Figure 3. Suramin (A; 100 pmol) and PPADS (B;10 pmol) antagonism of P2 receptors in the NTS attenuate the peripheral chemoreceptor reflex bradycardia selectively.

The effect of blocking P2 receptors in the NTS was selective for the chemoreceptor reflex circuit mediating the bradycardia (n = 6) since responses following pharyngo-oesophageal afferent activation were unperturbed (n = 6). ▪, stimulation of peripheral chemoreceptors; □, pharyngo-oesophageal distension.