Almeida A P, Alpoim N C, Freire-Maia L
Toxicon. 1982;20(5):855-65. doi: 10.1016/0041-0101(82)90073-3.
To study the cardiac effects induced by purified scorpion toxin (tityustoxin, TsTX), without circulatory and respiratory influences, isolated guinea pig hearts were used. Single injections of 10, 20 or 30 micrograms TsTX induced positive inotropic and chronotropic effects in the majority of the experiments. The inotropic effects were dose-dependent. Simultaneous recording of the electrical activity of the heart showed sinus tachycardia, T wave inversion and ST segment deviations. Sinus bradycardia and/or A-V block were recorded in some experiments, simultaneously with the positive inotropic effects. After these initial events, the larger dose of TsTX elicited periodic changes of heart rate (in 70% of the experiments) which were explained by wandering pacemakers. During these periodic changes in heart rate, the electrocardiogram showed sinus bradycardia, idioventricular rhythm, complete or partial A-V block, sinus tachycardia, sinus arrest and junctional rhythm. The coronary flow varied inversely with the inotropism and the cardiac rate, but the changes in flow were related mainly to the inotropism. The effects of TsTX on the electrocardiogram, inotropism and coronary flow spontaneously disappeared 15-20 min after toxin injection. The arrhythmias induced by TsTX were blocked either by propranolol or by atropine and are assumed to be due to the release of catecholamines and acetylcholine from postganglionic nerve fibers in the heart.
为研究纯化的蝎毒素（tityustoxin，TsTX）在无循环和呼吸影响情况下所诱发的心脏效应，采用了离体豚鼠心脏。单次注射10、20或30微克TsTX在大多数实验中诱发了正性肌力和变时性效应。正性肌力效应呈剂量依赖性。同时记录心脏电活动显示窦性心动过速、T波倒置和ST段偏移。在一些实验中，在出现正性肌力效应的同时记录到窦性心动过缓和/或房室传导阻滞。在这些初始事件之后，较大剂量的TsTX引发心率的周期性变化（在70%的实验中），这是由游走起搏点所解释的。在这些心率周期性变化期间，心电图显示窦性心动过缓、室性自主心律、完全或部分房室传导阻滞、窦性心动过速、窦性停搏和交界性心律。冠脉血流与心肌收缩力和心率呈反比变化，但血流变化主要与心肌收缩力有关。TsTX对心电图、心肌收缩力和冠脉血流的效应在毒素注射后15 - 20分钟自发消失。TsTX所诱发的心律失常可被普萘洛尔或阿托品阻断，推测是由于心脏节后神经纤维释放儿茶酚胺和乙酰胆碱所致。
