Table 2.

Average peak responses of capsaicin-sensitive vagal lung afferent fibres to intravenous injection of three receptor agonists before and after various antagonist pretreatments

Receptor agonist	Pretreatment	Control (impulses s−1)	After pretreatment (impulses s−1)
Capsaicin	CPZ	8.14 ± 1.31	0.19 ± 0.13*
Capsaicin	CPZ +iso-PPADS	7.74 ± 1.38	0.22 ± 0.13*
Capsaicin	Vehicles of CPZ +iso-PPADS	7.52 ± 1.10	7.61 ± 1.41
α,β-meATP	iso-PPADS	8.82 ± 2.39	0.24 ± 0.24*
α,β-meATP	CPZ +iso-PPADS	10.83 ± 2.52	0.98 ± 0.76*
Phenylbiguanide	CPZ +iso-PPADS	11.79 ± 1.99	10.70 ± 1.82

Baseline values are data averaged over 30 s, whereas peak values are data averaged over 3 s.

^*Significantly different from response before pretreatment (control). Data in each group are the mean ± s.e.m. of eight fibres from eight rats. α,β-meATP, α,β-methylene-ATP; CPZ, capsazepine; iso-PPADS, iso-pyridoxalphosphate-6-azophenyl-2′,5′-disulphonate; CPZ +iso-PPADS, a combination of CPZ and iso-PPADS; vehicles of CPZ +iso-PPADS, a combination of vehicles of CPZ and iso-PPADS.