Combined acute hypoxemia and hypercapnic acidosis increases atrial natriuretic polypeptide in conscious dogs.

To evaluate the changes in atrial natriuretic polypeptide during acute hypoxemia and acute hypercapnic acidosis, conscious mongrel dogs with controlled sodium intake were evaluated in four protocols: (1) 80 min of acute hypoxemia (PaO 2 =34±1 mm Hg) followed by 40 min of combined hypoxemia and hypercapnic acidosis (PaO 2 =38±1 mm Hg, PaCO 2 =60±3 mm Hg, pH=7.15±0.03) (n=7); (2) 40 min of combined acute hypoxemia and hypercapnic acidosis (PaO 2 =36±1 mm Hg, PaCO 2 =56±2 mm Hg, pH=7.20±0.03) induced immediately following control measurements (n=5); (3) 120 min of acute hypercapnic acidosis (PaCO 2 =58±1 mm Hg, pH=7.20±0.01) (n=5), and (4) 120 min of normoxemia and normocapnia (n=7)