Fig. 22

Responses to 0.3 M sucrose (plotted upwards) in S fibers and to 0.002 M citric acid in the same S fibers (plotted downwards) expressed as the number of impulses/secs during the first 5 s of stimulation. The dotted line in the columns show the responses to the citric acid in the same S fibers after miraculin. The response to citric acid was significantly increased in fibers labelled with M. In an acidic environment miraculin stimulates the sweet receptors on TRCs, which then transmits impulses in their S fibers. These data resolved the riddle on how miraculin works and added support to labelled-line hypothesis. [1]