Abnormal Brain Permeability in CO2 Narcosis

Abstract

Introduction Carbon dioxide narcosis is a recognized phenomenon of the laboratory and in neurological practice.¹ Hypercapnia is known to produce changes in the EEG,² to dilate cerebral blood vessels,³ and to increase cerebral blood flow.⁴ The effect of hypercapnia on brain metabolism and permeability has been less intensively studied. In this report we have studied the effects of CO₂ on brain permeability using sodium S³⁵ sulfate and C¹⁴ urea as indicators, employing the methodologies of regional radioassay and autoradiography. Methods S³⁵ sodium sulfate (Abbott Laboratories, Chicago, "carrier free") was administered intravenously to cats in the following dosage: 1 or 2 mc/kg for animals sacrificed after 5 min and 0.5 or 1 mc/kg for animals sacrificed after 1 and 6 hr. The differing dosage of radioactivity did not affect the results, but the higher radioactive dose was more satisfactory for metabolite separation. The