Morphological changes accompanying physiological changes in atrial stretch receptors.

A shunt connecting the descending aorta and posterior vena cava was established surgically in six mongrel dogs. All animals subsequently developed hemodynamic and clinical signs of congestive heart failure at which time the shunt was closed. Six to seven weeks after ligation of the shunt, activity of the left atrial stretch receptors was recorded and found to be similar to that of sham-operated dogs. Methylene blue-stained sections of left atrial endocardium indicated that approximately one-third of the receptors were normal in histological appearance. The remaining two-thirds were fragmented and degenerate. Evidence is presented which indicates that structural changes in these receptors parallel their changes in physiological activity.