Abstract
The potentiating effect of disodium 2-methyl mercapto-5'-inosinate (Mes-IMP) on gustatory responses to monosodium glutamate (MSG) was examined and compared with those of sodium 5'-inosinate (5'-IMP) and sodium 5'-guanylate (5'-GMP) by recording responses in the whole chorda tympani nerve and in single gustatory fibers in rats. Mes-IMP had a lower threshold for response than 5'-IMP. Addition of 0.0001% Mes-IMP to 0.3% MSG yielded significant enhancement in the response. The enhancement produced by Mes-IMP was nearly equal to that shown by 5'-IMP of an amount ten times greater. The enhancement was predominantly observed in fibers responsive to sucrose. The magnitude of the enhancement, produced by the addition of a fixed amount of Mes-IMP to MSG of varying concentrations, was greater at MSG concentrations below 0.03 M than at higher concentrations.
