Atrial natriuretic factor prohormone peptides are present in a variety of tissues

Utilizing two sensitive and specific radioimmunoassays which immunologically recognize 1) the 98 amino acid (a.a.) N-terminus and 2) the 28 a.a. C-terminus (i.e., a.a. 99-126) of the 126 a.a. atrial natriuretic (ANF) prohormone, various tissues including aorta, kidney, small intestine, colon, liver, spleen, lung, and testis were investigated to determine if the ANF prohormone was present in any of these tissues in addition to its previously demonstrated presence in heart and brain. Aorta with 62.3 +/- 3 ng of the N-terminus/g of tissue and 51.6 +/- 1.8 ng of the C-terminus of the ANF prohormone/g of tissue had the highest concentration of the ANF prohormone of the previously undescribed ANF prohormone-containing tissues. The next highest concentration of the ANF prohormone was in the intestine, followed by lung and spleen. Pancreas, liver and kidney had similar levels of immunologically recognized ANF prohormone (approximately 1/50 of the aorta), while the testis and cerebrum had low levels. These results suggest that a much larger variety of tissues synthesize and/or store the ANF prohormone than is presently thought.