The inhibitory influence of the bulbar reticular formation and its influence on the spinal cord
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Experiments were performed on intact cats. The authors studied the changes of the effects of direct electrical stimulation of mesencephalic facilitatory and of bulbar inhibitory areas on the rhythmic reflex of antagonists associated with development of ether and chloralose anesthesia.
Experiments demonstrated that distinct generalized inhibition of antagonists, which is observed in condition of ether anesthesia, disappears in 1.5–2 hours after the interruption of anesthesia. At this time the facilitatory effect which is frequently associated with a tonic contraction is still pronounced. If the anesthesia is deepened gradually or at once (by intravenous injection of chloralose) the generalized inhibition of the reflex quivering is again manifested to its full extent after the administration of 15–20 mg/kg of body weight. At the same time the facilitatory effect of the mesencephalic reticular formation is greatly weakened. The inhibitory effect of the bulbar reticular formation appeared to be more resistant to anesthesia: it weakens and disappears only with the large concentrations of the drug (50–60 mg/kg and more).
All this points to the following: 1) the mesencephalic facilitatory and the bulbar inhibiting areas possess different sensitivity and resistance to anesthetics, 2) the inhibitory effect of the reticular formation of the brain stem in nonanesthetized animals is obscured by its more significant facilitating effect on the spinal cord.
KeywordsSpinal Cord Electrical Stimulation Intravenous Injection Brain Stem Large Concentration
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