Purine compounds (ATP, adenosine 5'-diphosphate (ADP), adenosine 5'-monophosphate (AMP) and adenosine; 3-6 μmol kg-1 and capsaicin (10 μg kg-1) were given as a rapid bolus into the right atrium (5 ml test solution+5 ml physiological saline flush) or the right pulmonary artery (1 ml test solution+3 ml physiological saline flush). When given in the latter site, smaller doses were used, i.e. 0.5-3 μmol kg-1 for purine compounds and 1-5 μg kg-1 for capsaicin. α,β-Methylene ATP (α,β-mATP) and β,γ-methylene ATP (β,γ-mATP) were give as one low dose only (0.75 μmol kg-1) to avoid systemic side effects. Volume controls consisted of either 5+5 ml or 1+3 ml physiological saline. All injections were performed in the same mode by the same person. To exclude involvement of baroreceptors in the recorded neural activity, the latter was monitored before and after a bolus of nitroglycerine (1mg, I.V.; n=5). The effect of ganglionic transmission blockade on the effects of ATP and capsaicin was determined by the administration of hexamethonium (10 mg kg-1, I.V.; n=7).
