Importance of noradrenergic structures of cerebellar fastigial nucleus in control of breathing in rats

Objective. The aim of the study is to examine the influence of noradrenergic structures of cerebellar fas-tigial nucleus (CFN) on the regulation of various parameters of breathing patterns and bioelectric activity of inspiratory muscles. Materials and Methods. Experiments were conducted on 22 spontaneously breathing adult rats under urethane anesthesia. In the first set of experiments the authors analyzed respiratory response and bioelectrical activity of the diaphragm and external intercostal muscles to the microinjection of noradrenaline solutions of various concentrations in CFN. The measurements were conducted with pneumotachography and electromyography. During the second set of experiments electric simulation of CFN by impulse current was carried out. The current varied in frequency and strength before and during activation of noradrenergic structures of the nucleus. Results. The main effect of activation of CFN noradrenergic structures is an increase in respiratory rate and minute pulmonary ventilation. These changes correspond to electromyogram (EMG) parameters of inspiratory muscles. Preliminary local administration of noradrenaline into CFN provides empowerment of nuclei influence on respiration and activity of inspiratory muscles in response to electrical stimulation. Conclusion. Peculiarities of CFN modulating effects on respiration are determined by functional state of its noradrenergic structures.