This study analyzed by high performance gel permeation chromatography (HPGC) molecular forms of atrial natriuretic peptide (ANP) in plasma from anesthetized dogs stimulated by balloon inflation at the main pulmonary artery (Group A, n=4), right atrial pacing (Group B, n=4) and low-molecular dextran injection to right atrium (Group C, n=4), Mean pulmonary arterial (PA) pressure, mean right atrial (RA) pressure, mean arterial pressure, heart rate and ECG were monitored by polygraph system Mean PA pressure in Group A, heart rate in Group B and mean RA pressure in Group C increased significantly by the stimulation (p<0.01, p<0.001 and p<0.05 respectively). Other parameters were not changed significantly in the three groups. There were significant increases in ANP concentration after the three stimulations (Group A : 52.4±5.4 (SD) pg/ml→86.4±12.2 (SD) pg/ml, Group B e 43.8±6.7 (SD) pg/ml→72.0±14.1(SD) pg/ml, Group C : 42.7±8.8 (SD) pg/ml→69.3±10.0 (SD) pg/ml; each p<0.01). Gel filtration profiles showed that the increased form of plasma ANP in the three nrouos was α-ANP. These results suggest that α-ANP may be a main molecular form in plasma from dogs stimulated by the stretch of pulmonary arterial wall and right atrial wall, and atrial pacing.
