Schmidt T A, Larsen J S, Shannon R P, Komamura K, Vatner D E, Kjeldsen K
Department of Cardiothoracic Surgery RT, Rigshospitalet, University of Copenhagen, Denmark.
Basic Res Cardiol. 1993 Nov-Dec;88(6):607-20. doi: 10.1007/BF00788878.
The present study evaluates 3H-ouabain binding site (Na,K-ATPase) concentration in left ventricular myocardium of dogs with heart failure induced by tachycardia as a result of ventricular pacing. Samples of left ventricle were obtained from 10 dogs exposed to pacing of 240 beats/min for 3 to 4 weeks and eight sham-operated controls. Na,K-ATPase was quantified using vanadate facilitated 3H-ouabain binding to intact samples. At time of sacrifice paced dogs showed clinical signs of heart failure, a significant 257% increase in left ventricular end diastolic pressure and a significant 46% decrease in left ventricular dP/dt compared with control. There was no significant change in left ventricular mass. 3H-ouabain binding concentration was significantly reduced by 16%. Evaluation of 3H-ouabain binding kinetics revealed no significant difference between myocardium from paced and control dogs: Equilibrium binding conditions were at the various concentrations used obtained after similar incubation time; nonspecific uptake and retention of 3H-ouabain was 0.9-0.8% of total uptake and retention obtained in the standard assay; apparent dissociation constant (KD) was 6.5 x 10(-8)-6.6 x 10(-8) mol/l; loss of specifically bound 3H-ouabain during washout at 0 degrees C occurred with a half-life time (T1/2) of 120 and 121 h. Hence, total 3H-ouabain binding site concentration in left ventricular myocardium was (mean +/- SEM) 1110 +/- 56 and 1317 +/- 68 pmol/g wet weight, 8.54 +/- 0.43 and 10.05 +/- 0.52 pmol/mg protein, and the total amount of 3H-ouabain binding sites in the entire left ventricle 121 +/- 6 and 162 +/- 8 nmol in paced (n = 10) and control (n = 8) dogs (p < 0.05), respectively. In conclusion, the present study reports a significant reduction in left ventricular myocardium 3H-ouabain binding site concentration in tachycardia induced heart failure. This observation supports the concept of a relationship between Na,K-ATPase concentration and contractile capacity and may be of pathophysiological importance in tachycardia and heart failure.
本研究评估了因心室起搏导致心动过速而诱发心力衰竭的犬左心室心肌中3H-哇巴因结合位点（Na，K-ATP酶）的浓度。从10只接受240次/分钟起搏3至4周的犬以及8只假手术对照犬获取左心室样本。使用钒酸盐促进3H-哇巴因与完整样本的结合来定量Na，K-ATP酶。处死时，起搏犬表现出心力衰竭的临床症状，与对照组相比，左心室舒张末期压力显著增加257%，左心室dP/dt显著降低46%。左心室质量无显著变化。3H-哇巴因结合浓度显著降低了16%。对3H-哇巴因结合动力学的评估显示，起搏犬和对照犬心肌之间无显著差异：在相似的孵育时间后，在所使用的各种浓度下达到平衡结合条件；3H-哇巴因的非特异性摄取和保留量为标准测定中总摄取和保留量的0.9 - 0.8%；表观解离常数（KD）为6.5×10（-8）- 6.6×10（-8）mol/l；在0℃冲洗期间，特异性结合的3H-哇巴因损失的半衰期（T1/2）为120和121小时。因此，起搏犬（n = 10）和对照犬（n = 8）左心室心肌中3H-哇巴因结合位点的总浓度（平均值±标准误）分别为1110±56和1317±68 pmol/g湿重、8.54±0.43和10.05±0.52 pmol/mg蛋白质，整个左心室中3H-哇巴因结合位点的总量分别为121±6和162±8 nmol（p < 0.05）。总之，本研究报告了心动过速诱发的心力衰竭中左心室心肌3H-哇巴因结合位点浓度显著降低。这一观察结果支持了Na，K-ATP酶浓度与收缩能力之间存在关系的概念，并且可能在心动过速和心力衰竭中具有病理生理学重要性。
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