心脏内外膜心肌细胞L-型钙电流对异丙肾上腺素刺激反应差异的机制  

The mechanism underlying the different response of L-type calcium current to isoproterenol stimulation between epicardium and endocardium

作　　者：陈静[1] 陈江斌[1] 徐林[1] 

机构地区：[1]武汉大学人民医院心血管内科,湖北武汉430060

出　　处：《中国心脏起搏与心电生理杂志》2013年第2期159-161,共3页Chinese Journal of Cardiac Pacing and Electrophysiology

基　　金：国家自然基金青年基金(项目编号:81100130);中央高校青年教师资助项目(项目编号:302274666)

摘　　要：目的探讨心脏内外膜心肌细胞L-型钙电流(ICa,L)对异丙肾上腺素(ISO)刺激反应差异产生的机制。方法急性分离小鼠心肌内、外膜细胞,用膜片钳记录ISO灌流前后内外膜ICa,L的大小。用环磷腺苷(cAMP)在胞内激活蛋白激酶A(PKA)后,记录ICa,L及L-型钡电流(IBa,L)。结果细胞外膜基础ICa,L大于内膜[9.9±0.7 pA/pF(n=6)vs 6.4±0.4 pA/pF(n=10),+10 mV,P<0.05]。ISO作用后ICa,L在内外膜均增大[18.9±1.7 pA/pF(n=6)vs 13.7±0.9 pA/pF(n=10),0 mV,P<0.05],但内膜ICa,L增加的幅度更高(102.3%±11.3%vs 81.9%±10.4%,P<0.05)。内外膜细胞在cAMP刺激后,跨膜梯度消失[19.5±0.9 pA/pF(n=9)vs 20.5±1.3 pA/pF(n=11),+10 mV,P>0.05],且内外膜IBa,L相似[20.1±1.8 pA/pF(n=10)vs 19.3±1.7 pA/pF(n=10),-10mV,P>0.05]。结论心脏内外膜ICa,L对ISO刺激反应的差异可能由内外膜PKA活性决定,与肾上腺素受体密度及细胞内钙活动无关。Objective To explore the mechanism underlying the different responses of L-type calcium current （ICa ,L ） to isoproterenol （ISO） stimulation between epicardium and endocardium. Methods Epicardium and endocardium were isolated from mouse hearts, and ICa ,L was recorded by patch clamp technique before and after ISO perfusion. In addition, ICa ,L and Is.＇ L were recorded after intracellular cyclic adenosine monophosphate （cAMP） stimulation. Results Basal ICa ,L in epicardium was larger than that in endocardium [9.9±0.7 pA/pF （n=6） vs 6.4±0.4 pA/pF （n= 10）, ＋10 mV, P〈0. 05 ]. After ISO perfusion, ICa ,L was increased both in epicardium and endocardium [ 18.9 ± 1.7 pA/pF （ n = 6） vs 13.7±0.9 pA/pF （n= 10）, 0 mV,P〈0.05], but the percentage increase of ICa ,L in endocardium was higher than that in epicardium （ 102.3 % ± 11.3 % vs 81.9% ± 10.4%, P〈0.05 ）. cAMP could blunted the epicardium-endocardium ICa ,L gra- dient [ 19.5 ±0.9 pA/pF （ n = 9） vs 20.5 ± 1.3 pA/pF （ n = 11 ）, ＋ 10 mV, P〉0.05 ] and Isa ,L gradient [ 20.1 ± 1.8 pA/pF （ n = 10） vs 19, 3 ± 1.7 pA/pF （ n = 10）, -10 mV,P〉0.05 ]. Conclusion The different responses of Ic,＇ L to ISO stimu- lation between epicardium and endocardium is determined by PKA activity, but not the density of β-adrenergic receptor or calcium-related process.

关 键 词：心血管病学 L-型钙电流 L-型钡电流 蛋白酶A 异丙肾上腺素 环磷腺苷 

分 类 号：R331.38[医药卫生—人体生理学]