Figure 6. Intravenous injection of saline was without effect on chorda tympani nerve responses.

Sample neural responses to 0.5 M NaCl, 0.03 M Quinine, 1.0 M sucrose, or 0.01 N HCl before and after a single bolus injection (300 µM) of saline are illustrated (upper left). Data are summarized in the histogram (upper right). On the other hand, intravenous injection of ATP produced transient neural responses which could be blocked by prior injection of the purinergic antagonist PPADS (lower left). Intravenously administered PPADS was also effective in blocking lingually applied tastant responses. Data summarizing the antagonistic effect of PPADS on ATP injection or tastant lingual stimulation are illustrated (histograms middle and lower right, respectively).