Analysis of the central vasomotor effects of (−)-N-(1-phenylethyl)guanidine, a new adrenergic neuron blocking agent

1969 ◽  
Vol 47 (8) ◽  
pp. 725-729 ◽  
Author(s):  
S. K. Bapat ◽  
B. N. Dhawan ◽  
R. C. Srimal
Keyword(s):  
Pressor Response ◽  
Intrathecal Injection ◽  
Blocking Agent ◽  
Peak Effect ◽  
Nictitating Membrane ◽  
Adrenergic Neuron ◽  
Vasomotor Center ◽  
Spinal Compression ◽  
Nictitating Membrane Response ◽  
Stimulation Of

Central vasomotor effects of (−)-N-(1-phenylethyl)guanidine, a potent adrenergic neuron blocking agent, were studied. The compound was localized in the central sites by intracerebroventricular injection, topical application on the vasomotor center, intra-arterial (vertebral) injection, and intrathecal injection. It potentiated the carotid occlusion response, response to anoxia, spinal compression vasomotor response, and the threshold and optimal vasomotor responses to direct electrical stimulation of the medullary vasomotor center without affecting the peripheral norepinephrine pressor response and the nictitating membrane response. The peak effect was obtained in 15–20 min, and recovery occurred in 80–90 min. The compound probably made catecholamines unavailable to the vasomotor neurons, making them more excitable.

scholarly journals Effects of peripheral and spinal κ-opioid receptor stimulation on the exercise pressor reflex in decerebrate rats

2014 ◽  
Vol 307 (3) ◽  
pp. R281-R289 ◽  
Author(s):  
Steven W. Copp ◽  
Audrey J. Stone ◽  
Katsuya Yamauchi ◽  
Marc P. Kaufman
Keyword(s):  
Opioid Receptor ◽  
Opioid Receptors ◽  
Pressor Response ◽  
Intrathecal Injection ◽  
Muscle Afferents ◽  
Femoral Arteries ◽  
Exercise Pressor Reflex ◽  
Pressor Responses ◽  
Pressor Reflex ◽  
Stimulation Of

The exercise pressor reflex is greater in rats with ligated femoral arteries than it is in rats with freely perfused femoral arteries. The exaggerated reflex in rats with ligated arteries is attenuated by stimulation of μ-opioid and δ-opioid receptors on the peripheral endings of thin-fiber muscle afferents. The effect of stimulation of κ-opioid receptors on the exercise pressor reflex is unknown. We tested the hypothesis that stimulation of κ-opioid receptors attenuates the exercise pressor reflex in rats with ligated, but not freely perfused, femoral arteries. The pressor responses to static contraction were compared before and after femoral arterial or intrathecal injection of the κ-opioid receptor agonist U62066 (1, 10, and 100 μg). Femoral arterial injection of U62066 did not attenuate the pressor responses to contraction in either group of rats. Likewise, intrathecal injection of U62066 did not attenuate the pressor response to contraction in rats with freely perfused femoral arteries. In contrast, intrathecal injection of 10 and 100 μg of U62066 attenuated the pressor response to contraction in rats with ligated femoral arteries, an effect that was blocked by prior intrathecal injection of the κ-opioid receptor antagonist nor-binaltorphimine. In rats with ligated femoral arteries, the pressor response to stimulation of peripheral chemoreceptors by sodium cyanide was not changed by intrathecal U62066 injections, indicating that these injections had no direct effect on the sympathetic outflow. We conclude that stimulation of spinal, but not peripheral, κ-opioid receptors attenuates the exaggerated exercise pressor reflex in rats with ligated femoral arteries.

Single-unit analysis of different hippocampal cell types during classical conditioning of rabbit nictitating membrane response

1983 ◽  
Vol 50 (5) ◽  
pp. 1197-1219 ◽  
Author(s):  
T. W. Berger ◽  
P. C. Rinaldi ◽  
D. J. Weisz ◽  
R. F. Thompson
Keyword(s):  
Classical Conditioning ◽  
Pyramidal Cell ◽  
Action Potentials ◽  
Pyramidal Cells ◽  
Cell Types ◽  
Firing Frequency ◽  
Spontaneous Firing ◽  
Nictitating Membrane ◽  
Nictitating Membrane Response ◽  
Firing Characteristics

Extracellular single-unit recordings from neurons in the CA1 and CA3 regions of the dorsal hippocampus were monitored during classical conditioning of the rabbit nictitating membrane response. Neurons were classified as different cell types using response to fornix stimulation (i.e., antidromic or orthodromic activation) and spontaneous firing characteristics as criteria. Results showed that hippocampal pyramidal neurons exhibit learning-related neural plasticity that develops gradually over the course of classical conditioning. The learning-dependent pyramidal cell response is characterized by an increase in frequency of firing within conditioning trials and a within-trial pattern of discharge that correlates strongly with amplitude-time course of the behavioral response. In contrast, pyramidal cell activity recorded from control animals given unpaired presentations of the conditioned and unconditioned stimulus (CS and UCS) does not show enhanced discharge rates with repeated stimulation. Previous studies of hippocampal cellular electrophysiology have described what has been termed a theta-cell (19-21, 45), the activity of which correlates with slow-wave theta rhythm generated in the hippocampus. Neurons classified as theta-cells in the present study exhibit responses during conditioning that are distinctly different than pyramidal cells. theta-Cells respond during paired conditioning trials with a rhythmic bursting; the between-burst interval occurs at or near 8 Hz. In addition, two different types of theta-cells were distinguishable. One type of theta-cell increases firing frequency above pretrial levels while displaying the theta bursting pattern. The other type decreases firing frequency below pretrial rates while showing a theta-locked discharge. In addition to pyramidal and theta-neurons, several other cell types recorded in or near the pyramidal cell layer could be distinguished. One cell type was distinctive in that it could be activated with a short, invariant latency following fornix stimulation, but spontaneous action potentials of such neurons could not be collided with fornix shock-induced action potentials. These neurons exhibit a different profile of spontaneous firing characteristics than those of antidromically identified pyramidal cells. Nevertheless, neurons in this noncollidable category display the same learning-dependent response as pyramidal cells. It is suggested that the noncollidable neurons represent a subpopulation of pyramidal cells that do not project an axon via the fornix but project, instead, to other limbic cortical regions.(ABSTRACT TRUNCATED AT 400 WORDS)

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