CEREBRAL BLOOD FLOW AND pH IN EXCESSIVE CORTICAL DISCHARGE INDUCED BY METRAZOL AND ELECTRICAL STIMULATION

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Abstract
The local pH of the post. sigmoid gyrus in the cat was recorded by the Nims glass electrode method modified by Jasper and Cipriani [see B. A. 14(6): entry 10045] simultaneously with local cerebral blood flow with a heated thermocouple and local electrical activity from wick electrodes. Excessive cortical discharge as observed in the electro-corticogram induced by intraven. inj. of metrazol or by electrical stimulation of the contralateral cortex was followed immediately by a decrease in local cortical pH, then by an increase in local blood flow which if sufficient would cause a relative increase in pH. Increase in blood flow secondary to a rise in blood pressure following adrenalin inj. also produced an increase in cortical pH with little change in the electro-corticogram. The onset, intensity, duration, and form of the metrazol discharge were not appreciable affected by variations in cortical pH between 7.0 and 7.5 induced by hyperventilation, CO2 breathing, and by injection of acid or alkaline solns. into the blood stream. Local application of strychnine or metrazol produced a marked facilitation of cortical discharge without affecting the local pH of the cortex. With prolonged excessive discharge of the cortex the pH finally drops to values below 7.0 in spite of increased blood flow. Local cortical pH is evidently not an important factor in the detn. of the states of cortical facilitation.

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