Enkephalin and presynaptic inhibition in mammalian sympathetic ganglia

Presynaptic actions of 4-aminopyridine and gamma-aminobutyric acid on rat sympathetic ganglia in vitro.

Responses to bath-applications of 4-aminopyridine(4-AP) and gamma-aminobutyric acid (GABA) were recorded intracellularly from neurones in the rat isolated superior cervical ganglion. 4-aminopyridine (0.1-1.0 mmol/l) usually induced spontaneous action potentials and excitatory postsynaptic potentials (EPSPs), which were blocked by hexamethonium. Membrane potential was unchanged; spike duration w...

Selective action of anesthetics on synapses and axons in mammalian sympathetic ganglia.

ANESTHETIC SUBSTANCES, in suitable concentrations, depress certain functions of the central nervous system, while leaving relatively unimpaired the capacity for activity in sensory nerve endings, peripheral nerve fibers, and various effector organs. In order to explain this selective action on the central nervous system it is usually assumed that synaptic mechanisms are more readily modified by...

Contrasting effects of presynaptic alpha2-adrenergic autoinhibition and pharmacologic augmentation of presynaptic inhibition on sympathetic heart rate control.

Presynaptic alpha2-adrenergic receptors are known to exert feedback inhibition on norepinephrine release from the sympathetic nerve terminals. To elucidate the dynamic characteristics of the inhibition, we stimulated the right cardiac sympathetic nerve according to a binary white noise signal while measuring heart rate (HR) in anesthetized rabbits (n = 6). We estimated the transfer function fro...

Contrasting effects of presynaptic 2-adrenergic autoinhibition and pharmacologic augmentation of presynaptic inhibition on sympathetic heart rate control

Tadayoshi Miyamoto, Toru Kawada, Yusuke Yanagiya, Tsuyoshi Akiyama, Atsunori Kamiya, Masaki Mizuno, Hiroshi Takaki, Kenji Sunagawa, and Masaru Sugimachi Department of Physical Therapy, Faculty of Health Sciences, Morinomiya University of Medical Sciences; and Department of Cardiovascular Dynamics, Advanced Medical Engineering Center, and Department of Cardiac Physiology, National Cardiovascular...

Modulation of Synaptic Amplification in Sympathetic Ganglia