pH modulates the vestibular afferent discharge and its response to excitatory amino acids.
In the isolated inner ear of the axolotl (Ambystoma tigrinum) acid pH decreased and basic pH increased the resting and mechanically evoked spike discharge of semicircular canal afferent neurons. Variations in pH also modified the afferent neuron response to N-methyl-D-aspartic acid (NMDA) acid and to (+/-)-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA). Responses to both excitatory amino acid agonists increased at pH 7.8 (41% and 22%, respectively) and decreased by perfusion of the preparation with a saline solution, of pH 7.0 (28% in both cases). These results indicate that vestibular endorgans have a significant sensitivity to pH that could play a significant role in various pathological states, and may also contribute to the post-transductional processing of sensory information.
Vega
Rosario
R
Instituto de Fisiología, BUAP, Universidad Autónoma de Puebla, Apartado Postal 406, Puebla, Pue. 72000, México. axolotl@siu.buap.mx
Mercado
Francisco
F
Chávez
Hortencia
H
Limón
Agenor
A
Almanza
Angélica
A
Ortega
Aída
A
Pérez
Maria Eugenia
ME
Soto
Enrique
E
D000557:Ambystoma; D000818:Animals; D015214:Antigens, Differentiation, Myelomonocytic / Q000494:pharmacology; D018846:Excitatory Amino Acids / Q000494:pharmacology*; D005110:Extracellular Space / Q000502:physiology; D006863:Hydrogen-Ion Concentration / Q000187:drug effects*; D007814:Larva / Q000187:drug effects / Q000502:physiology; D009475:Neurons, Afferent / Q000187:drug effects* / Q000502:physiology; D012665:Semicircular Canals / Q000187:drug effects*; D013997:Time Factors; D014157:Transcription Factors / Q000494:pharmacology; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000494:pharmacology
D015214:Antigens, Differentiation, Myelomonocytic; D018846:Excitatory Amino Acids; C075373:MNDA protein, human; D014157:Transcription Factors; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid