1992 Volume 4 Issue 2 Pages 169-178
Alteration of subcellular localization of atrial granules (AGs) and changes in serum level of α-human ANP (α-hANP) were studied in twenty patients with various heart diseases by right atrial biopsies and sampling blood from several intracardiac sites before and after atrial pacing at a rate of 150/min for 20 min. After atrial pacing the mean right atrial pressure (RAP) was significantly increased from 4±2 mmHg to 6±2 mmHg (p<0.01) and pulmonary wedge pressure (PCWP) was also significantly increased from 8±3 mmHg to 14±5 mmHg (p<0.01) . The serum level of α-hANP in the right atrium (RA) was surprisingly increased from 64±35 to 295±119 pg/ml (p<0.01) after RA-pacing. The response to higher atrial pressures due to pacing caused tremendous secretion of α-hANP. The normal value of α-hANP level in the peripheral vein in the present study was 27±11 pg/ml. Electron dense AGs with diameters of 0.3 to 0.4 μm were abundant in atrial myocytes in the perinuclear area, especially in the Golgi area before atrial pacing. There were a few in the intermyofibrillar area, but they were scarce in the subsarcolemmal area, which suggested that the granules were produced in the Golgi apparatus. All AGs were confirmed to contain α-hANP. In this study the regulation of ANP in response to atrial pacing was elucidated by determining serum concentration of ANP in various cardiovascular sites and ultrastructural alteration of the distribution of atrial granules that contained α-hANP identified by immunocytochemistry. This study was performed in the complete absence of heart failure, and there were scarcely any disease specificities, or biased responses of the distribution of AGs in the atria to pacing.
