Effects of BmKIM on sodium current of isolated cardiomyocytes, transmembrane action potential and aconitine induced arrhythmia in vivo in rabbits / 中华心血管病杂志

<p><b>OBJECTIVE</b>To investigate the effects of recombinant BmKIM (poly-peptide derived from Asian Scorpion Buthus martensi Karsch) on the sodium current (I(Na)) of isolated ventricular myocytes, transmembrane action potential and aconitine induced arrhythmia in vivo in rabbits.</p><p><b>METHODS</b>Ventricular myocytes were enzymatically dissociated from adult rabbits. Whole-cell patch-clamp technique was used to record voltage-dependent I(Na). Standard transmembrane action potentials in rabbit hearts in vivo were recorded by using floating glass microelectrodes. Incidence of arrhythmias, the early after depolarization (EAD) and/or delay after depolarization (DAD) were measured in vivo in rabbits post aconitine (100 microg/kg, iv) in the absence or presence of BmKIM (50 microg/kg iv).</p><p><b>RESULTS</b>(1) BmKIM significantly inhibited I(Na) in a voltage-dependent manner and significantly shifted the I-V curves of I(Na) upward. BmKIM left shifted the inactivation curve of I(Na) and voltages at 50% inactivation of I(Na) were changed from (-70.8 +/- 2.6) mV to (-84.8 +/- 3.5) mV (P < 0.05). BmKIM prolonged the recovery of inactivation of I(Na). In the presence of BmKIM, the time constants of recovery (both tau(f) and tau(s)) of I(Na) were significantly prolonged from (28.9 +/- 6.1) ms and (107 +/- 21.6) ms in control group to (54.2 +/- 7.9) ms (P < 0.05) and (211.1 +/- 34.6) ms (P < 0.01), respectively. (2) BmKIM significantly shortened 50% and 90% of action potential duration (APD(50) and APD(90)), and reduced action potential amplitude (APA), declined maximum up stroke velocity of action potential (V(max)) in vivo. The Q-T duration was shortened and heart rate significantly increased post BmKIM injection. (3) Incidence of aconitine induced ventricular arrhythmias (77.8%) was significantly reduced by BmKIM (22.2%, P < 0.01).</p><p><b>CONCLUSIONS</b>BmKIM significantly blocked I(Na) through affecting the inactivated state of I(Na) in rabbit ventricular myocytes. BmKIM could attenuate the influx of I(Na), therefore shorten action potential duration and reduce action potential amplitude and reduce the incidence of aconitine induced arrhythmias.</p>

Study on linkage between polymorphism of interleukin 6 gene -572C/G and susceptibility to myocardial infarction / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To observe the polymorphism and gene frequency of interleukin 6 (IL6) gene -572C/G in Chinese Han nationality population, that associating with susceptibility to myocardial infarction(MI) and impacting on the extent of coronary artery lesions; to analyze the function of IL6 gene -572C/G polymorphism.</p><p><b>METHODS</b>With PCR-RFLP method, IL6 gene -572C/G polymorphism was genotyped to 232 MI patients and 260 healthy adults. The effect of IL6 gene -572C/G polymorphism was observed to the extent of coronary artery lesions and the ability of IL6 production from peripheral blood mononuclear cells (PBMC).</p><p><b>RESULTS</b>There was IL6 gene -572C/G polymorphism in Chinese Hans. -572CG+GG genotype and G allele were more frequent in patients than in controls (P< 0.01). The relative risk for G allele carrier to suffer from MI was 1.68 times of CC genotype individual (95%CI 1.17-2.41, P< 0.01). However, the distribution of IL6 gene -572C/G polymorphism was no significant difference among patients with single-vessel, two-vessel and three-vessel lesions (P> 0.05). After PBMC cultured for 24 hours, the IL6 concentration in supernatant was significantly higher in subjects with CG genotype than those with CC genotype (P< 0.05).</p><p><b>CONCLUSION</b>IL6 gene -572G allele may be a genetic susceptibility factor to MI attack of Chinese Hans population, and related to the high expression of IL6.</p>

Interleukin-6-597G/A and -572C/G polymorphisms and risk of coronary heart disease / 中华心血管病杂志

<p><b>OBJECTIVE</b>To explore the relationship between interleukin-6 (IL-6) gene polymorphisms and the risk of coronary heart disease (CHD).</p><p><b>METHODS</b>IL-6/-597G/A and -572C/G polymorphisms were genotyped in 245 CHD patients and 260 healthy adults by PCR-RFLP. Serum IL-6 level was examined by ELISA. Logistic regression was performed to observe the relationship between IL-6/-572C/G polymorphism and other risk factors of CHD.</p><p><b>RESULTS</b>IL-6/-597G/A genotype was similar between the two groups. The frequencies of IL-6/-572C/G genotype and G allele were more frequent in patients with CHD than that in controls (P < 0.01). Compared with CC genotype, the relative risk for CHD in people with CG and GG genotypes was 1.46 (95% CI: 1.01 - 2.10, P < 0.05) and 5.19 (95% CI: 1.69 - 15.89, P < 0.01), respectively. The serum levels of IL-6 were similar between carriers of the IL-6/-572G allele and patients with CC genotype (P > 0.05). IL-6/-572 C/G is related to total cholesterol (OR 1.76, 95% CI: 1.05 - 3.16, P < 0.05) and triglyceride (OR = 2.51, 95% CI: 1.04 - 6.45, P < 0.05), respectively.</p><p><b>CONCLUSION</b>IL-6/-597G/A polymorphism was not associated with susceptibility to CHD, but IL-6-572C/G polymorphism may be a possible genetic susceptibility factor for CHD in Chinese Hans population.</p>

The role of isoprenaline-induced, calcium-activated transient outward chloride current in atrial electrical remodeling of rabbit / 中华心血管病杂志

<p><b>OBJECTIVE</b>To investigate the relationship between the changes of the L-type calcium current (I(Ca, L)) and the calcium-activated transient outward chloride current (I(Cl, Ca)), and the repolarization characteristic of action potential in phase 1 under isoprenaline (ISO) stimulation in atrium myocytes of rabbit.</p><p><b>METHODS</b>Atrium myocytes were obtained by enzymatic dissociation from a section of atrial free wall. The membrane currents and action potential were recorded by the whole-cell patch-clamp technique.</p><p><b>RESULTS</b>After recording I(Ca, L), atrium myocytes were perfused with ISO (1 micromol/L) immediately. Five minutes later, a transient outward current (I(to)) was significantly induced, and the peak of I(to) was gradually increased while I(Ca, L) gradually decreased with increasing in clamp voltage. The I(to) was resistant to 4-AP (3 mmol/L) but sensitive to DIDS (150 micromol/L, Cl(-) channel blocker). This current was blocked by CdCl(2) (200 micromol/L, Ca(2+) channel blocker). The elicited rate of I(to) was 91.67% (P < 0.05). (2) The shape of AP was like an inverse triangle with no plateau in Phase 2 after ISO (1 micromol/L) perfusion. Moreover, compared to the parameters of control group, APD(50) and APD(90) were significantly shortened from (65.4 +/- 4.2) ms and (95.8 +/- 3.8) ms to (12.8 +/- 3.8) ms and (27.0 +/- 4.7) ms, and reduced to 80.46% and 71.87%, respectively (P < 0.01, n = 12). 4-AP (3 mmol/L) had on obvious effect on the shape of AP, however, the plateau of AP in phase 2 was recovered by DIDS (150 micromol/L) perfusion, APD(50) and APD(90) were (41.1 +/- 4.5) ms and (79.6 +/- 3.4) ms respectively. Compared to the parameters of control group, there were no significant differences (P > 0.05, n = 12). These results indicated that ionic transport were changed by ISO perfusion in atrium myocytes and I(to) played an important role in the phase 1 repolarization of AP.</p><p><b>CONCLUSIONS</b>Before ISO administration, we could only observe I(Ca, L) in atrium myocytes of rabbit. After isoproterenol intervention, certain intracellular ionic consistency and membrane ionic channels were changed. Calcium activated chloride channel and I(to2) revealed obvious predominance which shorten APD significantly. Action potential showed a triangle with no plateau, suggesting an electrical remodeling in atrium myocytes. The remodeling of ionic channel is related possibly with the opening of Ca(2+)-activated Cl(-) current, which maybe the electrophysiological base of reentrant atrial tachycardia.</p>

The distribution of gene polymorphisms in the intron 2 and exon 2 of interleukin-1 receptor antagonist and their correlation with the serum lipoprotein level / 中华流行病学杂志

<p><b>OBJECTIVE</b>To study the distribution of variable numbers of tandem repeat (VNTR) polymorphism in the intron 2 and the single nucleotide polymorphism (SNP) at position +8006 in the exon 2 of IL-1RN in healthy Chinese Han Population of Wuhan province and to analyze their correlation with the serum lipoprotein level.</p><p><b>METHODS</b>IL-1RN (VNTR) and IL-1RN (+8006) polymorphisms were detected by PCR and PCR-RFLP methods in 251 healthy Chinese Han Population of Wuhan, and the levels of serum lipoprotein, IL-1 and IL-1Ra were inspected simultaneously.</p><p><b>RESULTS</b>In IL-1RN (VNTR), allele I appeared most common, then allele II, and allele IV was rare. At the position of IL-1RN (+8006), allele T was most commonly seen followed by allele C. Allele II of IL-1RN (VNTR) always existed with allele C of IL-1RN (+8006). The levels of serum lipoprotein, IL-1 and IL-1Ra were not different among the different genotypes of the two polymorphisms.</p><p><b>CONCLUSION</b>There were two gene polymorphisms in the intron 2 and exon 2 of IL-1RN, which were not correlated with the levels of serum lipoprotein, IL-1 and IL-1Ra. However, there seemed to be a linkage disequilibrium between IL-1RN (VNTR) and IL-1RN (+8006).</p>

Estradiol in inhibition of proliferation ofvascular smooth muscle cells after balloon injury / 中国临床药理学与治疗学

Aim To investigate estradiol inhibition of neointimal proliferation after rat carotid artery balloon injury. Methods Eight to ten-week-old SD rats (male,n=21,female,n=21) were divided into intact control(n=7),gonadectomy control(n=7) and estradiol (n=7, gonadectomy)groups in each sex. Left carotid artery was not injured with 2.0 F PTCA balloon until estradiol was injected for three days. Rats were killed 2 wk after injury. Neointimal areas and media area, ratios of intimal areas/media areas were measured with computer. Results Male neointimal areas and ratios of intimal areas /media areas in estradiol group were less than those in intact control group significantly(all P0.05). Conclusions Estrdiol inhibits neointimal proliferation after the gonadectomy in rats undergoing carotid artery balloon injury.