Immunoreactive forms of atrial natriuretic peptide in rabbit atrial heart tissue

A variety of biologically active atrial natriuretic peptides (ANPs) exist. In the present paper a study of the molecular heterogeneity of rabbit ANP is reported. Fractions from Sephadex G-50 chromatography of atria acetic acid extracts were assayed for their immunological and natriuretic activities. Correlation between the two activities was found not to be linear, nevertheless a fraction was shown to contain the highest quantity of immunoreactive hormone and to be also responsible for the major natriuretic response. Gel electrophoresis analysis of this fraction followed by immunoblotting with anti-ANP serum, showed the presence of three immunoreactive bands of different molecular weight (3,400-6,500; 16,000; 30,000 daltons), probably corresponding to different forms of the hormone.