Tissue distribution of atrial natriuretic factor in normal and pathologic human hearts

The tissue distribution and possible neuroendocrine nature of atrial natriuretic factor (ANF) were studied, using the avidin-biotin-peroxidase technique and antibodies to ANF, chromogranin (Ch), and neuron-specific enolase (NSE). Tissues examined included: Group 1, formalin-fixed and fresh frozen atrial tissue from adjacent areas of the hearts from two heart-lung-transplant patients; Group 2, the entire atria and sampling of other areas from formalin-fixed hearts of five gunshot wound or automobile accident victims; and Group 3, formalin-fixed right auricular tissue from 19 open-heart-surgery patients. In each case of Group 3, the ANF score, expressed as the product of the percentage of stained areas by the staining intensity, was correlated with age, weight, height, blood pressure, ejection fraction, and degree of coronary arterial stenosis. It was found that: (a) ANF was limited to atrial myocytes; the staining was significantly stronger in the right atrium, diffuse and most intense in auricles and pectinate muscles, diffuse and strong in subendocardium, focal and weak in other areas; (b) although ANF has been reported to be a peptide hormone stored in dense-core granules, it does not seem to belong to the diffuse neuroendocrine system because Ch and NSE were consistently absent in cardiac myocytes; and (c) although the limited numbers of evaluable clinical parameters do not significantly correlate with ANF scores, a change in the pattern and intensity of ANF staining was noted in some cases of Group 3.