犬Marshall韧带心肌细胞电生理特性的研究

目的　研究Marshall韧带(ligamentofMarshall, LOM)内心肌细胞的电生理特性。方法　组织块酶解法分离犬LOM内单个心肌细胞,在倒置显微镜下直接比较细胞形态;采用全细胞膜片钳技术记录心肌细胞动作电位的时程 (APD90,APD50 )和振幅 (APA),测量ICa,L、Ito、IK1、IK、INa等离子电流密度。结果　LOM内有两种不同形态的心肌细胞:一种为短矩形,另一种为长杆形,两者的长宽比分别为 2 .99±0. 95和 12. 05±2 .41,P<0. 01。两种形态细胞均表现为快反应动作电位,短矩形细胞的APA(mV)、APD50 (ms)和APD90 (ms)均小于长杆形细胞,分别为 80. 02±3 .68比 91 .72±7. 56、69 .62±6 .33比 83. 14±3 .66和 107. 55±4 .25比 144. 00±5 .15,P<0 .05。两种细胞的INa、ICa,L、Ito、IK1等离子的电流密度差异有统计学意义。结论　Marshall韧带中肌细胞呈现两种形态,并且在动作电位及许多离子电流密度上存在差异,两者的细胞电生理呈不均一性。

Electrophysiology of cardiocytes in ligament of Marshall of canine

OBJECTIVE: To investigate electrophysiology of cardiocytes in ligament of Marshall. METHODS: The single cardiocytes obtained from ligament of Marshall were direct observed under inverted microscope. The cardiocyte action potential and current density of I(Na), I(Ca), L, I(to), I(K) and I(K1) were researched by whole-cell patch-clamp techniques. RESULTS: There were two different cadiomyocytes in ligament of Marshall, one was rod shape, the other was short-rectangle shape. The short-rectangle myocyte was short and thick; the rod myocyte was long and thin. The short-rectangle myocyte was more than rod myocyte. The length/width rate of short-rectangle myocyte was less than that of rod myocyte (2.99 +/- 0.95 vs 12.05 +/- 2.41, P < 0.01). The action potential of ligament myocytes was similar to fast responsive cells. The action potential amplitude (APA) and duration (APD) of short-rectangle cells were less than those in rod cells. APA (mV), APD(50) (ms) and APD(90) (ms) were respectively 80.02 +/- 3.68 vs 91.72 +/- 7.56, 69.62 +/- 6.33 vs 83.14 +/- 3.66 and 107.55 +/- 4.25 vs 144.00 +/- 5.15, P < 0.05. The ion current density of I(Na), I(Ca), L, I(to), I(K1) was different between the two kind cells. CONCLUSIONS: There are two different cardiocytes in ligament of Marshall. The action potential and ion current density of I(Na), I(Ca), L, I(to), I(K1) are different between the two kind cardiocytes.