A simple method for the construction of a recording-injection microelectrode with glass-insulated microwire

A method to record changes in local neuronal discharge in response to infusion of small drug quantities in awake monkeys

A newly designed combination microelectrode-injection system is described which can be used to record electrophysiological responses of individual neurons in the primate brain to local administration of small quantities of drugs or other compounds. The assembly of the system is simple, and the materials used are inexpensive. The system consists of a standard tungsten microelectrode alongside fused silica tubing within a polyimide sleeve. The major advantage of this device is the ability to record with excellent quality, changes in the activity of single cells in vivo within 50-100 microm of the location of drug injections.

Frequency dependent sympathetic modulation of vasomotor tone in the anesthetized rat

The hypothesis that sympathetic nerve system modulates a specific frequency range of blood pressure fluctuation was tested by electrical stimulation of the medullary sympathetic excitatory sites in anesthetized, paralyzed, vagotomized, cardiac sympathetic blocked, baroreceptor transected and angiotensin II converting enzyme inhibited rats. The frequency tested ranged from 0.02 to 1.7 Hz. For blood pressure fluctuation within this range there was no specific sympathetic reactive zone. Instead, low frequency fluctuation of sympathetic flow produced blood pressure fluctuation of the same frequency. Transfer magnitude of renal sympathetic activity to blood pressure decrease logarithmically with the increase of stimulation frequency. The relationship between the sympathetic spectral power (P(SND), (microV.s)2/Hz) and the blood pressure spectral power (P(BP), mmHg2/Hz) was found as P(BP)=10(1.3) x P(SND) x 10(-4.7x(frequency)). This transfer function demonstrates that when blood pressure fluctuation is used to estimate the sympathetic activity, it should be frequency weighted.