Extracellular H+ iontophoresis modifies responses to gamma-aminobutyric acid and cyanide of reticulospinal vasomotor neurons in rats.
Responses of reticulospinal vasomotor neurons, recorded in the rostral ventrolateral reticular nucleus of the medulla oblongata, to gamma-aminobutyric acid (GABA) and cyanide microiontophoreses were examined during H+ iontophoresis in anesthetized rats. Extracellular H+ iontophoresis attenuated GABA-evoked decreases and enhanced cyanide-induced increases in the neuronal activity, but had no effect on the neuronal activity when applied alone. Opposite responses were produced during OH- iontophoresis. Similar effects were also observed on the glycine-evoked inhibition of these neurons during H+ and OH- iontophoreses, suggesting that H+ modulation of the GABA-evoked inhibition may not result from a specific action at the GABA receptor-channel complex. It is concluded that extracellular H+ ions exert a modulatory action on responses of the reticulospinal vasomotor neurons to other neuro-active substances and may significantly contribute to hypoxic-ischemic cardiovascular regulation.
Department of Neurology and Neuroscience, Cornell University Medical College, New York, NY 10021.
M K
MK
Sun
D J
DJ
Reis
D000818:Animals; D003486:Cyanides / Q000494:pharmacology*; D004347:Drug Interactions; D004558:Electric Stimulation; D007478:Iontophoresis; D008297:Male; D008526:Medulla Oblongata / Q000187:drug effects; D009474:Neurons / Q000187:drug effects*; D011522:Protons; D051381:Rats; D017207:Rats, Sprague-Dawley; D014666:Vasomotor System / Q000187:drug effects; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
D003486:Cyanides; D011522:Protons; D005680:gamma-Aminobutyric Acid