Komai H, Redon D, Rusy B F
Department of Anesthesiology, University of Wisconsin, Madison.
Acta Anaesthesiol Scand. 1991 Jul;35(5):373-9. doi: 10.1111/j.1399-6576.1991.tb03313.x.
To see if the known properties of thiopental of reducing Ca2+ and K+ fluxes across the myocardial sarcolemma account for its arrhythmogenic action, we have evaluated the effect of the anesthetic on spontaneous contractile activity induced in isolated rabbit papillary muscles. Thiopental (20 mg/l) prolonged the duration of sustained automaticity induced by stimulation at 1-2 Hz in the presence of 1 mumol/l isoproterenol. Thiopental (10, 20 mg/l) shortened the delay before the onset of Ba(2+)-induced automaticity, which involves a decrease in a K+ current. The minimum concentration of Ba2+ required to induce automaticity was lowered by thiopental. Whether spontaneous activities were induced by high frequency stimulation in the presence of isoproterenol or by Ba2+, thiopental lowered the frequency of spontaneous beats. Thus, thiopental appears to have both arrhythmogenic and antiarrhythmic actions, and the former may be unmasked when catecholamines counteract the latter by increasing Ca2+ influx. Like thiopental, halothane (1.0%) decreased the frequency and force of Ba(2+)-induced automatic beats but, unlike thiopental, prolonged the delay before the onset of Ba(2+)-induced automaticity, indicating that halothane acts as a purely antiarrhythmic agent in this type of automaticity.
为了探究硫喷妥钠降低心肌肌膜钙钾离子通量的已知特性是否可解释其致心律失常作用，我们评估了该麻醉药对离体兔乳头肌诱导的自发收缩活动的影响。硫喷妥钠（20毫克/升）在1微摩尔/升异丙肾上腺素存在的情况下，延长了1 - 2赫兹刺激诱导的持续性自律性的持续时间。硫喷妥钠（10、20毫克/升）缩短了钡（2 +）诱导的自律性开始前的延迟时间，这涉及钾电流的降低。硫喷妥钠降低了诱导自律性所需的钡2 +的最低浓度。无论自发活动是由异丙肾上腺素存在下的高频刺激还是钡诱导的，硫喷妥钠都降低了自发搏动的频率。因此，硫喷妥钠似乎具有致心律失常和抗心律失常两种作用，当儿茶酚胺通过增加钙内流抵消后者时，前者可能会显现出来。与硫喷妥钠一样，氟烷（1.0%）降低了钡（2 +）诱导的自发搏动的频率和力量，但与硫喷妥钠不同的是，它延长了钡（2 +）诱导的自律性开始前的延迟时间，表明氟烷在这种类型的自律性中仅起抗心律失常作用。
