Schumann S
Arch Exp Veterinarmed. 1980;34(3):431-42.
The average heart rate induced to cattle by a maximum isoprenaline dose of 250 microgram/kg was 166 beats/minute. Such drastic shortening of heart rate intervals, PP, was accompanied by highly significant shortening of all other electrocardiographic segments, such as PQ, ST, and TP, as well as of QRS-time (initial ventricular variation). Isoprenaline, a synthetic sympathicomimetic, was compared to well-known results reported for the action of adrenalin and noradrenalin on heart rate and ECG of cattle, and it was found to cause much stronger acceleration of cardiac activity with more strongly shortened ECG segments. Such difference between the three catecholamines nonradrenaline, adrenalin, and isoprenaline was found to be attributable to differences in the stimulation of alpha-adrenergic and beta-adrenergic receptors. Isoprenaline did not produce any alpha-adrenergic effect, and so purely beta-adrenergic vasodilatation and thus reduced secondary stress on the heart, accompanied by beta-adrenergic cardiac stimulation, eventually brought about an altered circulatory situation which was, basically, comparable to circulation under conditions of physical stress, in cases of physical stress, particular attention should be given to polyfactorially caused cardiovascular transformation, contrary to the beta-adrenergic stimulation by isoprenaline. ECG variations likely to occur along with change from maximum to supramaximum isoprenaline doses are described and discussed. The TQ segment was shortened first by approximation of the T and P waves and resulting disappearance of the TP segment. The PQ segment was further shortened by increase of dosage. Further ST reduction then was recordable within the constantly shortened QT time. The T wave was flattened and widened, and the R wave went up.
以250微克/千克的最大异丙肾上腺素剂量诱发牛的平均心率为每分钟166次。心率间期PP如此显著缩短的同时，所有其他心电图段，如PQ、ST和TP，以及QRS波时间（初始心室变化）也都有高度显著的缩短。将合成拟交感神经药异丙肾上腺素与肾上腺素和去甲肾上腺素对牛心率和心电图作用的已知结果进行了比较，发现它能引起更强的心脏活动加速，心电图段缩短更明显。发现去甲肾上腺素、肾上腺素和异丙肾上腺素这三种儿茶酚胺之间的这种差异可归因于α-肾上腺素能受体和β-肾上腺素能受体刺激的差异。异丙肾上腺素不产生任何α-肾上腺素能效应，因此纯粹的β-肾上腺素能血管舒张从而减轻了心脏的继发性压力，同时伴有β-肾上腺素能心脏刺激，最终导致循环状况改变，基本上与身体应激条件下的循环相当，在身体应激情况下，应特别注意多因素导致的心血管变化，这与异丙肾上腺素的β-肾上腺素能刺激相反。描述并讨论了随着异丙肾上腺素剂量从最大剂量变为超最大剂量可能出现的心电图变化。TQ段首先因T波和P波接近以及TP段消失而缩短。PQ段随着剂量增加进一步缩短。然后在持续缩短的QT时间内可记录到ST段进一步降低。T波变平变宽，R波升高。
