ruled out and AV nodal re-entrant tachycardia (AVNRT) was subsequently considered. Initial attempts using slow or intermediate AV nodal ablation failed to cure the tachycardia. We considered the possibility of orthodromic AV reciprocating tachycardia (AVRT) with AV block occurring during the tachycardia. The tachycardia was successfully terminated during the ablation of the right posteroseptal pathway at the coronary sinus ostium. We hypothesized about the possible explanation that might help to clarify the phenomenon of AV block during SVT in order to provide some guidance to other clinicians confronted with similar patient challenges in the future.     

独活中6种香豆素类成分在Caco-2细胞单层模型中的吸收转运研究

目的研究独活中6种香豆素类成分(伞形花内酯、甲氧基欧芹素、二氢欧山芹素、二氢欧山芹醇乙酯、当归醇-A和当归醇-B)在人源结肠腺癌细胞系Caco-2细胞单层模型的吸收和转运.方法采用Caco-2细胞单层模型研究6种香豆素类化合物由绒毛面(AP侧)到基底面(BL侧)和从BL侧到AP侧两个方向的转运过程,采用高效液相色谱法测定其在AP和BL侧的含量,计算表观渗透系数(apparent permeability coefficient,Papp),并与阳性对照药普萘洛尔和阿替洛尔进行比较.采用ATP耗竭剂碘乙酰胺和MRP2抑制剂MK571添加法探讨当归醇-B的转运机制.结果6种香豆素类成分皆以被动扩散为主要方式被Caco-2细胞吸收、转运.伞形花内酯、甲氧基欧芹素、二氢欧山芹素、二氢欧山芹醇乙酯、当归醇-A和当归醇-B由AP侧到BL侧的Papp分别为(2.679±0.263)×10-5、(1.306±0.324)×10-5、(0.595±0.086)×10-6、(0.293±0.041)×10-6、(1.532±0.444)×10-5和(1.413±0.243)×10-5cm/s;由BL侧到AP侧的Papp分别为(3.381±0.410)×10-5、(0.898±0.134)×10-5、(0.510±0.183)×10-6、(0.222±0.025)×10-6、(1.203±0.280)×10-5和(0.754±0.092)×10-5cm/s.在本实验条件下,易吸收的阳性对照药普萘洛尔由AP侧到BL侧的Papp值为2.18×10-5cm/s,不易吸收的阳性对照药阿替洛尔由AP侧到BL侧的Papp值为2.77×10-7cm/s.上述6个香豆素类化合物中,伞形花内酯、甲氧基欧芹素、当归醇-A和当归醇-B的Papp值与普萘洛尔的Papp值在一个数量级;二氢欧山芹素和二氢欧山芹醇乙酯的Papp值在易吸收和不易吸收的阳性对照药之间.以EBSS代替HBSS作为转运介质,在碘乙酰胺和MK571存在下,当归醇-B从AP侧到BL侧和从BL侧到AP侧转运的Papp值与HBSS为转运介质的对照组相比皆没有统计学意义上的变化.回收率实验中,伞形花内酯的平均总回收率为(83.31±3.52)%、当归醇-A的平均总回收率为(77.39±7.38)%;甲氧基欧芹素、二氢欧山芹素和当归醇-B的平均总回收率在50%～65%之间,二氢欧山芹醇乙酯的平均总回收率低于10%.甲氧基欧芹素和二氢欧山芹素在Caco-2细胞中的蓄积率分别为(36.15±5.87)%和(53.90±4.39)%.结论6种香豆素皆以被动扩散为主要方式被Caco-2细胞单层吸收和转运;伞形花内酯、甲氧基欧芹素、当归醇-A和当归醇-B是良好吸收的化合物,二氢欧山芹素和二氢欧山芹醇乙酯的吸收性属中等.在Caco-2细胞中,甲氧基欧芹素和二氢欧山芹素有蓄积,二氢欧山芹醇乙酯具有代谢不稳定性.当归醇-B的转运不受转运介质EBSS(pH 6.5)的影响,碘乙酰胺或MK571的存在亦不影响当归醇-B在两个方向的转运.     

Influence of ovariectomy in the right ventricular contractility in heart failure rats

BACKGROUND: Clinical studies in postmenopausal women suggest that female hormones play an important role in maintaining healthy cardiovascular conditions. The objective of this study was to evaluate the influence of ovarian hormones in the right ventricle contractility in heart failure (HF) rats following myocardial infarction (MI). METHODS: Female Wistar rats were divided into four groups: healthy ovariectomized (OVX), ovariectomized with HF (OVX-HF), HF, and sham operated (SHAM). Ovariectomy was performed in 10-week-old rats, and MI was induced 1 week later. Eight weeks after MI, right ventricular (RV) performance was analyzed using RV strip preparations. RESULTS: Ovariectomy did not change the infarct size (HF: 42 +/- 3.5 vs. OVX-HF: 39 +/- 1.5%). In the presence of isoproterenol (ISO) and calcium, the isometric force was reduced in both HF groups. Ovariectomy did not modify the positive inotropic parameter in the control and in HF rats. Time to peak tension (TPT) was prolonged in both ovariectomized groups compared to SHAM (ISO 10(-7) M OVX: 125 +/- 12( *); SHAM: 81 +/- 4; HF: 87 +/- 4; OVX-HF: 102 +/- 6( *) msec, ( *)p <0.01 vs. SHAM), and relaxation time (RT) was prolonged in OVX (270 +/- 16( *) msec) and OVX-HF (241 +/- 10( *) msec) vs. SHAM (197 +/- 6 msec; ( *)p <0.01 vs. SHAM). CONCLUSIONS: We conclude that the absence of female ovarian hormones during nine weeks does not influence the right ventricle positive inotropic response, but it prolongs the time of contraction and relaxation in normal and in HF rats following MI.     

葛根素对凝血酶诱导的血管平滑肌细胞增殖的影响

目的观察葛根素对凝血酶诱导的血管平滑肌细胞(VSMC)增殖的影响,对原癌基因c-fos和bc l-2蛋白质以及凝血酶受体(TR)mRNA表达的作用。方法以细胞计数法,流式细胞仪测定DNA含量,细胞周期分析法观察凝血酶及葛根素对VSMC增殖和DNA合成的影响。在凝血酶及葛根素作用24 h后,用W estern印迹法检测c-fos和bc l-2蛋白表达,以半定量逆转录聚合酶链式反应(RT-PCR)检测TR mRNA的表达。结果凝血酶对VSMC有明显促增殖作用,促增殖效应在24 h末达峰值(细胞计数凝血酶组8.64×104/m l±0.12×104/m l,对照组4.20×104/m l±0.11×104/m l,P<0.05),且凝血酶浓度在0.1~1.0 U/L之间呈剂量依赖关系;葛根素呈剂量依赖性地抑制凝血酶诱导的细胞增殖、DNA合成以及VSMC c-fos和bc l-2蛋白的表达(葛根素浓度为1.5×10-3mol/L时,抑制率分别为42.6%±5.2%、58.2%±7.9%、44.5%±7.5%和39.6%±6.4%,均P<0.05);高浓度(1.5×10-3mol/L)的葛根素可显著抑制凝血酶诱导的TR mRNA上调(抑制率为17.6%±1.7%,P<0.05)。结论葛根素能抑制凝血酶诱导的VSMC增殖,这可能与其抑制c-fos和bc l-2蛋白有关,并部分与其抑制TR mRNA表达有关。     

射频消融治疗房室结折返型心动过速

目的：旨在研究和评价射频导管消融治疗房室结返型心动过速的安全性和有效性。方法：病例来源于１９９３年４月至１９９７年４月在心内科住院治疗的心动过速病人，共２８例，男性１５例，女性１３例，年龄１２至６７岁，患者均经心电生理盐证实后行射频导管消融。结果：所有患者经射频导管消融后均获成功，随访３～６个月无１例复发，１例出现Ⅲ度房室传导阻滞，结论：射频过程中出现交界性心律并逐渐减少是成功的征象，消融治疗房室     

油茶皂苷C对心肌细胞缺氧/复氧损伤的保护作用及其机制

目的 探讨油茶皂苷C（CS—c）预处理对培养乳鼠心肌细胞缺氧／复氧（A／R）损伤的保护作用及作用机制。方法 采用培养3—4d的SD大鼠心肌细胞,随机分为5组（每组8孔）：正常对照组,单纯缺影复氧组（A／R）,缺氧预适应组（AP）,油茶皂苷C预处理（CS—C）,格列苯脲预处理组（Glib）。采用心肌细胞缺氧／复氧损伤模型,各组于复氧1h时进行以下指标检测：（1）心肌细胞存活率;（2）培养液中乳酸脱氢酶（LDH）含量;（3）透射电镜观察心肌细胞超微结构改变。结果 与对照组比较,A／R组LDH含量（57．8U／L±6．4U／L）高于对照组（12．3U／L±1．7U／L）,差异有统计学意义（P〈0．01）,心肌细胞存活率（51．0％±1.9％）低于对照组（92．0％±2．0％）,差异有统计学意义（P〈0．01）,细胞超微结构损害明显;CS—C预处理组LDH含量（39．8U／L±3．9U／L）、心肌细胞存活率（76．4％±3．5％）低于A／R组（P〈0．01）,其结果与AP组（分别为32．4U／L±5．2U／L,78．0％±2．0％,P〉0．05）相似,Glib组LDH含量（55.8U／L±5．0U／L）高于CS—C预处理组、心肌细胞存活率（54．1％±3.7％）低于CS-C预处理组（P〈0．05）。结论 CS—C预处理抗乳鼠心肌细胞缺氧／复氧损伤作用与缺氧预适应作用相似,其保护作用可能与KATP^＋,通道开放有关。     

Prolonged ventricular action potential duration due to nitric oxide release

BACKGROUND: Our previous study has demonstrated that increased intracoronary perfusion leads to a flow-dependent inversion of T waves on body surface ECG. However, whether increased coronary flow influences ventricular action potential duration measured directly from myocardium is unknown. METHODS: In six pentobarbital-anesthetized sheep, fresh arterial blood was injected into the left circumflex coronary (LCX) artery at a rate of 6 and 10 mL/min, respectively, in the presence of normal coronary flow. Activation-recovery interval (ARI), an estimate of ventricular action potential duration, was measured from epicardial ECGs acquired from the LCX territory. RESULTS: The intracoronary injection prolonged ARI by an average of 21 +/- 9 and 33 +/- 14 msec, respectively. After pre-treatment with nitro-l-arginine, a nitric oxide synthase inhibitor, intracoronary injection at the rate of 6 and 10 mL/min lead to an ARI increase of 3 +/- 2 msec (p >0.05) and 11 +/- 6 msec (p <0.05) respectively. CONCLUSIONS: An increase in coronary flow prolongs ventricular action potential duration in the intact sheep heart. Nitric oxide mediates the injection-induced increase in action potential duration.