Frankl W S, Poole-Wilson P A
J Cardiovasc Pharmacol. 1981 May-Jun;3(3):554-65. doi: 10.1097/00005344-198105000-00014.
Thiopental in concentrations of 28 and 227 mumoles/liter reduced the tension developed by isolated rabbit ventricular myocardium by 50 and 80%, respectively. The effect was rapid, reversible, and independent of heart rate. Thiopental (227 mumoles/liter) inhibited influx and efflux of potassium to the same extent, so that no net gain or loss occurred. Calcium influx and efflux were also reduced, but calcium was not displaced from the myocardium in association with the decline of tension. The maximum rate of depolarization of the action potential and the time to 50% repolarization were decreased, but resting membrane potential, amplitude, and time to 90% depolarization were unchanged. The negative inotropic effect of thiopental appears to be due to reduced availability of calcium to the myofibrils.
浓度为28和227微摩尔/升的硫喷妥钠分别使离体兔心室肌产生的张力降低了50%和80%。该作用迅速、可逆，且与心率无关。硫喷妥钠（227微摩尔/升）同等程度地抑制钾的内流和外流，因此没有净增减。钙的内流和外流也减少，但随着张力的下降，钙并未从心肌中被置换出来。动作电位的最大去极化速率和至50%复极化的时间缩短，但静息膜电位、幅度和至90%去极化的时间未变。硫喷妥钠的负性肌力作用似乎是由于肌原纤维可利用的钙减少所致。
