ANF BINDING-SITES IN THE HEART OF THE QUAIL (COTURNIX-COTURNIX-JAPONICA)

The distribution pattern of rat [I-125]-atrial natriuretic factor (ANF ) binding sites in the cardiac regions of the Japanese quail was exami ned by in vitro quantitative autoradiography. Elevated ANF binding den sities (519 +/-121 fmol/mg protein) were found in the posterior vena c ava, while lower binding levels (between 40 and 50 fmol/mg protein) we re found in sinus venosus, aortic bulb, and endomural vessels, with th e ventricular wall having the lowest value (17.6 +/- 8.8 fmol/mg prote in). Scatchard analyses of the ANF binding characteristics (K(d), B(ma x)) revealed both low (94 +/- 55 fmol/mg protein) and high (1161 +/- 6 9 fmol/mg protein) B(max) values. Receptors with higher K(d) values th an those observed in other cardiac regions (K(d) between 30 and 60 pM) were found in the vena cava and in the heart ventricle (K(d) between 113.2 and 229 pM).