Kapitola J, Vilimovská D
Physiol Bohemoslov. 1981;30(4):347-51.
In two identical experiments, A and B, we studied the effect of the simultaneous l.v. injection of propranolol (Inderal, 0.5 mg/kg) on the circulatory effects of triiodothyronine (T3 500 microgram/kg i.v. 3 hours before measuring). The two substances act at different rates and so the blocking effect of propranolol preceded the development of the circulatory effects of T3. Cardiac output was measured by the Evans blue dilution method, the heart rate was calculated from the ECG recording and blood pressure was measured with a mercury manometer; stroke volume and total peripheral vascular resistance were also calculated. The isolated injection of T3 was followed by a significant increase in cardiac output (experiment A: 129%, B: 118%) and stroke volume (A: 125%, B: 118%) and by a drop in total peripheral vascular resistance (A: 82%, B: 85%). There was no change, in this early phase, in the heart rate or blood pressure. No changes were found 3 hours after the isolated administration of Inderal (the maximum effect of propranolol is attained in 30-60 min). During the same period, the above initial effects of T3 were completely suppressed by the simultaneous injection of Inderal. These results were probably related to the experimental conditions (early and not very marked changes after T3), but they demonstrate that the initial effects of T3 on cardiac performance and on the peripheral blood vessels can be completely suppressed by a block of beta receptors. From this it can be concluded that beta-adrenergic regulation is an important part of the mechanism of the early haemodynamic action of T3.
在两项相同的实验A和B中，我们研究了静脉同时注射普萘洛尔（心得安，0.5毫克/千克）对三碘甲状腺原氨酸循环效应的影响（在测量前3小时静脉注射三碘甲状腺原氨酸500微克/千克）。这两种物质作用速率不同，因此普萘洛尔的阻断作用先于三碘甲状腺原氨酸循环效应的出现。心输出量通过伊文思蓝稀释法测量，心率根据心电图记录计算得出，血压用汞柱血压计测量；同时还计算了每搏输出量和总外周血管阻力。单独注射三碘甲状腺原氨酸后，心输出量（实验A：增加129%，实验B：增加118%）和每搏输出量（实验A：增加125%，实验B：增加118%）显著增加，总外周血管阻力下降（实验A：下降82%，实验B：下降85%）。在这个早期阶段，心率和血压没有变化。单独给予心得安3小时后未发现变化（普萘洛尔在30 - 60分钟达到最大效应）。在同一时期，同时注射心得安可完全抑制三碘甲状腺原氨酸上述的初始效应。这些结果可能与实验条件有关（三碘甲状腺原氨酸注射后早期且变化不太明显），但它们表明三碘甲状腺原氨酸对心脏功能和外周血管的初始效应可被β受体阻断完全抑制。由此可以得出结论，β - 肾上腺素能调节是三碘甲状腺原氨酸早期血流动力学作用机制的重要组成部分。
