A means of metabolic investigation of small portions of the central nervous system in an active state

Abstract

Apparatus has been devised so that fluctuating potential gradients can be applied to portions of tissues of between 0.2 and 100 mg. in wt., while these are floating freely in oxygenated nutrient salines. Condenser pulses, of time constant about 0.5 msec., could be applied in this apparatus from condensers of about 4[mu] F. without causing any changes which might be mistaken for metabolic ones. A max. potential gradient of about 20 V./cm. was found to alter the metabolism of pieces of cerebral cortex which were floating in the apparatus in a balanced glucose saline. Respiration increased to up to 200% of its initial rate and lactic acid formation to some 300%. Similar increases were shown with cerebellar tissues and fragments from the basal ganglia and brain stem. The increases were partly inhibited by concns. of atropine which had very little, if any, effect on the levels of respiration and glycolysis normal for the tissues.