controlled sodium content diet (0.3 %) (for 42 days) then controlled sodium content diet (8 %) (for 42 days) then 10% CO2, 20% O2, 70% N2 (10 %) (for 0.4 hours) then ambient air (for 0.1 hours)

 controlled sodium content diet (0.3 %) (for 42 days) then controlled sodium content diet (8 %) (for 42 days) then atropine (1 mg/kg) then 10% CO2, 20% O2, 70% N2 (10 %) (for 0.1 hours)

 controlled sodium chloride content diet (0.3 %) (for 21 days) then controlled sodium chloride content diet (8 %) (for 42 days) then ambient air (between 0 and 0.1 hours)

 controlled sodium content diet (0.3 %) (for 42 days) then controlled sodium content diet (8 %) (for 42 days) then atropine (1 mg/kg) then ambient air (between 0 and 0.4 hours)

 controlled sodium content diet (0.3 %) (for 42 days) then controlled sodium content diet (8 %) (for 42 days) then atropine (1 mg/kg) then 10% CO2, 20% O2, 70% N2 (10 %) (for 0.4 hours) then ambient air (for 0.1 hours)

 controlled sodium chloride content diet (0.3 %) (for 21 days) then controlled sodium chloride content diet (8 %) (for 42 days) then 10% CO2, 20% O2, 70% N2 (10 %) (for 0.1 hours)