[Central mechanisms of the development of ischemic disorders of heart rhythm]

The activity of afferent and internuncial neurons of the bulbar cardiovascular centre (BCVC) was evaluated, using microelectrodes, in conditions of serotonin microinjections, altered blood gas composition and sensomotor cortical stimulation, in acute experiments in cats and rabbits. The afferent flow from ischemized myocardium was examined at the level of nodular-ganglion neurons. Cortical stimulation, changed blood O2 and CO2 proportions and the afferent message related to impaired coronary flow are shown to affect primarily the activity of internuncial BCVC neurons. Myocardial ischemia is shown to be much more frequently complicated by idioventricular arrhythmias, including ventricular fibrillations, under sensomotor cortical stimulation. Disintegrated operation of the afferent and internuncial BCVC neurons that precedes the development of severe ischemic arrhythmias may be due to a heavier afferent flow from heart receptors, descending influences from the cortical sensomotor area, and altered blood gas composition and a lower serotonin level in the medulla oblongata, associated with myocardial ischemia.