Effects of hyperthyroidism on the electrophysiological characteristics between atrium and gap junction between atrium and pulmonary vein / 中华急诊医学杂志

Objective To investigate the effects of hyperthyroidism on the electrophysiological characteristics of atrium and gap junction between atrium and pulmonary vein.Methods Twenty-four rabbits were randomly divided into control group and hyperthyroid group.Atrium and pulmonary vein were dissected after the atrial effective refractory period (AERP)was measured.Connexin 43(Cx43)and Counexin 40(Cx40)protein and mRNA were determined by Western blot and semi-quantitative reverse transcription-polymerase chain reaction,respectively.Results In comparison with control group,AERP and rate adaption of AERP in hyperthyroid group were significantly shorter than that of control group( P＜0.01).The concentration of Cx43 protein in hyperthyroid group was significantly higher than that of control group,but Cx40 protein was significantly lower than that of control group(P＜0.05).The expression of Cx43 mRNA in atrium and pulmonary vein was found to be up-regulated in hyperthyroid group as compared with that of control group(P＜0.01). With the level of Cx40 mRNA,there was no significant difference between two groups.Conclusion Thyroid hormone could lead to remodeling of both atrial electrophysiology and gap junction between atrium and pulmonary vein.

Effect of acute coronary microembolization on microvascular injury and myocardial endothelin-1 levels / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To investigate the effect of coronary microemboliation (CME) on coronary microvascular injury and myocardial endothelin-1 (ET-1) level.</p><p><b>METHODS</b>CME was induced in 10 miniswines by selective infusion of microspheres (45 microm) into left anterior descending artery (LAD). The ET-1 level in coronary sinus was measured with radioimmunoassay. The microvascular integrity indicator CFR was measured by Doppler flow wire in LAD at baseline and after infusion of microspheres.</p><p><b>RESULT</b>Compared to the baseline, CFR decreased significantly with different doses of microspheres. ET-1 level increased significantly with doses of 5 x 10(4) and peaked with 10 x 10(4), and progressively decreased from doses of 12 x 10(4) to 15 x 10(4) microspheres. There was negative correlation between ET-1 and CFR (r=-0.31, P=0.02).</p><p><b>CONCLUSION</b>The extent of microvascular injury is not linearly related to the extent of microembolization, but it is closely associated with myocardial ET-1 level.</p>