Fumihide Yoshida

The Influence of Electrical Stimulation of Brain on Cardiac Function

Purpose: It is widely known that the various electrocardiographic changes are observed in the patients suffering from various cerebral diseases. However, there still remain many unknown facts about how and why such changes occur. In order to study the effects on cardiac function, especially on electrocardiogram, of the electrical stimulation of brain of dog, with special reference to thalamus and hypothalamus, the coronary blood flow and cardiac output as well as blood pressure as parameters of the cardiac function were measured. Materials and Methods: 24 adult mongrel dogs, weighing from 7 to 12 kilograms were employed in this study. The bipolar concentric needle electrodes were implanted in the aimed sites of the dog brain using stereotaxic instrument devised by the Institute of Brain Research, Faculty of Medicine, University of Tokyo. More than a week later, the muscle relaxant, Gallamine triethiodide was injected intravenously at the rate of 10 to 15mg per kilogram body weight. Then, without the use of an anesthetic and under the artificial positive pressure respiration, the chest of dog was opened. Fixing probes on the left circumflex branch of the coronary artery and the ascending aorta, the coronary blood flow and cardiac output were determined with rectangular wave electromagnetic flowmeter. Moreover, the blood pressure of femoral artery and the limb-lead electrocardiogram were recorded simultaneously for observation and study. The given sites were stimulated with rectangular pulse of 100 cps and 1-20V, for 10 to 30 seconds. In some cases, anesthetics, Chloralose and Gallamine triethiodide were used together simultaneously. The sites for stimulation were thalamus, epithalamus, hypothalamus, sub-thalamus, midbrain and other various sites, totaling 96 points, and the stimulation were given 137 times in all. Results: (I) 1) In the thalamus group, more than 20% rise of the blood pressure was seen in 53% of the cases. Especially, it was seen frequently in the midline and medial nuclei groups and in these groups the blood pressure rose significantly in the majority of the cases.