Inhibition by intravenously administered sodium bicarbonate of neuronal activity in medial vestibular nucleus neurons.
The effects of 7% sodium bicarbonate on medial vestibular nucleus (MVN) neurons were examined to elucidate the mechanism underlying its anti-vertigo action, using alpha-chloralose-anesthetized cats. Intravenous injection of the drug at 1, 2 and 4 ml/kg every 10 min dose-dependently inhibited rotation- and glutamate-induced firing of type 1 neurons, although a low dose of the drug enhanced firing in a few neurons. However, microiontophoretic application of bicarbonate ions did not inhibit rotation- or glutamate-induced firing. After injection of the drug, the Po2 level in arterial blood did not differ from previous levels, but the bicarbonate ion levels dose-dependently increased concomitantly with an increase in pH, as compared with previous levels. These results suggest that the intravenous injection of 7% sodium bicarbonate directly inhibits the neuronal activity of the MVN, although the lower dose may enhance neuronal activity by acting on the peripheral vestibule.
Kawabata
A
A
Department of Pharmacology, Faculty of Medicine, Kyoto University, Japan.
Kishimoto
T
T
Ujihara
H
H
Sasa
M
M
Takaori
S
S
D000818:Animals; D001639:Bicarbonates / Q000008:administration & dosage / Q000494:pharmacology*; D002415:Cats; D007275:Injections, Intravenous; D009433:Neural Inhibition; D012964:Sodium / Q000008:administration & dosage / Q000494:pharmacology*; D017693:Sodium Bicarbonate; D009435:Synaptic Transmission / Q000187:drug effects*; D014725:Vestibular Nerve / Q000187:drug effects*; D014726:Vestibular Nuclei / Q000187:drug effects
D001639:Bicarbonates; D017693:Sodium Bicarbonate; D012964:Sodium