Opitz H
Acta Biol Med Ger. 1980;39(5):561-9.
In strip preparations from the right ventricle of the guinea pig heart, potentiation phenomena due to varied pacing rate (frequency potentiation FP) or paired stimulation (paired pulse potentiation PPP) are studied with respect to contractile strength and dynamics. Heart rate or interstimulus interval of paired stimulation were modulated both stepwise and sinusoidally. Steady state characteristics of FP as well as PPP prove to be linear in a broad range. FP is enhanced by increasing rate, whereas PPP is diminished by increasing interval. Paired stimulation is always more effective than single stimulation at double rate. Effects upon action potential are negligible. The response of PPP to interval steps are first order transients, whereas rate steps produce on/off response of FP, opposite to step direction, with subsequent staircase. Frequency response characteristics of FP and PPP yield in first order transfer functions: for PPP with dead time, and for FP with negative derivative action. After substitution of Ca++ by Sr++ ions, the negative derivative term of FP disappears, whereas positive staircase remains. By means of a compartment hypothesis of electromechanical coupling in the mammalian myocardium the mode of action of the potentiation phenomena and their differences are interpreted, and the obtained dynamic parameters are attributed to presumably underlying Ca transport processes within the cell.
在豚鼠心脏右心室的条带制备物中，研究了不同起搏速率（频率增强，FP）或成对刺激（成对脉冲增强，PPP）对收缩强度和动力学的增强现象。心率或成对刺激的刺激间隔以逐步和正弦方式进行调制。FP以及PPP的稳态特性在很宽的范围内被证明是线性的。FP通过增加速率而增强，而PPP通过增加间隔而减弱。在双倍速率下，成对刺激总是比单次刺激更有效。对动作电位的影响可以忽略不计。PPP对间隔步长的响应是一阶瞬态，而速率步长产生与步长方向相反的FP的开/关响应，并随后出现阶梯现象。FP和PPP的频率响应特性产生一阶传递函数：对于具有死区时间的PPP，以及对于具有负导数作用的FP。在用Sr++离子替代Ca++后，FP的负导数项消失，而正阶梯现象仍然存在。借助于哺乳动物心肌中机电耦合的隔室假设，解释了增强现象的作用方式及其差异，并将获得的动态参数归因于细胞内可能潜在的Ca转运过程。
