Membrane potentials in isolated neurones in vitro from Deiters' nucleus of rabbit

Abstract

The biochemical properties of isolated neurones of Deiters' nucleus of rabbit have been the subject of considerable study (for review, see Hyden, 1961), but their physiological status has not been investigated. In the present study, the ability of the isolated neurones of Deiters' nucleus to maintain resting potentials at 23°C has been demonstrated, and the effect of hypoxia, different medium glucose, potassium and sodium concentrations, and a ganglioside preparation has been examined. The latter agent was tested as it had been found to increase the membrane potential of cells in guinea-pig cerebral slices in vitro (Hillman, 1961). METHODS ApparatusA chamber was designed which would fit on a microscope stage, and allow the microelectrode to be in the same atmosphere as the cells; in this closed system, the cells could be subjected to a high concentration of oxygen, and could be viewed through the glass top of the chamber. The volume of the incubating medium was 300-400,u1. A drawing of the chamber is shown in Fig. 1. RecordingThe membrane potentials were recorded with micro-electrodes of tip diameter less than 11,, and resistances between 5 and 15 MQ2. These were attached to a non-polarizable electrode, connected to a Bak amplifier, and a Tektronix 502 oscilloscope. The electrode was mounted on a de Fonbrune micromanipulator, and the cells viewed through a Zeiss stereomicroscope II, 1958 model. They were usually penetrated under a magnification of 100 times. MediaFor more than a year attempts were made to record membrane potentials at 23 and 370 C in the Krebs-Ringer bicarbonate-glucose saline, of the same composition as had been used for studying guinea-pig cerebral slices in itro (Li & McIlwain, 1957; Hillman & Mcllwain, 1961). However, in this medium only 20-30 mV potentials could be recorded from the cells (Table 2, column 2).Therefore many variations in the K+, Na+, buffer, and glucose were tried. A solution containing the following constituents as final concentrations (mM) was finally adopted, because at room temperature it permitted mean membrane potentials of 39 mV, which could be significantly and reversibly altered (Table 1): NaCl 84, KCI 5, KH2PO4 1-24, MgSO4 1-3, CaCl2 2-8, NaHCO3 26 and glucose 50, equilibrated for at least 10 min with 95 % *Present address, Institute of Neurology, Queen Square, London.

A Calcium-Dependent Mechanism for Synapse and Nerve Cell Membrane Modulation

“…The dendrites break off when they are < 1 jum in diameter. The defects close and such nerve cells retain membrane potentials of 40-70 mV, phosphorylate, and respire (16,17). Thus, large antibody molecules cannot pass into such cells.…”