IS THERE A PERICARDIAL RESTRICTION TO THE CARDIAC SECRETION OF ATRIAL-NATRIURETIC-FACTOR

Atrial natriuretic factor (ANF) is secreted from atrial myocytes in re sponse to increased atrial wall stress caused by increased transmural pressure. This study investigates whether the presence of an intact pe ricardium restricts the ANF secretory response to an increment in left atrial pressure caused by acute aortic constriction in anaesthetized open-chest pigs. The rise in ANF plasma concentration secondary to con striction was higher when the pericardium had been surgically opened t han when it was left intact. Furthermore, an opened pericardium led to a larger increase during constriction in left atrial diameter as meas ured by sonomicrometry. The results suggest that the intact pericardiu m restricts the cardiac release of ANF secondary to aortic constrictio n, probably by restricting left atrial dilatation.