Abstract
When injected intravenously, morphine was shown by v. Egmond to cause cardiac arhythmia in dogs. Einthoven and Meek and Eyster studied the results of such injections electrocardiographically. Einthoven concluded that these were due to stimulation of the vagus centers. He found complete lack of uniformity in the results. Meek and Eyster believed the effects to be due to disturbances in conduction between sinus and auricle and between auricles and ventricles.
The similarity of some of Einthoven's curves to those resulting from faradic stimulation of the right vagus nerve and of others from stimulation of the left nerve rendered it probable that morphine sometimes had a preponderating influence on the right and at others on the left vagus nerve and center. Experiments were accordingly carried out in twelve dogs, in six of which the right and in six of which the left vagus nerves were removed aseptically. In 3 morphine was injected before operation. Registration was galvanometric. In three dogs (one right during three attempts and two left during two and three attempts) arhythmia characteristic of morphine poisoning was not obtained. 1 In three it was obtained on the first attempt, in five on the second and in one on the third. In five right vagus and in four left vagus dogs injection succeeded and the resulting arhythmias were directly comparable to those obtained on faradic stimulation. In the right vagus dogs the auricles, except for occasional contractions which escaped at long intervals, and also the ventricles ceased to beat. The circulation was carried on by ectopic ventricular contractions. That there was no defect in conduction was shown in a number of ways. In the left vagus dogs the auricles were merely slowed.
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