Figure 7. Selective modulation by suramin of the peripheral chemoreceptor input but not the excitatory synaptic response from pharyngo-oesophageal receptors (PO) to NTS neurones.

Seven neurones responded to CN stimulation of chemoreceptors, of which five received synaptic input from PO receptors also. The former but not the latter inputs were attenuated by suramin as measured from the peak frequency of the evoked firing response and the total number of action potentials elicited above the basal discharge rate. Effects had partly reversed after a 10–15 min washout period. ▪, stimulation of peripheral chemoreceptors; □, stimulation of receptors at the pharyngo-oesophageal junction.