Threshold determination of spreading depression evoking substances in the retina in vitro.
A technique for the determination of the threshold concentrations of chemical substances for elicitation of spreading depression is described. The technique minimizes the interference of mechanical stimulating effects and alterations in the susceptibility of the retina to spreading depression due to changes in unstirred layers at the liquid-tissue interphase. The following threshold concentrations were shown to elicit the wave: 8000-10000 microM KCl, 100-200 microM sodium glutamate, 5-10 microM sodium kainate, 10-20 microM sodium N-methyl-aspartate, 600-1200 microM (NH4)2SO4 and 400-600 microM BaCl2. Variations of K+ or Mg2+ concentration in the standard Ringer solution that may cause an increase or decrease of spreading depression velocity have an inverse effect on the threshold for elicitation of the reaction.
Martins-Ferreira
H
H
Departamento de Neurobiologia, Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brasil.
Ribeiro
L J
LJ
do-Carmo
R J
RJ
D000818:Animals; D002642:Chick Embryo; D013181:Cortical Spreading Depression / Q000187:drug effects*; D007552:Isotonic Solutions / Q000008:administration & dosage; D008452:Maximum Allowable Concentration; D012160:Retina / Q000502:physiology*; D000077331:Ringer's Solution; D013997:Time Factors
D007552:Isotonic Solutions; D000077331:Ringer's Solution