Identification and quantification of human kidney atrial natriuretic peptide receptors.
The present study determined 125I-label atrial natriuretic peptide (ANP) binding sites in human kidney glomerular and papillary membranes. The membranes were prepared from non-malignant renal tissue obtained at nephrectomy of patients with renal carcinoma. To evaluate the proportion of ANP receptor classes ANP-R1 (ANPR-A, -B) versus ANP-R2 (ANPR-C), competitive binding studies were performed using [125I]-ANP in the presence of increasing concentrations of ANP or an internally ring-deleted analog, des(Gln116, Ser117, Gly118, Leu119, Gly120)ANP(102-121), called C-ANP, which binds selectively to ANPR-C receptors. Analysis of the competitive binding curve with ANP in glomerular membranes suggested the presence of one group of high-affinity receptors with dissociation constant Kd = 26 +/- 12 pmol/l and density Bmax = 101 +/- 47 nmol/kg protein. A decrease of 10-30% in Bmax with no change in Kd was obtained in the presence of excess (10(-6) mol/l) C-ANP, suggesting the existence of a small amount of a second class of receptors, the ANPR-C class. The densities of ANPR-A, -B versus ANPR-C receptors in human glomeruli, calculated from competitive inhibition experiments, were 75 +/- 42 and 22 +/- 16 nmol/kg protein (N = 8). Autoradiography of the sodium dodecyl sulfate polyacrylamide gel electrophoresis under reducing conditions showed two bands: a highly labeled 130kD band and a weakly labeled 66 kD band, both displaced by ANP. Only the 66-kD band was displaced by the C-ANP analog. Human papilla membrane, as shown by competition binding studies and SDS gel electrophoresis, presented only one class of receptors with Kd = 40 +/- 23 pmol/l (mean +/- SD, N = 3) and Bmax = 17 +/- 6.3 nmol/kg protein.(ABSTRACT TRUNCATED AT 250 WORDS)
Kahana
L
L
Endocrine Laboratory, Carmel Medical Center, Haifa, Israel.
Yechiely
H
H
Mecz
Y
Y
Lurie
A
A
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001345:Autoradiography; D001667:Binding, Competitive; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007457:Iodine Radioisotopes; D007678:Kidney Glomerulus / Q000737:chemistry* / Q000648:ultrastructure; D007679:Kidney Medulla / Q000737:chemistry* / Q000502:physiology / Q000648:ultrastructure; D008875:Middle Aged; D017461:Receptors, Atrial Natriuretic Factor / Q000032:analysis* / Q000145:classification / Q000502:physiology
D007457:Iodine Radioisotopes; D017461:Receptors, Atrial Natriuretic Factor