Cerebral Subsystems and Isolated Tissues

Abstract

Parts of the brain, as of other organs of the animal body, can be remarkably autonomous. Survival of much of their functioning for a few hours can require only a minimal supply of materials. When relevant investigations began in the author’s laboratory in the 1940s, this was readily accepted with respect to coldblooded animals such as frogs and small fish, of which the almost intact, isolated brain remained electrically active when supplied with simple bathing solutions. Comparable success was not obtained with preparations from mammalian cerebral systems. However, parts of the brain from laboratory animals and from man had been employed for many years as tissue slices in studying other aspects of cerebral functioning, especially respiration and metabolite interconversion. This was extended first to the metabolic maintenance in tissue slices of their content of labile materials including ATP and phosphocreatine and second to the metabolic maintenance of gradients in Na⁺ and K⁺ ions between the tissues and bathing solutions. It was then shown that application to the tissues of fluctuating electrical potentials caused changes in the tissue content of the substances just described.^1,2 The electrical stimuli led to breakdown of the labile compounds, to diminution of the concentration gradients, and to increase in the energy-yielding processes of respiration and glycolysis.