Effect of increased concentrations of ca++ and mg++ in the fluid perfusing the cerebral ventricles, and hypoxia on evoked tongue jerks.

Effect of increased concentrations of Ca++ and Mg++ in the fluid perfusing the cerebral ventricles, and hypoxia on evoked tongue jerks. Acta Physiol. Pol., 1978, 29 (1): 27-36. The infraorbital nerve, the sensory part of the trigeminal nerve, was stimulated in rats under chloralose anaesthesia. Electric stimuli of 0.2 Hz caused retractive movements of the stretched tongue. These evoked tongue jerks (ETJ) were recorded directly on a kymograph or on a linear recorder. Using a stereotaxic apparatus cannulas were inserted into both lateral ventricles of the brain for infusion of McIlwain-Rodnight's fluid at a rate of about 50 microliter/minute. The cannula for outflow of the perfusing fluid was inserted into the cerebellomedullary cistern. The ETJ was enhanced by 43%, on the average, during perfusion of the cerebral ventricles with solutions with fivefold increased concentration of calcium ions, and decreased by a mean value 24% when the perfusing solution contained a higher concentration of magnesium ions. After 10 min of breathing with increased respiratory dead space, which caused hypoxia and hypercapnia, the amplitude of ETJ diminished by 65%, on the average.