Identification and characterization of atrial natriuretic factor receptors in the rat retina.
The characteristics of atrial natriuretic factor (ANF) receptors where studied in rat retinal particulate preparations. Specific 125I-ANF binding to retinal particulate preparations was greater than 90% of total binding and saturable at a density (Bmax) of 40 +/- 8 fmol/mg protein with an apparent dissociation constant (Kd) of 6.0 +/- 2.0 pM (n = 3). Apparent equilibrium conditions were established within 30 min. The Kd value of 125I-ANF binding calculated by kinetic analysis was 4.0 pM. The Bmax of 60 +/- 10 fmol/mg protein and the Kd of 5 +/- 2 pM, calculated by competition analysis, were in close agreement with the values obtained from Scatchard plots or kinetic analysis. The 125I-ANF binding to retinal particulate preparations was not inhibited by 1 microM concentration of somatostatin, vasopressin, vasoactive intestinal peptide, adrenocorticotropin, thyrotropin releasing hormone, or leu-enkephalin. The rank order of potency of the unlabelled atrial natriuretic peptides for competing with specific 125I-ANF (101-126) binding sites was rANF (92-126) greater than rANF (101-126) greater than rANF (99-126) greater than rANF (103-126) greater than Tyro-Atriopeptin I greater than hANF (105-126) greater than rANF (1-126). Similar results have been obtained in peripheral tissues and mammalian brain, indicating that central and peripheral ANF-binding sites have somewhat similar structural requirements. Affinity cross-linking of 125I-ANF to retinal particulate preparations resulted in the labelling of two sites of molecular weight 140 and 66 kDa, respectively. This demonstration of specific high-affinity ANF receptors suggests that the peptide may act as a neurotransmitter or neuromodulator in the retina.
Fernandez-Durango
R
R
Diabetes, Hypertension and Obesity Unit, Hospital Universitario San Carlos, Faculty of Medicine, Madrid, Spain.
Sanchez
D
D
Gutkowska
J
J
Carrier
F
F
Fernandez-Cruz
A
A
D000345:Affinity Labels; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000378:metabolism*; D001667:Binding, Competitive; D002474:Cell-Free System; D066298:In Vitro Techniques; D007700:Kinetics; D008970:Molecular Weight; D051381:Rats; D017461:Receptors, Atrial Natriuretic Factor; D011956:Receptors, Cell Surface / Q000032:analysis / Q000378:metabolism*; D012160:Retina / Q000378:metabolism*
D000345:Affinity Labels; D011956:Receptors, Cell Surface; C472610:atrial natriuretic peptide, rat; D009320:Atrial Natriuretic Factor; D017461:Receptors, Atrial Natriuretic Factor