A. Van Harreveld

Brain electrolytes and cortical impedance.

A 50% glucose solution was administered intravenously to rabbits at a rate of about 1 cc/min until death of the preparation. An analysis of the brain showed that besides water the tissue had lost a considerable amount of its chloride and sodium (20–25%). The amount of potassium in the brain remained practically constant. The cortical impedance increased markedly during the glucose infusion. These findings support the thesis that the compartment of the tissue containing the bulk of the chloride and sodium ions has a special significance for the cortical impedance.

ACUTE ASPHYXIATION OF THE SPINAL CORD AND OF OTHER SECTIONS OF THE NERVOUS SYSTEM.

Oxygen lack causes an impedance increase of the spinal cord coinciding in time with an asphyxial potential which can be led off from the spinal gray matter against an indifferent electrode. After c...

Recovery of cerebral cortex from asphyxiation.

Cerebral asphyxiation causes, after a latency of 2–3 min, a marked increase in cortical impedance, a transport of chloride (probably accompanied by sodium) into apical dendrites and a swelling of these structures. The reversibility of these changes was investigated by reoxygenating the brain for 15 min after periods of asphyxiation ranging from 15 to 75 min. All the asphyxial changes were in part of the experiments completely reversed by reoxygenation after circulatory arrests up to 60 min in duration. The course of the impedance changes showed this active removal to occur during the first 5–10 min of reoxygenation. Even after asphyxiations of long duration electrolytes can thus be removed actively from cellular elements. In part of the experiments abnormal amounts of chloride were found after reoxygenation in the apical dendrites although the cortical impedance and the dendritic diameter had reverted to preasphyxial values, indicating that in these experiments sodium had been removed in combination with ...

Conductivity changes in some organs after circulatory arrest.

A loss of electrical conductivity after circulatory arrest was observed in the submaxillary salivary gland, liver, kidney, and skeletal muscle. A drop in conductivity of 85–90% of the original value developed in about 0.5 hr in the liver. In the kidney the loss was less severe. Salivary glands lost about 70–80% of their conductivity in 1.5 hr. The losses in muscle conductivity developed late and were not greater than 50%. The drop in conductivity observed in the various organs after circulatory arrest can be accounted for by losses of extracellular electrolytes from the tissues, which could be demonstrated in preparations stained for chloride. In this context the electrolytes in the blood plasma have to be included in the extracellular compartment. The extracellular electrolytes are lost either because they are transported into the intracellular compartment or because they leave the tissue with blood that flows out of the organ after circulatory arrest.

Cortical discontinuity and propagation of spreading depression.

The transmissibility of spreading depression across a cut severing all layers of the cortex was investigated in preparations in which 3 weeks to 3 months was allowed for healing of such an injury. ...

Electrical conductivity and electrolyte distribution in a secreting salivary gland

During the first 4–7 min of pilocarpine-induced secretion the submaxillary gland lost a large part of its electrical conductivity (a mean loss of 40% in 8 experiments). In preparations of control and experimental glands treated with a histochemical method for chloride a marked loss of fluid and electrolytes from the intertubular spaces could be demonstrated during this period. This loss of extracellular electrolytes provides an explanation for the drop in conductivity of the gland. A comparison of control and experimental glands showed that during the first minutes of secretion the gland lost water and total solids, decreased in potassium and chloride content, gained sodium, and increased slightly in total cation concentration.

Innervation and reinnervation of cricothyroid muscle in the rabbit.

The m. cricothyroideus of the rabbit is innervated by two motor nerves (n. laryngeus superior and n. laryngeus medius). No indication of extensive polyneuronal innervation was found in gold stained...