EFFECTS OF 2 WATER-SOLUBLE CONTRAST-MEDIA, MEGLUMINE IOTHALAMATE (CONRAY) AND MEGLUMINE IOCARMATE (DIMER-X), ON THE ELECTRIC-ACTIVITY OF IDENTIFIABLE GIANT-NEURONS OF AFRICAN GIANT SNAIL (ACHATINA-FULICA FERUSSAC)

Abstract

The influences of 2 water soluble contrast media, meglumine iothalamate and meglumine iocarmate, on neuronal excitability and neuronal sensitivity to putative transmitters were examined in comparison with those of sucrose using 2 identifiable giant neurons of A. fulica Ferussac (the TAN [tonically autoactive neuron] and the PON [periodically oscillating neuron]). A relatively low increase of osmotic pressure of the extracellular fluid, produced by the application of contrast media, reversed the Cl- dependent inhibition caused by a putative transmitter. The same increase of this osmotic pressure did not influence the Cl- independent inhibition and the excitation of the neuron examined. The hyperpolarization of neuromembrane was caused by an increase of osmotic pressure of the extracellular fluid. Its relatively high increase was necessary to make spontaneous spike discharges disappear totally. All effects of the 2 contrast media observed in this study were due to the increase of osmotic pressure of the extracellular fluid; no specific effect of the contrast media containing the I on the indicators used was observed.