Pucelík P, Holická M, Lässigová M, Jezek K
Physiol Bohemoslov. 1984;33(1):49-57.
Experiments were carried out on the working myocardium of the right heart ventricle of newborn and adult rabbits, guinea-pigs, dogs and albino rats. In the dog, the guinea-pig and the rabbit, after ten action potentials (AP) elicited with 1 Hz frequency we always interpolated an extrasystole at an interval (TE) of 100-900 ms. In albino rats we used a basic frequency of 2 Hz and a TE of 30-370 ms from the last regular AP. Using glass microelectrodes, we recorded the extrasystolic AP (EAP) and the next subsequent AP (2AP). The results were evaluated by constructing graphs of the correlations of the duration of the plateau phase (D0) to TE and of the duration of repolarization to -60 mV level (D60) to the TE. In the myocardium of newborn rabbits, guinea-pigs and dogs, with short TE both D0 and D60 of the EAP are shorter than in the steady state (SS), while for the 2AP the same parameters are influenced only a little. As the TE lengthens, the EAP gradually acquire a length corresponding more to the SS. With TE longer than half the duration of the cycle in the steady state the EAP return to normal, while the 2AP become shorter. The effect of extrasystole on the rat EAP and 2AP diminished with advancing age. In the myocardium of adult rabbits and adult guinea-pigs, and slightly in the myocardium of adult dogs and newborn rats, we observed that the duration of the EAP, with certain TE, was greater than in the steady state.(ABSTRACT TRUNCATED AT 250 WORDS)
实验在新生及成年兔、豚鼠、犬和白化大鼠的右心室工作心肌上进行。在犬、豚鼠和兔中，以1Hz频率诱发10个动作电位（AP）后，我们总是在100 - 900ms的间隔（TE）处插入一个期外收缩。在白化大鼠中，我们使用2Hz的基础频率，且从最后一个正常AP起的TE为30 - 370ms。使用玻璃微电极，我们记录了期外收缩动作电位（EAP）和随后的下一个动作电位（2AP）。通过构建平台期持续时间（D0）与TE以及复极化至 - 60mV水平的持续时间（D60）与TE的相关性图表来评估结果。在新生兔、豚鼠和犬的心肌中，当TE短时，EAP的D0和D60均比稳态（SS）时短，而对于2AP，相同参数仅受到轻微影响。随着TE延长，EAP逐渐获得更接近SS的长度。当TE长于稳态周期持续时间的一半时，EAP恢复正常，而2AP变短。期外收缩对大鼠EAP和2AP的影响随着年龄增长而减弱。在成年兔和成年豚鼠的心肌中，以及在成年犬和新生大鼠的心肌中稍有体现，我们观察到在特定TE下，EAP的持续时间比稳态时长。（摘要截断于250字）
